Réponses antivirales chez le moustique Aedes

@article{,

title = {Expression of an active form of recombinant Ty1 reverse transcriptase in Escherichia coli: a fusion protein containing the C-terminal region of the Ty1 integrase linked to the reverse transcriptase-RNase H domain exhibits polymerase and RNase H activities},

author = { M. Wilhelm and M. Boutabout and F. X. Wilhelm},

year  = {2000},

date = {2000-01-01},

journal = {Biochem J},

volume = {348},

number = {Pt 2},

pages = {337-42},

abstract = {Replication of the Saccharomyces cerevisiae Ty1 retrotransposon requires a reverse transcriptase capable of synthesizing Ty1 DNA. The first description of an active form of a recombinant Ty1 enzyme with polymerase and RNase H activities is reported here. The Ty1 enzyme was expressed as a hexahistidine-tagged fusion protein in Escherichia coli to facilitate purification of the recombinant protein by metal-chelate chromatography. Catalytic activity of the recombinant protein was detected only when amino acid residues encoded by the integrase gene were added to the N-terminus of the reverse transcriptase-RNase H domain. This suggests that the integrase domain could play a role in proper folding of reverse transcriptase. Several biochemical properties of the Ty1 enzyme were analysed, including the effect of MgCl(2), NaCl, temperature and of the chain terminator dideoxy GTP on its polymerase activity. RNase H activity was examined by monitoring the cleavage of a RNA-DNA template-primer. Our results suggest that the distance between the RNase H and polymerase active sites corresponds to the length of a 14-nucleotide RNA-DNA heteroduplex. The recombinant protein produced in E. coli should be useful for further biochemical and structural analyses and for a better understanding of the role of integrase in the activation of reverse transcriptase.},

note = {0264-6021 

Journal Article},

keywords = {&, Acid, affinity, Alignment, Amino, Calf, cerevisiae/*enzymology/*genetics, Chromatography, Cloning, Codon, coli, Comparative, Data, DNA, DNA/metabolism, Escherichia, Frames, Fusion, Genetic, Gov't, H, Heteroduplexes/metabolism, HIV-1, Homology, Integrases/chemistry/metabolism, Kinetics, Molecular, Non-U.S., Nucleic, Open, Polymerase/chemistry/isolation, Proteins/chemistry/isolation, purification/*metabolism, purification/metabolism, Reading, Recombinant, Retroelements/*genetics, Reverse, Ribonuclease, RNA-Directed, RNA/metabolism, Saccharomyces, Sequence, Study, Support, Templates, Terminator, Thymus/isolation, Transcriptase/chemistry},

pubstate = {published},

tppubtype = {article}

}

@article{imler_lps-induced_2000,

title = {LPS-induced immune response in Drosophila},

author = {Jean-Luc Imler and Servane Tauszig and Emmanuelle Jouanguy and C Forestier and Jules A Hoffmann},

issn = {0968-0519},

year  = {2000},

date = {2000-01-01},

journal = {Journal of Endotoxin Research},

volume = {6},

number = {6},

pages = {459--462},

abstract = {The study of the regulation of the inducible synthesis of antimicrobial peptides in Drosophila melanogaster has established this insect as a powerful model in which to study innate immunity. In particular, the molecular characterization of the regulatory pathway controlling the antifungal peptide drosomycin has revealed the importance of Toll receptors in innate immunity. We report here that injection of LPS into flies induces an immune response, suggesting that LPS receptors are used in Drosophila to detect Gram-negative bacteria infection. We have identified in the recently sequenced genome of Drosophila eight genes coding for Toll-like receptors in addition to Toll, which may function as LPS receptors. However, overexpression of a selection of these genes in tissue-culture cells does not result in up-regulation of the antibacterial peptide genes. These results are discussed in light of the recent data from genetic screens aimed at identifying the genes controlling the antibacterial response in Drosophila.},

keywords = {Animals, Biological, Cell Line, Cell Surface, Defensins, Genes, Genetic, hoffmann, imler, Insect, Insect Proteins, Lipopolysaccharides, M3i, Membrane Glycoproteins, Models, Mutation, Promoter Regions, Receptors, Signal Transduction, Toll-Like Receptors},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Expression of an active form of recombinant Ty1 reverse transcriptase in Escherichia coli: a fusion protein containing the C-terminal region of the Ty1 integrase linked to the reverse transcriptase-RNase H domain exhibits polymerase and RNase H activities},

author = {M Wilhelm and M Boutabout and F X Wilhelm},

url = {http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=10816427},

isbn = {10816427},

year  = {2000},

date = {2000-01-01},

journal = {Biochem J},

volume = {348},

number = {Pt 2},

pages = {337-342},

abstract = {Replication of the Saccharomyces cerevisiae Ty1 retrotransposon requires a reverse transcriptase capable of synthesizing Ty1 DNA. The first description of an active form of a recombinant Ty1 enzyme with polymerase and RNase H activities is reported here. The Ty1 enzyme was expressed as a hexahistidine-tagged fusion protein in Escherichia coli to facilitate purification of the recombinant protein by metal-chelate chromatography. Catalytic activity of the recombinant protein was detected only when amino acid residues encoded by the integrase gene were added to the N-terminus of the reverse transcriptase-RNase H domain. This suggests that the integrase domain could play a role in proper folding of reverse transcriptase. Several biochemical properties of the Ty1 enzyme were analysed, including the effect of MgCl(2), NaCl, temperature and of the chain terminator dideoxy GTP on its polymerase activity. RNase H activity was examined by monitoring the cleavage of a RNA-DNA template-primer. Our results suggest that the distance between the RNase H and polymerase active sites corresponds to the length of a 14-nucleotide RNA-DNA heteroduplex. The recombinant protein produced in E. coli should be useful for further biochemical and structural analyses and for a better understanding of the role of integrase in the activation of reverse transcriptase.},

note = {0264-6021 

Journal Article},

keywords = {Affinity  Cloning, Amino Acid  Support, Amino Acid Sequence  Chromatography, Calf Thymus/isolation & purification/*metabolism  Saccharomyces cerevisiae/*enzymology/*genetics  Sequence Alignment  Sequence Homology, Genetic, Molecular  Codon, Non-U.S. Gov't  Templates, Unité ARN},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Dynamics of the HIV-1 reverse transcription complex during initiation of DNA synthesis},

author = {J M Lanchy and C Isel and G Keith and S F Le Grice and C Ehresmann and B Ehresmann and R Marquet},

url = {http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=10766870},

isbn = {10766870},

year  = {2000},

date = {2000-01-01},

journal = {J Biol Chem},

volume = {275},

number = {16},

pages = {12306-12312},

abstract = {Initiation of human immunodeficiency virus-1 (HIV-1) reverse transcription requires formation of a complex containing the viral RNA (vRNA), tRNA(3)(Lys) and reverse transcriptase (RT). The vRNA and the primer tRNA(3)(Lys) form several intermolecular interactions in addition to annealing of the primer 3' end to the primer binding site (PBS). These interactions are crucial for the efficiency and the specificity of the initiation of reverse transcription. However, as they are located upstream of the PBS, they must unwind as DNA synthesis proceeds. Here, the dynamics of the complex during initiation of reverse transcription was followed by enzymatic probing. Our data revealed reciprocal effects of the tertiary structure of the vRNA.tRNA(3)(Lys) complex and reverse transcriptase (RT) at a distance from the polymerization site. The structure of the initiation complex allowed RT to interact with the template strand up to 20 nucleotides upstream from the polymerization site. Conversely, nucleotide addition by RT modified the tertiary structure of the complex at 10-14 nucleotides from the catalytic site. The viral sequences became exposed at the surface of the complex as they dissociated from the tRNA following primer extension. However, the counterpart tRNA sequences became buried inside the complex. Surprisingly, they became exposed when mutations prevented the intermolecular interactions in the initial complex, indicating that the fate of the tRNA depended on the tertiary structure of the initial complex.},

note = {0021-9258 

Journal Article},

keywords = {*Anticodon  Base Sequence  *DNA Replication  *Hiv-1  Human  Molecular Sequence Data  Mutagenesis  Nucleic Acid Conformation  RNA, Genetic, Lys/genetics/metabolism  RNA, MARQUET, Non-U.S. Gov't  Templates, Transfer, Unité ARN, Viral/genetics/metabolism  RNA-Directed DNA Polymerase/*metabolism  Support},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {A potential RNA drug target in the hepatitis C virus internal ribosomal entry site},

author = {R Klinck and E Westhof and S Walker and M Afshar and A Collier and F Aboul-Ela},

url = {http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=11073218},

isbn = {11073218},

year  = {2000},

date = {2000-01-01},

journal = {RNA},

volume = {6},

number = {10},

pages = {1423-1431},

abstract = {Subdomain IlId from the hepatitis C virus (HCV) internal ribosome entry site (IRES) has been shown to be essential for cap-independent translation. We have conducted a structural study of a 27-nt fragment, identical in sequence to IlId, to explore the structural features of this subdomain. The proposed secondary structure of IlId is comprised of two 3 bp helical regions separated by an internal loop and closed at one end by a 6-nt terminal loop. NMR and molecular modeling were used interactively to formulate a validated model of the three-dimensional structure of IlId. We found that this fragment contains several noncanonical structural motifs and non-Watson-Crick base pairs, some of which are common to other RNAs. In particular, a motif characteristic of the rRNA alpha-sarcin/ricin loop was located in the internal loop. The terminal loop, 5'-UUGGGU, was found to fold to form a trinucleotide loop closed by a trans-wobble U.G base pair. The sixth nucleotide was bulged out to allow stacking of this U.G pair on the adjacent helical region. In vivo mutational analysis in the context of the full IRES confirmed the importance of each structural motif within IIId for IRES function. These findings may provide clues as to host cellular proteins that play a role in IRES-directed translation and, in particular, the mechanism through which host ribosomes are sequestered for viral function.},

note = {1355-8382 

Journal Article},

keywords = {Base Pairing  Base Sequence  Computational Biology  *Drug Design  Endoribonucleases/metabolism  Genetic Engineering  Hepacivirus/*genetics  Models, Biomolecular  *Nucleic Acid Conformation  RNA, Genetic, Messenger/chemistry/genetics/metabolism  RNA, Molecular  Molecular Sequence Data  Mutation  Nuclear Magnetic Resonance, Nucleic Acid/*genetics  Reproducibility of Results  Ribosomes/*metabolism  Ricin/metabolism  Structure-Activity Relationship  Substrate Specificity  Translation, Unité ARN, Viral/*chemistry/genetics/*metabolism  Regulatory Sequences},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {A three-dimensional perspective on exon binding by a group II self-splicing intron},

author = {M Costa and F Michel and E Westhof},

url = {http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=10990464},

isbn = {10990464},

year  = {2000},

date = {2000-01-01},

journal = {EMBO J},

volume = {19},

number = {18},

pages = {5007-5018},

abstract = {We have used chemical footprinting, kinetic dissection of reactions and comparative sequence analysis to show that in self-splicing introns belonging to subgroup IIB, the sites that bind the 5' and 3' exons are connected to one another by tertiary interactions. This unanticipated arrangement, which contrasts with the direct covalent linkage that prevails in the other major subdivision of group II (subgroup IIA), results in a unique three-dimensional architecture for the complex between the exons, their binding sites and intron domain V. A key feature of the modeled complex is the presence of several close contacts between domain V and one of the intron-exon pairings. These contacts, whose existence is supported by hydroxyl radical footprinting, provide a structural framework for the known role of domain V in catalysis and its recently demonstrated involvement in binding of the 5' exon.},

note = {0261-4189 

Journal Article},

keywords = {Base Sequence  Catalysis  *Exons  Hydroxyl Radical  *Introns  Kinetics  *Models, Catalytic/metabolism  Support, Genetic, Genetic  Molecular Sequence Data  Nucleic Acid Conformation  *RNA Splicing  RNA, Non-U.S. Gov't  Support, P.H.S.  Temperature  Transcription, U.S. Gov't, Unité ARN},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Probing RNA structure and RNA-ligand complexes with chemical probes},

author = {C Brunel and P Romby},

url = {http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=10889976},

isbn = {10889976},

year  = {2000},

date = {2000-01-01},

journal = {Methods Enzymol},

volume = {318},

pages = {3-21},

note = {0076-6879 

Journal Article 

Review 

Review, Tutorial},

keywords = {Crystallography, Genetic, ROMBY, Unité ARN, X-Ray  *Ligands  Nucleic Acid Conformation  Nucleotides/chemistry/metabolism  Proteins/chemistry  RNA/*chemistry/drug effects/*metabolism  Transcription},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {In vitro evidence for the interaction of tRNA(3)(Lys) with U3 during the first strand transfer of HIV-1 reverse transcription},

author = {F Brule and G Bec and G Keith and S F Le Grice and B P Roques and B Ehresmann and C Ehresmann and R Marquet},

url = {http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=10606665},

isbn = {10606665},

year  = {2000},

date = {2000-01-01},

journal = {Nucleic Acids Res},

volume = {28},

number = {2},

pages = {634-640},

abstract = {Over the course of its evolution, HIV-1 has taken maximum advantage of its tRNA(3)(Lys)primer by utilizing it in several steps of reverse transcription. Here, we have identified a conserved nonanucleotide sequence in the U3 region of HIV-1 RNA that is complementary to the anticodon stem of tRNA(3)(Lys). In order to test its possible role in the first strand transfer reaction, we applied an assay using a donor RNA corresponding to the 5'-part and an acceptor RNA spanning the 3'-part of HIV-1 RNA. In addition, we constructed two acceptor RNAs in which the nonanucleotide sequence complementary to tRNA(3)(Lys)was either substituted (S) or deleted (Delta). We used either natural tRNA(3)(Lys)or an 18 nt DNA as primer and measured the efficiency of (-) strand strong stop DNA transfer in the presence of wild-type, S or Delta acceptor RNA. Mutations in U3 did not decrease the transfer efficiency when reverse transcription was primed with the 18mer DNA. However, they significantly reduced the strand transfer efficiency in the tRNA(3)(Lys)-primed reactions. This reduction was also observed in the presence of nucleocapsid protein. These results suggest that tRNA(3)(Lys)increases (-) strand strong stop transfer by interacting with the U3 region of the genomic RNA. Sequence comparisons suggest that such long range interactions also exist in other lentiviruses.},

note = {1362-4962 

Journal Article},

keywords = {Base Sequence  HIV-1 Reverse Transcriptase/*metabolism  Nucleic Acid Conformation  Polymerase Chain Reaction  RNA, Genetic, Lys/*metabolism  RNA, MARQUET, Non-U.S. Gov't  *Transcription, Transfer, Unité ARN, Viral/chemistry/*metabolism  Support},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Role of post-transcriptional modifications of primer tRNALys,3 in the fidelity and efficacy of plus strand DNA transfer during HIV-1 reverse transcription},

author = { S. Auxilien and G. Keith and S. F. Le Grice and J. L. Darlix},

year  = {1999},

date = {1999-01-01},

journal = {J Biol Chem},

volume = {274},

number = {7},

pages = {4412-20},

abstract = {During HIV reverse transcription, (+) strand DNA synthesis is primed by an RNase H-resistant sequence, the polypurine tract, and continues as far as a 18-nt double-stranded RNA region corresponding to the 3' end of tRNALys,3 hybridized to the viral primer binding site (PBS). Before (+) strand DNA transfer, reverse transcriptase (RT) needs to unwind the double-stranded tRNA-PBS RNA in order to reverse-transcribe the 3' end of primer tRNALys,3. Since the detailed mechanism of (+) strand DNA transfer remains incompletely understood, we developed an in vitro system to closely examine this mechanism, composed of HIV 5' RNA, natural modified tRNALys,3, synthetic unmodified tRNALys,3 or oligonucleotides (RNA or DNA) complementary to the PBS, as well as the viral proteins RT and nucleocapsid protein (NCp7). Prior to (+) strand DNA transfer, RT stalls at the double-stranded tRNA-PBS RNA complex and is able to reverse-transcribe modified nucleosides of natural tRNALys,3. Modified nucleoside m1A-58 of natural tRNALys,3 is only partially effective as a stop signal, as RT can transcribe as far as the hyper-modified adenosine (ms2t6A-37) in the anticodon loop. m1A-58 is almost always transcribed into A, whereas other modified nucleosides are transcribed correctly, except for m7G-46, which is sometimes transcribed into T. In contrast, synthetic tRNALys,3, an RNA PBS primer, and a DNA PBS primer are completely reverse-transcribed. In the presence of an acceptor template, (+) strand DNA transfer is efficient only with templates containing natural tRNALys,3 or the RNA PBS primer. Sequence analysis of transfer products revealed frequent errors at the transfer site with synthetic tRNALys,3, not observed with natural tRNALys,3. Thus, modified nucleoside m1A-58, present in all retroviral tRNA primers, appears to be important for both efficacy and fidelity of (+) strand DNA transfer. We show that other factors such as the nature of the (-) PBS of the acceptor template and the RNase H activity of RT also influence the efficacy of (+) strand DNA transfer.},

note = {0021-9258 

Journal Article},

keywords = {*RNA, *Transcription, Acid, Base, Calf, Conformation, Data, DNA, Genetic, Gov't, H, HIV-1, HIV-1/*physiology, Lys/*metabolism, Molecular, Non-U.S., Nucleic, post-transcriptional, Processing, Reverse, Ribonuclease, RNA, Sequence, Support, Templates, Thymus/metabolism, Transcriptase/metabolism, Transfer, Viral/*metabolism, Viral/metabolism},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {The Candida albicans CUG-decoding ser-tRNA has an atypical anticodon stem-loop structure},

author = { V. M. Perreau and G. Keith and W. M. Holmes and A. Przykorska and M. A. Santos and M. F. Tuite},

year  = {1999},

date = {1999-01-01},

journal = {J Mol Biol},

volume = {293},

number = {5},

pages = {1039-53},

abstract = {In many Candida species, the leucine CUG codon is decoded by a tRNA with two unusual properties: it is a ser-tRNA and, uniquely, has guanosine at position 33 (G33). Using a combination of enzymatic (V1 RNase, RnI nuclease) and chemical (Pb(2+), imidazole) probing of the native Candida albicans ser-tRNACAG, we demonstrate that the overall tertiary structure of this tRNA resembles that of a ser-tRNA rather than a leu-tRNA, except within the anticodon arm where there is considerable disruption of the anticodon stem. Using non-modified in vitro transcripts of the C. albicans ser-tRNACAG carrying G, C, U or A at position 33, we demonstrate that it is specifically a G residue at this position that induces the atypical anticodon stem structure. Further quantitative evidence for an unusual structure in the anticodon arm of the G33-tRNA is provided by the observed change in kinetics of methylation of the G at position 37, by purified Escherichia coli m(1)G37 methyltransferase. We conclude that the anticodon arm distortion, induced by a guanosine base at position 33 in the anticodon loop of this novel tRNA, results in reduced decoding ability which has facilitated the evolution of this tRNA without extinction of the species encoding it.},

note = {0022-2836 

Journal Article},

keywords = {*Nucleic, Acid, albicans/*genetics, Anticodon/*chemistry/*genetics/metabolism, Base, Candida, cerevisiae/genetics, Code/genetics, Conformation, Evolution, Fungal/chemistry/genetics/metabolism, Genetic, Gov't, Imidazoles/metabolism, Lead/metabolism, Methylation, Methyltransferases/metabolism, Molecular, Mutation/genetics, Non-P.H.S., Non-U.S., Nucleosides/genetics/metabolism, P.H.S., Ribonucleases/metabolism, RNA, Saccharomyces, Sequence, Ser/*chemistry/*genetics/metabolism, Solutions, Support, Transfer, tRNA, U.S.},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Reverse transcription of the yeast Ty1 retrotransposon: the mode of first strand transfer is either intermolecular or intramolecular},

author = { M. Wilhelm and M. Boutabout and T. Heyman and F. X. Wilhelm},

year  = {1999},

date = {1999-01-01},

journal = {J Mol Biol},

volume = {288},

number = {4},

pages = {505-10},

abstract = {Replication of the yeast Ty1 retrotransposon occurs by a mechanism similar to that of retroviruses. According to the current model of retroviral reverse transcription, two strand transfers (the so-called minus-strand and plus-strand strong-stop DNA transfers) are required to produce full-length preintegrative DNA. Because two genomic RNA molecules are packaged inside the viral particles, the strand transfers can be either intra- or intermolecular. To study the mode of transfer of minus-strand strong-stop DNA during reverse transcription of the yeast Ty1 retrotransposon, we have analyzed the cDNA products that accumulate in the cytoplasmic virus-like particles of yeast cells harboring two marked Ty1 elements. Our results indicate that Ty1 minus-strand transfer occurs in a random manner with approximately similar frequencies of intra- and intermolecular transfer. It has been observed recently that intra- and intermolecular minus-strand transfer occur at similar frequencies during replication of a complex retrovirus such as HIV-1. These results together with the observation that genetic recombination occurs with a high frequency during minus-strand synthesis suggest that both packaged RNA molecules are needed for the synthesis of one minus-strand DNA.},

note = {0022-2836 

Journal Article},

keywords = {*Retroelements, *Transcription, Acid, Base, cerevisiae/*genetics, DNA, Genetic, Gov't, Non-U.S., Nucleic, Repetitive, Saccharomyces, Sequence, Sequences, Single-Stranded/genetics, Support},

pubstate = {published},

tppubtype = {article}

}

@article{lowenberger_mosquito-plasmodium_1999,

title = {Mosquito-Plasmodium interactions in response to immune activation of the vector},

author = {C A Lowenberger and S Kamal and J Chiles and S Paskewitz and Philippe Bulet and Jules A Hoffmann and B M Christensen},

doi = {10.1006/expr.1999.4350},

issn = {0014-4894},

year  = {1999},

date = {1999-01-01},

journal = {Exp. Parasitol.},

volume = {91},

number = {1},

pages = {59--69},

abstract = {During the development of Plasmodium sp. within the mosquito midgut, the parasite undergoes a series of developmental changes. The elongated ookinete migrates through the layers of the midgut where it forms the oocyst under the basal lamina. We demonstrate here that if Aedes aegypti or Anopheles gambiae, normally susceptible to Plasmodium gallinaceum and P. berghei, respectively, are immune activated by the injection of bacteria into the hemocoel, and subsequently are fed on an infectious bloodmeal, there is a significant reduction in the prevalence and mean intensity of infection of oocysts on the midgut. Only those mosquitoes immune activated prior to, or immediately after, parasite ingestion exhibit this reduction in parasite development. Mosquitoes immune activated 2-5 days after bloodfeeding show no differences in parasite burdens compared with naive controls. Northern analyses reveal that transcriptional activity for mosquito defensins is not detected in the whole bodies of Ae. aegypti from 4 h to 10 days after ingesting P. gallinaceum, suggesting that parasite ingestion, passage from the food bolus through the midgut, oocyst formation, and subsequent release of sporozoites into the hemolymph do not induce the production of defensin. However, reverse transcriptase-PCR of RNA isolated solely from the midguts of Ae. aegypti indicates that transcription of mosquito defensins occurs in the midguts of naive mosquitoes and those ingesting an infectious or noninfectious bloodmeal. Bacteria-challenged Ae. aegypti showed high levels of mature defensin in the hemolymph that correlate with a lower prevalence and mean intensity of infection with oocysts. Because few oocysts were found on the midgut of immune-activated mosquitoes, the data suggest that some factor, induced by bacterial challenge, kills the parasite at a preoocyst stage.},

keywords = {Aedes, Animals, Anopheles, Culicidae, Defensins, Digestive System, Escherichia coli, Female, Genetic, Hemolymph, hoffmann, Insect Vectors, M3i, messenger, Micrococcus luteus, Plasmodium, Plasmodium berghei, Plasmodium gallinaceum, Proteins, Reverse Transcriptase Polymerase Chain Reaction, RNA, Transcription},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Reverse transcription of the yeast Ty1 retrotransposon: the mode of first strand transfer is either intermolecular or intramolecular},

author = {M Wilhelm and M Boutabout and T Heyman and F X Wilhelm},

url = {http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=10329158},

isbn = {10329158},

year  = {1999},

date = {1999-01-01},

journal = {J Mol Biol},

volume = {288},

number = {4},

pages = {505-510},

abstract = {Replication of the yeast Ty1 retrotransposon occurs by a mechanism similar to that of retroviruses. According to the current model of retroviral reverse transcription, two strand transfers (the so-called minus-strand and plus-strand strong-stop DNA transfers) are required to produce full-length preintegrative DNA. Because two genomic RNA molecules are packaged inside the viral particles, the strand transfers can be either intra- or intermolecular. To study the mode of transfer of minus-strand strong-stop DNA during reverse transcription of the yeast Ty1 retrotransposon, we have analyzed the cDNA products that accumulate in the cytoplasmic virus-like particles of yeast cells harboring two marked Ty1 elements. Our results indicate that Ty1 minus-strand transfer occurs in a random manner with approximately similar frequencies of intra- and intermolecular transfer. It has been observed recently that intra- and intermolecular minus-strand transfer occur at similar frequencies during replication of a complex retrovirus such as HIV-1. These results together with the observation that genetic recombination occurs with a high frequency during minus-strand synthesis suggest that both packaged RNA molecules are needed for the synthesis of one minus-strand DNA.},

note = {0022-2836 

Journal Article},

keywords = {Base Sequence  DNA, Genetic, Non-U.S. Gov't  *Transcription, Nucleic Acid  *Retroelements  Saccharomyces cerevisiae/*genetics  Support, Single-Stranded/genetics  Repetitive Sequences, Unité ARN},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {All in the family: structural and evolutionary relationships among three modular proteins with diverse functions and variable assembly},

author = { M. Bergdoll and L. D. Eltis and A. D. Cameron and P. Dumas and J. T. Bolin},

year  = {1998},

date = {1998-01-01},

journal = {Protein Sci},

volume = {7},

number = {8},

pages = {1661-70},

abstract = {The crystal structures of three proteins of diverse function and low sequence similarity were analyzed to evaluate structural and evolutionary relationships. The proteins include a bacterial bleomycin resistance protein, a bacterial extradiol dioxygenase, and human glyoxalase I. Structural comparisons, as well as phylogenetic analyses, strongly indicate that the modern family of proteins represented by these structures arose through a rich evolutionary history that includes multiple gene duplication and fusion events. These events appear to be historically shared in some cases, but parallel and historically independent in others. A significant early event is proposed to be the establishment of metal-binding in an oligomeric ancestor prior to the first gene fusion. Variations in the spatial arrangements of homologous modules are observed that are consistent with the structural principles of three-dimensional domain swapping, but in the unusual context of the formation of larger monomers from smaller dimers or tetramers. The comparisons support a general mechanism for metalloprotein evolution that exploits the symmetry of a homooligomeric protein to originate a metal binding site and relies upon the relaxation of symmetry, as enabled by gene duplication, to establish and refine specific functions.},

note = {0961-8368 

Journal Article},

keywords = {*Acetyltransferases, *Evolution, Acid, Amino, Bacterial, Burkholderia/*chemistry, Crystallography, Data, Genetic, Gov't, Homology, Human, Lactoylglutathione, Lyase/*chemistry, Models, Molecular, Non-U.S., Oxygenases/chemistry, P.H.S., Phylogeny, Protein, Proteins/*chemistry, Secondary, Sequence, structure, Support, U.S., X-Ray},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Interactions between Ty1 retrotransposon RNA and the T and D regions of the tRNA(iMet) primer are required for initiation of reverse transcription in vivo},

author = { S. Friant and T. Heyman and A. S. Bystrom and M. Wilhelm and F. X. Wilhelm},

year  = {1998},

date = {1998-01-01},

journal = {Mol Cell Biol},

volume = {18},

number = {2},

pages = {799-806},

abstract = {Reverse transcription of the Saccharomyces cerevisiae Ty1 retrotransposon is primed by tRNA(iMet) base paired to the primer binding site (PBS) near the 5' end of Ty1 genomic RNA. The 10-nucleotide PBS is complementary to the last 10 nucleotides of the acceptor stem of tRNA(iMet). A structural probing study of the interactions between the Ty1 RNA template and the tRNA(iMet) primer showed that besides interactions between the PBS and the 3' end of tRNA(iMet), three short regions of Ty1 RNA, named boxes 0, 1, and 2.1, interact with the T and D stems and loops of tRNA(iMet). To determine if these sequences are important for the reverse transcription pathway of the Ty1 retrotransposon, mutant Ty1 elements and tRNA(iMet) were tested for the ability to support transposition. We show that the Ty1 boxes and the complementary sequences in the T and D stems and loops of tRNA(iMet) contain bases that are critical for Ty1 retrotransposition. Disruption of 1 or 2 bp between tRNA(iMet) and box 0, 1, or 2.1 dramatically decreases the level of transposition. Compensatory mutations which restore base pairing between the primer and the template restore transposition. Analysis of the reverse transcription intermediates generated inside Ty1 virus-like particles indicates that initiation of minus-strand strong-stop DNA synthesis is affected by mutations disrupting complementarity between Ty1 RNA and primer tRNA(iMet).},

note = {0270-7306 

Journal Article},

keywords = {*Retroelements, *Transcription, Acid, Base, Binding, cerevisiae, Conformation, Data, DNA, Fungal/*metabolism, Fungal/biosynthesis, Genetic, Gov't, Met/*metabolism, Molecular, Mutagenesis, Non-U.S., Nucleic, Primers, Replication, RNA, Saccharomyces, Sequence, Sites, Support, Transfer},

pubstate = {published},

tppubtype = {article}

}

@article{levashina_two_1998,

title = {Two distinct pathways can control expression of the gene encoding the Drosophila antimicrobial peptide metchnikowin},

author = {Elena A Levashina and S Ohresser and Bruno Lemaitre and Jean-Luc Imler},

doi = {10.1006/jmbi.1998.1705},

issn = {0022-2836},

year  = {1998},

date = {1998-01-01},

journal = {Journal of Molecular Biology},

volume = {278},

number = {3},

pages = {515--527},

abstract = {Metchnikowin is a recently discovered proline-rich peptide from Drosophila with antibacterial and antifungal properties. Like most other antimicrobial peptides from insects, its expression is immune-inducible. Here we present evidence that induction of metchnikowin gene expression can be mediated either by the TOLL pathway or by the imd gene product. We show that the gene remains inducible in Toll-deficient mutants, in which the antifungal response is blocked, as well as in imd mutants, which fail to mount an antibacterial response. However, in Toll-deficient;imd double mutants, metchnikowin gene expression can no longer be detected after immune challenge. Our results suggest that expression of this peptide with dual activity can be triggered by signals generated by either bacterial or fungal infection. Cloning of the metchnikowin gene revealed the presence in the 5' flanking region of several putative cis-regulatory motifs characterized in the promoters of insect immune genes: namely, Rel sites, GATA motifs, interferon consensus response elements and NF-IL6 response elements. Establishment of transgenic fly lines in which the GFP reporter gene was placed under the control of 1.5 kb of metchnikowin gene upstream sequences indicates that this fragment is able to confer full immune inducibility and tissue specificity of expression on the transgene.},

keywords = {Animals, Anti-Infective Agents, Antimicrobial Cationic Peptides, Base Sequence, Cloning, Gene Expression Regulation, Genes, Genetic, Genetically Modified, Glycopeptides, imler, Insect, Insect Proteins, Larva, M3i, Molecular, Mutation, Peptides, Promoter Regions, Recombinant Fusion Proteins, Reporter, Restriction Mapping, Transcription},

pubstate = {published},

tppubtype = {article}

}

@article{meister_antimicrobial_1997,

title = {Antimicrobial peptide defense in Drosophila},

author = {Marie Meister and Bruno Lemaitre and Jules A Hoffmann},

doi = {10.1002/bies.950191112},

issn = {0265-9247},

year  = {1997},

date = {1997-11-01},

journal = {Bioessays},

volume = {19},

number = {11},

pages = {1019--1026},

abstract = {Drosophila responds to a septic injury by the rapid synthesis of antimicrobial peptides. These molecules are predominantly produced by the fat body, a functional equivalent of mammalian liver, and are secreted into the hemolymph where their concentrations can reach up to 100 microM. Six distinct antibacterial peptides (plus isoforms) and one antifungal peptide have been characterized in Drosophila and their genes cloned. The induction of the gene encoding the antifungal peptide relies on the spätzle/Toll/cactus gene cassette, which is involved in the control of dorsoventral patterning in the embryo, and shows interesting structural and functional similarities with cytokine-induced activation of NF-kappa B in mammalian cells. An additional pathway, dependent on the as yet unidentified imd (for immune-deficiency) gene, is required for the full induction of the antibacterial peptide genes. Mutants deficient for the Toll and imd pathways exhibit a severely reduced survival to fungal and bacterial infections, respectively. Recent data on the molecular mechanisms underlying recognition of non-self are also discussed in this review.},

keywords = {Animals, Anti-Infective Agents, Gene Expression Regulation, Genetic, hoffmann, Insect Proteins, M3i, Models, Peptides, Promoter Regions, Signal Transduction},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Heterogeneous terminal structure of Ty1 and Ty3 reverse transcripts},

author = { M. Wilhelm and T. Heyman and S. Friant and F. X. Wilhelm},

year  = {1997},

date = {1997-01-01},

journal = {Nucleic Acids Res},

volume = {25},

number = {11},

pages = {2161-6},

abstract = {A specific terminal structure of preintegrative DNA is required for transposition of retroviruses and LTR-retrotransposons. We have used an anchored PCR technique to map the 3'ends of DNA intermediates synthesized inside yeast Ty1 and Ty3 retrotransposon virus-like particles. We find that, unlike retroviruses, Ty1 replicated DNA does not have two extra base pairs at its 3'ends. In contrast some Ty3 preintegrative DNA molecules have two extra nucleotides at the 3'end of upstream and downstream long terminal repeats. Moreover we find that some molecules of replicated Ty3 DNA have more than two extra nucleotides at the 3'end of the upstream LTR. This observation could be accounted for by imprecise RNAse H cutting of the PPT sequence. The site of Ty1 and Ty3 plus-strand strong-stop DNA termination was also examined. Our results confirm that the prominent Ty1 and Ty3 plus-strand strong-stop molecules harbor 12 tRNA templated bases but also show that some Ty1 and Ty3 plus-strand strong-stop DNA molecules harbor less tRNA templated bases. We propose that these less than full length plus-strand molecules could be active intermediates in Ty retrotransposon replication.},

note = {0305-1048 

Journal Article},

keywords = {*Nucleic, *Transcription, Acid, Calf, Chain, Conformation, DNA, Fungal/*chemistry/metabolism, Genetic, Gov't, H, Hybridization, Non-U.S., Nucleic, Plasmids/chemistry/genetics/metabolism, Polymerase, Reaction, Replication, Retroelements/*genetics, Ribonuclease, RNA, Support, Thymus/metabolism, Transfer/chemistry},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Heterogeneous terminal structure of Ty1 and Ty3 reverse transcripts},

author = {M Wilhelm and T Heyman and S Friant and F X Wilhelm},

url = {http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=9153316},

isbn = {9153316},

year  = {1997},

date = {1997-01-01},

journal = {Nucleic Acids Res},

volume = {25},

number = {11},

pages = {2161-2166},

abstract = {A specific terminal structure of preintegrative DNA is required for transposition of retroviruses and LTR-retrotransposons. We have used an anchored PCR technique to map the 3'ends of DNA intermediates synthesized inside yeast Ty1 and Ty3 retrotransposon virus-like particles. We find that, unlike retroviruses, Ty1 replicated DNA does not have two extra base pairs at its 3'ends. In contrast some Ty3 preintegrative DNA molecules have two extra nucleotides at the 3'end of upstream and downstream long terminal repeats. Moreover we find that some molecules of replicated Ty3 DNA have more than two extra nucleotides at the 3'end of the upstream LTR. This observation could be accounted for by imprecise RNAse H cutting of the PPT sequence. The site of Ty1 and Ty3 plus-strand strong-stop DNA termination was also examined. Our results confirm that the prominent Ty1 and Ty3 plus-strand strong-stop molecules harbor 12 tRNA templated bases but also show that some Ty1 and Ty3 plus-strand strong-stop DNA molecules harbor less tRNA templated bases. We propose that these less than full length plus-strand molecules could be active intermediates in Ty retrotransposon replication.},

note = {0305-1048 

Journal Article},

keywords = {Calf Thymus/metabolism  Support, DNA Replication  DNA, Fungal/*chemistry/metabolism  *Nucleic Acid Conformation  Nucleic Acid Hybridization  Plasmids/chemistry/genetics/metabolism  Polymerase Chain Reaction  RNA, Genetic, Non-U.S. Gov't  *Transcription, Transfer/chemistry  Retroelements/*genetics  Ribonuclease H, Unité ARN},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {RNA-RNA interaction is required for the formation of specific bicoid mRNA 3' UTR-STAUFEN ribonucleoprotein particles},

author = {D Ferrandon and I Koch and E Westhof and C Nusslein-Volhard},

url = {http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=9130719},

isbn = {9130719},

year  = {1997},

date = {1997-01-01},

journal = {EMBO J},

volume = {16},

number = {7},

pages = {1751-1758},

abstract = {The formation of the anterior pattern of the Drosophila embryo is dependent on the localization of the mRNA of the morphogen Bicoid (bcd) to the anterior pole of the egg cell. Staufen protein (STAU) is required in a late step of the localization to anchor the bcd mRNA in the anterior cytoplasm. We have shown previously that endogenous STAU associates specifically with injected bcd mRNA 3'-untranslated region (UTR), resulting in the formation of characteristic RNA-protein particles that are transported along microtubules of the mitotic spindles in a directed manner. The regions recognized by STAU in this in vivo assay are predicted to form three stem-loop structures involving large double-stranded stretches. Here, we show that the STAU interaction requires a double-stranded conformation of the stems within the RNA localization signal. In addition, base pairing between two single-stranded loops plays a major role in particle formation. This loop-loop interaction is intermolecular, not intramolecular; thus dimers or multimers of the RNA localization signal must be associated with STAU in these particles. The bcd mRNA 3' UTR can also dimerize in vitro in the absence of STAU. Thus, in addition to RNA-protein interactions, RNA-RNA interaction might be involved in the formation of ribonucleoprotein particles for transport and localization.},

note = {0261-4189 

Journal Article},

keywords = {Animals  Base Sequence  DNA Primers  Dimerization  Drosophila/embryology/genetics/*physiology  *Drosophila Proteins  Embryo, Genetic, Messenger/*biosynthesis/*chemistry/metabolism  RNA-Binding Proteins/*biosynthesis/*metabolism  Ribonucleoproteins/*metabolism  Trans-Activators/*biosynthesis  Translation, Nonmammalian/*physiology  Homeodomain Proteins/*biosynthesis  Insect Proteins/biosynthesis  Models, Structural  Molecular Sequence Data  *Nucleic Acid Conformation  RNA, Unité ARN},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Implications of RNA structure on the annealing of a potent antisense RNA directed against the human immunodeficiency virus type 1},

author = {S Eckardt and P Romby and G Sczakiel},

url = {http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=9335527},

isbn = {9335527},

year  = {1997},

date = {1997-01-01},

journal = {Biochemistry},

volume = {36},

number = {42},

pages = {12711-12721},

abstract = {Antisense RNA-mediated regulation in bacterial systems is related to the kinetics of RNA-RNA annealing in vitro. Here, we investigated the secondary structure of alphaY69, an effective HIV-directed antisense RNA in human cells. Purified RNA preparations contain a single conformer. The global structure was identified by a cleavage experiment under native conditions using a short complementary oligonucleotide and RNase H. Structural analyses indicate a three-domain structure of alphaY69 consisting of two stem-loop elements connected by a seven-nucleotide single-stranded hinge region. Kinetic data suggest that the formation of base pairs between a CGC triplet of alphaY69 and its target RNA is essential for fast annealing. The complementary sequence stretch of the target folds into a high-energy secondary structure. The relationship between modifications in structural elements of alphaY69 and the annealing kinetics suggested that rate-limiting steps of the annealing involve a single site of alphaY69 and do not involve its 5' or 3'-end. Further, the data indicate that both initial base-specific interactions and duplex formation are dependent on the CGC triplet of the central region of alphaY69. This mechanism represents a specific and efficient way of RNA-RNA annealing that is initiated by the interaction of unstructured RNA regions.},

note = {0006-2960 

Journal Article},

keywords = {Anti-HIV Agents/*chemistry/pharmacology  Base Sequence  Cells, Antisense/*chemistry/*pharmacology  RNA, Calf Thymus  Ribonuclease T1  Software  Support, Cultured  Electrophoresis, Genetic, Insertional  Mutagenesis, Non-U.S. Gov't  Thermodynamics  Transcription, Polyacrylamide Gel  HIV-1/*drug effects/genetics  Human  Kinetics  Molecular Sequence Data  Mutagenesis, ROMBY, Site-Directed  *Nucleic Acid Conformation  Oligodeoxyribonucleotides  Oligoribonucleotides/*chemistry/pharmacology  RNA, Unité ARN, Viral/*chemistry/drug effects  Ribonuclease H},

pubstate = {published},

tppubtype = {article}

}