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M3i
Modèles Insectes d’Immunité Innée
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1995
Brunel C, Romby P, Sacerdot C, de Smit M, Graffe M, Dondon J, van Duin J, Ehresmann B, Ehresmann C, Springer M
Stabilised secondary structure at a ribosomal binding site enhances translational repression in E. coli Article de journal
Dans: J Mol Biol, vol. 253, no. 2, p. 277-290, 1995, ISBN: 7563089, (0022-2836 Journal Article).
Résumé | Liens | BibTeX | Étiquettes: Bacterial *Gene Expression Regulation, Base Composition Base Sequence Binding Sites Comparative Study Enzyme Repression Escherichia coli/genetics/*metabolism Gene Expression Regulation, Enzymologic Homeostasis Kinetics Mathematics Models, Genetic *Translation, Genetic beta-Galactosidase/biosynthesis, Messenger/biosynthesis/*chemistry/*metabolism Recombinant Proteins/biosynthesis Ribosomes/*metabolism Support, Non-U.S. Gov't Temperature Threonine-tRNA Ligase/*biosynthesis Transcription, ROMBY, Site-Directed *Nucleic Acid Conformation RNA, Theoretical Molecular Sequence Data Mutagenesis, Unité ARN
@article{,
title = {Stabilised secondary structure at a ribosomal binding site enhances translational repression in E. coli},
author = {C Brunel and P Romby and C Sacerdot and M de Smit and M Graffe and J Dondon and J van Duin and B Ehresmann and C Ehresmann and M Springer},
url = {http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=7563089},
isbn = {7563089},
year = {1995},
date = {1995-01-01},
journal = {J Mol Biol},
volume = {253},
number = {2},
pages = {277-290},
abstract = {The expression of the gene encoding Escherichia coli threonyl-tRNA synthetase is negatively autoregulated at the translational level. The negative feedback is due to the binding of the synthetase to an operator site on its own mRNA located upstream of the initiation codon. The present work describes the characterisation of operator mutants that have the rare property of enhancing repression. These mutations cause (1) a low basal level of expression, (2) a temperature-dependent expression, and (3) an increased capacity of the synthetase to repress its own expression at low temperature. Surprisingly, this enhancement of repression is not explained by an increase of affinity of the mutant operators for the enzyme but by the formation, at low temperature, of a few supplementary base-pairs between the ribosomal binding site and a normally single-stranded domain of the operator. Although this additional base-pairing only slightly inhibits ribosome binding in the absence of repressor, simple thermodynamic considerations indicate that this is sufficient to increase repression. This increase is explained by the competition between the ribosome and repressor for overlapping regions of the mRNA. When the ribosomal binding site is base-paired, the ribosome cannot bind while the repressor can, giving the repressor the advantage in the competition. Thus, the existence of an open versus base-paired equilibrium in a ribosomal binding site of a translational operator amplifies the magnitude of control. This molecular amplification device might be an essential component of translational control considering the low free repressor/ribosome ratio of the low affinity of translational repressors for their target operators.},
note = {0022-2836
Journal Article},
keywords = {Bacterial *Gene Expression Regulation, Base Composition Base Sequence Binding Sites Comparative Study Enzyme Repression Escherichia coli/genetics/*metabolism Gene Expression Regulation, Enzymologic Homeostasis Kinetics Mathematics Models, Genetic *Translation, Genetic beta-Galactosidase/biosynthesis, Messenger/biosynthesis/*chemistry/*metabolism Recombinant Proteins/biosynthesis Ribosomes/*metabolism Support, Non-U.S. Gov't Temperature Threonine-tRNA Ligase/*biosynthesis Transcription, ROMBY, Site-Directed *Nucleic Acid Conformation RNA, Theoretical Molecular Sequence Data Mutagenesis, Unité ARN},
pubstate = {published},
tppubtype = {article}
}
The expression of the gene encoding Escherichia coli threonyl-tRNA synthetase is negatively autoregulated at the translational level. The negative feedback is due to the binding of the synthetase to an operator site on its own mRNA located upstream of the initiation codon. The present work describes the characterisation of operator mutants that have the rare property of enhancing repression. These mutations cause (1) a low basal level of expression, (2) a temperature-dependent expression, and (3) an increased capacity of the synthetase to repress its own expression at low temperature. Surprisingly, this enhancement of repression is not explained by an increase of affinity of the mutant operators for the enzyme but by the formation, at low temperature, of a few supplementary base-pairs between the ribosomal binding site and a normally single-stranded domain of the operator. Although this additional base-pairing only slightly inhibits ribosome binding in the absence of repressor, simple thermodynamic considerations indicate that this is sufficient to increase repression. This increase is explained by the competition between the ribosome and repressor for overlapping regions of the mRNA. When the ribosomal binding site is base-paired, the ribosome cannot bind while the repressor can, giving the repressor the advantage in the competition. Thus, the existence of an open versus base-paired equilibrium in a ribosomal binding site of a translational operator amplifies the magnitude of control. This molecular amplification device might be an essential component of translational control considering the low free repressor/ribosome ratio of the low affinity of translational repressors for their target operators.
1994
Benard L, Philippe C, Dondon L, Grunberg-Manago M, Ehresmann B, Ehresmann C, Portier C
Mutational analysis of the pseudoknot structure of the S15 translational operator from Escherichia coli Article de journal
Dans: Mol Microbiol, vol. 14, no. 1, p. 31-40, 1994, ISBN: 7830558, (0950-382x Journal Article).
Résumé | Liens | BibTeX | Étiquettes: Bacterial Molecular Sequence Data *Nucleic Acid Conformation Plasmids Protein Binding RNA, Bacteriophage lambda/genetics Base Sequence Binding Sites Codon DNA Mutational Analysis Escherichia coli/*genetics/metabolism *Gene Expression Regulation, Genetic beta-Galactosidase/biosynthesis, Genetic Translation, Messenger/*chemistry/*metabolism Recombinant Fusion Proteins/biosynthesis Restriction Mapping Ribosomal Proteins/biosynthesis/*genetics/metabolism Support, Non-U.S. Gov't Transcription, Unité ARN
@article{,
title = {Mutational analysis of the pseudoknot structure of the S15 translational operator from Escherichia coli},
author = {L Benard and C Philippe and L Dondon and M Grunberg-Manago and B Ehresmann and C Ehresmann and C Portier},
url = {http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=7830558},
isbn = {7830558},
year = {1994},
date = {1994-01-01},
journal = {Mol Microbiol},
volume = {14},
number = {1},
pages = {31-40},
abstract = {Expression of rpsO, the gene encoding the small ribosomal protein S15, is autoregulated at the translational level by S15, which binds to its mRNA in a region overlapping the ribosome-binding site. By measuring the effect of mutations on the expression of a translational rpsO-lacZ fusion and the S15 binding affinity for the translational operator, the formation of a pseudoknot in the operator site in vivo is fully demonstrated and appears to be a prerequisite for S15 binding. The mutational analysis suggests also that specific determinants for S15 binding are located in very limited regions of the structure formed by the pseudoknot. It is deduced that a specific pseudoknot conformation is a key element for autoregulation.},
note = {0950-382x
Journal Article},
keywords = {Bacterial Molecular Sequence Data *Nucleic Acid Conformation Plasmids Protein Binding RNA, Bacteriophage lambda/genetics Base Sequence Binding Sites Codon DNA Mutational Analysis Escherichia coli/*genetics/metabolism *Gene Expression Regulation, Genetic beta-Galactosidase/biosynthesis, Genetic Translation, Messenger/*chemistry/*metabolism Recombinant Fusion Proteins/biosynthesis Restriction Mapping Ribosomal Proteins/biosynthesis/*genetics/metabolism Support, Non-U.S. Gov't Transcription, Unité ARN},
pubstate = {published},
tppubtype = {article}
}
Expression of rpsO, the gene encoding the small ribosomal protein S15, is autoregulated at the translational level by S15, which binds to its mRNA in a region overlapping the ribosome-binding site. By measuring the effect of mutations on the expression of a translational rpsO-lacZ fusion and the S15 binding affinity for the translational operator, the formation of a pseudoknot in the operator site in vivo is fully demonstrated and appears to be a prerequisite for S15 binding. The mutational analysis suggests also that specific determinants for S15 binding are located in very limited regions of the structure formed by the pseudoknot. It is deduced that a specific pseudoknot conformation is a key element for autoregulation.