Publications
1997
Moine H, Nurse K, Ehresmann B, Ehresmann C, Ofengand J
In: Biochemistry, vol. 36, no. 44, pp. 13700-13709, 1997, ISBN: 9354641, (0006-2960 Journal Article).
Abstract | Links | BibTeX | Tags: 16S/chemical synthesis/*chemistry/genetics Ribosomes/chemistry/genetics Structure-Activity Relationship Support, Bacterial/*chemistry/genetics RNA, Base Sequence Cytosine Nucleotides/genetics Deoxyuridine Escherichia coli/genetics Guanine Nucleotides/genetics Molecular Sequence Data *Mutagenesis, Non-U.S. Gov't, Ribosomal, Site-Directed *Nucleic Acid Conformation RNA, Unité ARN
@article{,
title = {Conformational analysis of Escherichia coli 30S ribosomes containing the single-base mutations G530U, U1498G, G1401C, and C1501G and the double-base mutation G1401C/C1501G},
author = {H Moine and K Nurse and B Ehresmann and C Ehresmann and J Ofengand},
url = {http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=9354641},
isbn = {9354641},
year = {1997},
date = {1997-01-01},
journal = {Biochemistry},
volume = {36},
number = {44},
pages = {13700-13709},
abstract = {Biochemical and genetic studies have pointed out the importance of several sites in 16S ribosomal RNA of Escherichia coli in the decoding process. These sites consist of the core of the decoding center (1400/1500 region) and two other segments (530 and 1050/1200 regions). To detect a possible structural link between these functionally related regions, we analyzed their sensitivity to conformational changes induced by mutations which are located in each of these regions and are known to affect the decoding process. The conformations of five segments of 16S rRNA (1-106, 406-569, 780-978, 997-1247, and 1334-1519) were analyzed by chemical probing of 30S ribosomes containing the following mutations: G530U, U1498G, G1401C, C1501G, and G1401C/C1501G. Ribosomes reconstituted with natural wild-type 16S RNA showed only minor conformational differences with respect to ribosomes isolated from cells. When 16S RNA made in vitro replaced natural 16S RNA, a slightly looser conformation of the central core region was found. Mutant ribosomes made by reconstitution with mutant 16S RNA made in vitro showed conformational effects which were in all cases localized to the region of secondary structure surrounding the site of mutation. Although the core of the decoding center (1400/1500 region) and the two other sites (530 and 1050/1200 regions) participating in the decoding function have been functionally linked, our data indicate that they are structurally independent. They also provide evidence for an unusual structure of the 1400/1500 decoding center, possibly involving noncanonical interactions. Furthermore, the absence of any conformational effect induced by the G530U mutation except at the site of mutation itself points to its direct, as opposed to indirect, involvement in the decoding function of the ribosome.},
note = {0006-2960
Journal Article},
keywords = {16S/chemical synthesis/*chemistry/genetics Ribosomes/chemistry/genetics Structure-Activity Relationship Support, Bacterial/*chemistry/genetics RNA, Base Sequence Cytosine Nucleotides/genetics Deoxyuridine Escherichia coli/genetics Guanine Nucleotides/genetics Molecular Sequence Data *Mutagenesis, Non-U.S. Gov't, Ribosomal, Site-Directed *Nucleic Acid Conformation RNA, Unité ARN},
pubstate = {published},
tppubtype = {article}
}
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 Journal Article
In: J Mol Biol, vol. 253, no. 2, pp. 277-290, 1995, ISBN: 7563089, (0022-2836 Journal Article).
Abstract | Links | BibTeX | Tags: 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}
}