title: Termination troubles in Escherichia coli K12.
abstract: In this issue of Molecular Microbiology, Schaub and Hayes report that, compared with other enterobacteria, Escherichia coli K12 carries two mutations - one in the prfB gene encoding the release factor RF2, and the other in the rpsG gene encoding r-protein S7 - that together concur in compromising translation termination at the essential rpsG gene. As a consequence, the growth of E. coli K12 is very sensitive to a further mutation (rluD(-) ) that depresses RF2 activity, whereas the growth of its close relative, E. coli B, is not. We tentatively discuss how the K12-specific mutations in RF2 and S7 might have occurred and why inefficient translation termination at rpsG inhibits growth. The work of Schaub and Hayes illustrates the fact that, due probably to its long history in the laboratory, E. coli K12 has accumulated mutations that sometimes limit its value as a model for studying basic steps in prokaryotic gene expression.
authors.affiliation: CNRS UPR9073 associated with University Paris VII, Institut de Biologie Physico-chimique, 13 rue Pierre et Marie Curie 75005 Paris, France. marc.dreyfus@ibpc.fr
authors.forename: Marc
authors.initials: M
authors.lastname: Dreyfus
authors.forename: Valérie
authors.initials: V
authors.lastname: Heurgué-Hamard
mesh_terms: D048168:Escherichia coli K12 / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D020125:Mutation, Missense; D010443:Peptide Chain Termination, Translational; D010454:Peptide Termination Factors / Q000235:genetics / Q000378:metabolism; D012269:Ribosomal Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D029968:Escherichia coli Proteins; D010454:Peptide Termination Factors; D012269:Ribosomal Proteins; C557649:RpsG protein, E coli; C489006:prfB protein, E coli; C037442:ribosomal protein S7