title: [Escherichia coli K12 mutant with increased RNA content and messenger RNA stability].
abstract: A strain of Escherichia coli has been isolated from a E. coli HfrH after a treatment with nitrosoguanidine for a partial resistance to thymineless death. This strain shows, in addition, a global increase of the RNA content amounting to 50 per cent. The half-life of the unstable RNA as well as of the messenger RNA of the beta-galactosidase is increased to a considerable degree. The RNA polymerase of this strain is modified with respect to its resistance to rifampicin and its transcription efficiency in vitro of various DNA templates. Our working hypothesis is that the primary alteration of this strain lies at the RNA polymerase level with a consequent increase of the synthetic rate of the ribosomal RNA. The increase of the messenger RNA half-life may be an indirect consequence of this event via a saturation of the RNAase by the excess of ribosomal RNAs not associated to their proteins.
mesh_terms: D012321:DNA-Directed RNA Polymerases / Q000378:metabolism; D004926:Escherichia coli / Q000187:drug effects / Q000378:metabolism*; D006147:Guanine / Q000378:metabolism; D007700:Kinetics; D007930:Leucine / Q000378:metabolism; D009154:Mutation; D012329:RNA, Bacterial / Q000096:biosynthesis*; D012333:RNA, Messenger / Q000378:metabolism*; D012293:Rifampin / Q000494:pharmacology; D014498:Uracil / Q000378:metabolism
chemical_list: D012329:RNA, Bacterial; D012333:RNA, Messenger; D014498:Uracil; D006147:Guanine; D012321:DNA-Directed RNA Polymerases; D007930:Leucine; D012293:Rifampin
vernacular_title: Etude d'un mutant d'Escherichia coli K12 dont la teneur en RNA et la stabilité du RNA messager sont accrues