Transcriptional analysis of the Caulobacter 4.5 S RNA ffs gene and the physiological basis of an ffs mutant with a Ts phenotype.
A temperature-sensitive (ts) mutation in the ffs gene, encoding 4.5 S RNA, gives rise to cell division and DNA replication defects in Caulobacter crescentus. The ffs gene is transcribed throughout the cell-cycle and is transcribed at similar rates in mutant (ffs36) and wild-type strains, but in the mutant the 4.5 S RNA is unstable leading to lower 4.5 S RNA levels. The ffs36 phenotype results from a single base change in one of the non-conserved stems of the mature RNA, and is completely rescued by a compensating mutation in the opposite strand, providing confirmation of the predicted secondary structure of the 4.5 S RNA. The Caulobacter ffs gene was shown to be functionally comparable to the Escherichia coli ffs gene by complementation. Comparison of the ffs36 strain to a ts secA strain of Caulobacter, also having cell-cycle and DNA replication phenotypes, showed that both exhibit a permanent induction of a heat shock response at the restrictive temperature. To explain the phenotype of both the secA and ffs36 strains, we propose that a cell-cycle checkpoint prevents further progression through the cell-cycle in response to increased intracellular levels of heat shock and misfolded proteins.
Winzeler
E
E
Department of Developmental Biology, Stanford University School of Medicine, CA 94305-5427, USA.
Wheeler
R
R
Shapiro
L
L
D000595:Amino Acid Sequence; D001483:Base Sequence; D016935:Caulobacter crescentus / Q000166:cytology / Q000235:genetics*; D002453:Cell Cycle / Q000502:physiology; D004926:Escherichia coli / Q000737:chemistry / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics; D005798:Genes, Bacterial / Q000235:genetics; D005816:Genetic Complementation Test; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D011401:Promoter Regions, Genetic / Q000235:genetics; D012329:RNA, Bacterial / Q000737:chemistry* / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017421:Sequence Analysis; D013696:Temperature; D014158:Transcription, Genetic / Q000235:genetics
D006360:Heat-Shock Proteins; D012329:RNA, Bacterial; D012333:RNA, Messenger