The Escherichia coli FIS protein is not required for the activation of tyrT transcription on entry into exponential growth.
The Escherichia coli DNA bending protein factor for inversion stimulation (FIS), is neither necessary nor responsible for the stimulation of transcription from the wild type promoter for the tyrT operon (encoding a species of tyrosine tRNA) that occurs upon resumption of exponential growth. This conclusion is unexpected given that the regulatory element required for optimal transcription of tyrT contains three binding sites for FIS protein. In addition, it is in apparent conflict with reports from other laboratories which have described FIS-dependent activation of the stable RNA promoters rrnB P1 and thrU(tufB) in vivo. However, tyrT transcription is stimulated in a FIS-dependent manner both in vivo and in vitro when promoter function is impaired by mutation of the promoter itself or by the addition of the polymerase effector guanosine 5'-diphosphate 3'-diphosphate. These conditions, which expose a requirement for activation of stable RNA synthesis by FIS, suggest that FIS serves an adaptive role permitting high levels of stable RNA transcription on nutritional shift-up when RNA polymerase levels are depleted. In principle such a mechanism could confer a significant selective advantage thus accounting for the conservation of FIS binding sites in the regulatory regions of stable RNA promoters.
Lazarus
L R
LR
MRC Laboratory of Molecular Biology, Cambridge, UK.
Travers
A A
AA
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D002352:Carrier Proteins / Q000378:metabolism*; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029968:Escherichia coli Proteins; D035021:Factor For Inversion Stimulation Protein; D006159:Guanosine Tetraphosphate / Q000378:metabolism; D034982:Integration Host Factors; D008969:Molecular Sequence Data; D009154:Mutation; D011401:Promoter Regions, Genetic; D012329:RNA, Bacterial / Q000235:genetics; D012346:RNA, Transfer, Amino Acyl / Q000235:genetics*; D014158:Transcription, Genetic; D015533:Transcriptional Activation
D001426:Bacterial Proteins; D002352:Carrier Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D035021:Factor For Inversion Stimulation Protein; D034982:Integration Host Factors; D012329:RNA, Bacterial; D012346:RNA, Transfer, Amino Acyl; C440502:integration host factor, E coli; D006159:Guanosine Tetraphosphate