Emergency derepression: stringency allows RNA polymerase to override negative control by an active repressor.
The uspA promoter, driving production of the universal stress protein A in response to diverse stresses, is demonstrated to be under dual control. One regulatory pathway involves activation of the promoter by the alarmone guanosine 3',5'-bisphosphate, via the beta-subunit of RNA polymerase, whereas the other consists of negative control by the FadR repressor. In contrast to canonical dual control by activation and repression circuits, which depends on concomitant activation and derepression for induction to occur, the ppGpp-dependent activation of the uspA promoter overrides repression by an active FadR under conditions of severe cellular stress (starvation). The ability of RNA polymerase to overcome repression during stringency depends, in part, on the strength of the FadR operator. This emergency derepression is operative on other FadR-regulated genes induced by starvation and is argued to be an essential regulatory mechanism operating during severe stress.
Kvint
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K
Department of Cell and Molecular Biology - Microbiology, Göteborg University, Box 462, 405 30 Göteborg, Sweden.
Hosbond
C
C
Farewell
A
A
Nybroe
O
O
Nyström
T
T
D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D003066:Coenzyme A Ligases / Q000235:genetics / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D012321:DNA-Directed RNA Polymerases / Q000235:genetics* / Q000378:metabolism*; D015180:Electrophoresis, Gel, Two-Dimensional; D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D006159:Guanosine Tetraphosphate / Q000235:genetics / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D010957:Plasmids / Q000235:genetics; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D014161:Transduction, Genetic; D014169:Transformation, Bacterial; D001616:beta-Galactosidase
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C057119:FadR protein, Bacteria; D006360:Heat-Shock Proteins; D010940:Plant Proteins; D012097:Repressor Proteins; C101305:RpoB protein, Oryza sativa; C078564:universal stress protein A, Bacteria; D006159:Guanosine Tetraphosphate; D000242:Cyclic AMP; D012321:DNA-Directed RNA Polymerases; D001616:beta-Galactosidase; D003066:Coenzyme A Ligases; C085934:acyl-coenzyme A synthetase, E coli