Repression of the aroP gene of Escherichia coli involves activation of a divergent promoter.
The repression of aroP expression which is mediated by the TyrR protein with phenylalanine, tyrosine, or tryptophan has been shown to be primarily a direct result of TyrR-mediated activation of a divergent promoter, P3, which directs the RNA polymerase away from promoter P1. Evidence which has been presented to support this conclusion is as follows. Repression of P1 does not occur either in vitro or in vivo if wild-type TyrR protein is substituted by the activation-negative mutant RQ10 (with an R-to-Q change at position 10). Repression of P1 is greatly diminished if the P3 promoter is inactivated or if a 5-bp insertion is made between the P3 promoter and the binding sites for TyrR. Repression is also abolished if the promoter strength of P1 is increased or a putative UP element associated with P3 is altered. Repression of the second promoter, P2, still occurs if the wild-type TyrR protein is substituted with RQ10 or EQ274. The tryptophan-mediated repression of aroP does not involve the TrpR protein.
Wang
P
P
Department of Microbiology, University of Melbourne, Parkville, Victoria, Australia.
Yang
J
J
Lawley
B
B
Pittard
A J
AJ
D026905:Amino Acid Transport Systems; D001426:Bacterial Proteins / Q000235:genetics*; D002352:Carrier Proteins / Q000235:genetics*; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D016254:Mutagenesis, Insertional; D009154:Mutation; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000235:genetics*; D014364:Tryptophan
D026905:Amino Acid Transport Systems; C063201:AroP protein, E coli; D001426:Bacterial Proteins; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D012097:Repressor Proteins; C069256:TyrR protein, E coli; D014364:Tryptophan