PMID:9852023
| Citation |
Gowrishankar, J and Pittard, AJ (1998) Superimposition of tyrR protein-mediated regulation on osmoresponsive transcription of Escherichia coli proU in vivo. J. Bacteriol. 180:6743-8 |
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| Abstract |
Osmotic regulation of proU expression in the enterobacteria is achieved, at least in part, by a repression mechanism involving the histone-like nucleoid protein H-NS. By the creation of binding sites for the TyrR regulator protein in the vicinity of the sigma70-controlled promoter of proU in Escherichia coli, we were able to demonstrate a superposed TyrR-mediated activation by L-phenylalanine (Phe), as well as repression by L-tyrosine, of proU expression in vivo. Based on the facts that pronounced activation in the presence of Phe was observed even at a low osmolarity and that the affinity of binding of TyrR to its cognate sites on DNA is not affected by Phe, we argue that H-NS-mediated repression of proU at a low osmolarity may not involve a classical silencing mechanism. Our data also suggest the involvement of recruited RNA polymerase in the mechanism of antirepression in E. coli. |
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| Keywords |
Amino Acid Transport Systems; Bacterial Proteins/genetics; Carrier Proteins/genetics; DNA-Binding Proteins/genetics; DNA-Binding Proteins/physiology; Escherichia coli/genetics; Escherichia coli/metabolism; Escherichia coli Proteins; Gene Expression Regulation, Bacterial; Osmolar Concentration; Phenylalanine/metabolism; Promoter Regions, Genetic; Repressor Proteins/genetics; Repressor Proteins/metabolism; Transcription Factors/genetics; Transcription Factors/metabolism; Transcription, Genetic; Transcriptional Activation |
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