Superimposition of TyrR Protein-Mediated Regulation on Osmoresponsive Transcription of Escherichia coli proU In Vivo
AUTOR(ES)
Gowrishankar, J.
FONTE
American Society for Microbiology
RESUMO
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 ς70-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.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=107782Documentos Relacionados
- Molecular analysis of the TyrR protein-mediated activation of mtr gene expression in Escherichia coli K-12.
- Evidence for involvement of proteins HU and RpoS in transcription of the osmoresponsive proU operon in Escherichia coli.
- Mutations in the tyrR gene of Escherichia coli which affect TyrR-mediated activation but not TyrR-mediated repression.
- The TyrR protein of Escherichia coli is a class I transcription activator.
- Regulation of aroL expression by TyrR protein and Trp repressor in Escherichia coli K-12.
