Leucine-responsive regulatory protein controls the expression of both the pap and fan pili operons in Escherichia coli.
AUTOR(ES)
Braaten, B A
RESUMO
The methylation blocking factor gene (mbf) in Escherichia coli is required for specific methylation inhibition of two DNA GATC sites upstream of the papBA pilin promoter and transcriptional activation of pap. Complementation and mutational analysis using pap-lac and ilvIH-lac operon fusions indicates that the mbf gene is identical to a recently described global regulatory gene lrp (leucine-responsive regulatory protein) that acts as a positive regulator of some genes and a negative regulator of others in E. coli. DNA sequence analysis of an mbf::mTn10 insertion showed that the mbfDNA sequence was identical to lrp. Thus Lrp inhibits DNA methylation at specific GATC sites. We also show that Lrp positively regulates transcription of the fan operon, which encodes K99 pili of diarrheagenic E. coli. Purified Lrp was found to bind to DNA fragments encompassing the pap and fan promoters, which is consistent with previous results indicating that Lrp controls gene expression by binding to regulatory DNA sites. Exogenous leucine significantly reduced fan transcription and K99 pili expression, similar to results obtained with the ilvIH operon. However, pap gene expression was unresponsive to leucine, which distinguishes pap from other lrp-regulated genes whose expression is modulated by leucine.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=49059Documentos Relacionados
- The leucine-responsive regulatory protein, a global regulator of metabolism in Escherichia coli.
- Characterization of the regulon controlled by the leucine-responsive regulatory protein in Escherichia coli.
- The tdh and serA operons of Escherichia coli: mutational analysis of the regulatory elements of leucine-responsive genes.
- Lrp, a leucine-responsive protein, regulates branched-chain amino acid transport genes in Escherichia coli.
- Leucine-Responsive Regulatory Protein-Mediated Repression of clp (Encoding CS31A) Expression by l-Leucine and l-Alanine in Escherichia coli