Relative binding affinities of OmpR and OmpR-phosphate at the ompF and ompC regulatory sites

摘要: In Escherichia coli, porin gene expression is regulated, in part, by the two-component regulatory system consisting of two proteins EnvZ and OmpR. an integral inner membrane protein that phosphorylated cytoplasmic ATP on a histidine residue. modulates activity OmpR phosphorylation dephosphorylation. Phospho-OmpR (OmpR-P) binds to genes ompF ompC regulate their expression. The simple affinity model predicts as concentration OmpR-P increases, initially high-affinity binding sites are filled. Then lower occupied this ordered accounts for differential genes. We demonstrate acetyl phosphate phosphorylates at aspartate 55, same residue kinase EnvZ. Quantification level HPLC direct measurement affinities enabled us test model. Our results indicate dramatically increases its (greater than tenfold). also show F1 C1 not sufficiently different provide strong basis discrimination. consequences these observations considered.