[Gene yddG of Escherichia coli encoding the putative exporter of aromatic amino acids: constitutive transcription and dependence of the expression level on the cell growth rate].

Gene yddG of Escherichia coli encodes a protein of the inner membrane. Data obtained earlier demonstrated that under conditions of oversynthesis of aromatic amino acids, YddG promotes their export from E. coli cells. In this work, a method of primer extension was used to localize the P(yddG) promoter, which corresponds to E. coli promoters recognized by RNA polymerase in complex with sigma70 or sigma(S) subunits. By constructing a gene of the hybrid protein YddG'-LacZ at the intrinsic site of gene yddG location in the E. coli chromosome and analyzing the activity of beta-galactosidase in cells growing on laboratory media LB and M9, the constitutive type of yddG expression at a low level was demonstrated (the activity reached approximately 3 to 4% of the level of LacZ in E. coli wild-type cells under induction of the lac operon). The expression of yddG had a twofold increase under conditions of retarded cell growth upon the stress caused by the high NaCl content (0.6 M) or by the presence of phenylalanine excess quantities (> 1 mM) in the culture medium.

KEYWORDS: {{ getKeywords(articleDetailText.words) }}