New members of the Escherichia coli sigmaE regulon identified by a two-plasmid system

Abstract

A previously established method, based on a two-plasmid system, was used to identify promoters recognized by RNA polymerase containing the extracytoplasmic stress response sigma factor sigmaE in Escherichia coli. In addition to previously identified rpoE-dependent promoters, 11 new promoters potentially directing the expression of 15 genes were identified that were active only after over-expression of rpoE. The promoters were confirmed and transcriptional start points of the promoters were determined by primer extension analysis and S1-nuclease mapping. All the promoters contained sequences similar to the consensus sequence of rpoE-dependent promoters. The new rpoE-dependent promoters governed expression of genes encoding proteins involved in primary metabolism (fusA, tufA, recR), phospholipid and lipopolysaccharide biosynthesis (psd, lpxP), signal transduction (sixA), proposed inner or outer membrane proteins (bacA, sbmA, smpA, yeaY), and proteins with unknown function (ybaB, yaiW, yiiS, yiiT, yfeY).