Involvement of protein acetylation in glucose-induced transcription of a stress-responsive promoter

In eukaryotes, lysine acetylation is a well-established post-translational modification that has been implicated in virtually all aspects of eukaryotic physiology. Although homologues of the enzymes that catalyse protein acetylation are widely conserved and distributed among bacterial species, not much is known about the impact of protein acetylation on bacterial physiology. Here, we present evidence that the Gcn5-like acetyltransferase YfiQ and the sirtuin deacetylase CobB play crucial roles in the transcription regulation of the periplasmic stress-responsive promoter cpxP when cells of Escherichia coli grow in the presence of glucose, an environment that induces protein acetylation. Under this growth condition, several acetylation sites were detected on three of the RNA polymerase subunits: beta, beta' and alpha. We focused on acetylations of the carboxy-terminal domain (CTD) of alpha because of its relative small size and its limited acetylation. We determined that K298 of alpha is acetylated in a glucose and YfiQ-dependent manner and that K298 is specifically required for glucose-induced cpxP transcription. Because the alpha CTD aids in promoter recognition by RNA polymerase, we propose its acetylation may influence bacterial physiology through effects on gene expression.