Global query on bacterial sirtuin CobB interactants reveals crosstalk with PRPP synthase Prs

Abstract

AbstractProtein lysine acetylation regulates a wide range of cellular functions. It is controlled by a family of NAD-dependent protein deacetylases called sirtuins. In eukaryotes, sirtuins activity is coupled to spatiotemporally-controlled NAD+ level, whereas the mechanism of their regulation in bacteria is less clear. E. coli possesses a single sirtuin – CobB. However, it is unclear how CobB activity is coupled to NAD+ metabolism. In this work we show that this coordination is achieved in E. coli cells through a CobB interaction with PRPP synthase Prs, an enzyme necessary for NAD+ synthesis. Employing global analysis of protein-protein interactions formed by CobB, we demonstrate that it forms a stable complex with Prs. This assembly stimulates CobB deacetylase activity and partially protects it from inhibition by nicotinamide. We provide evidence that Prs acetylation is not necessary for CobB binding but affects the global acetylome in vivo. Our results show that CobB ameliorates Prs activity under conditions of Prs cofactors deficiency. Therefore, we propose that CobB-Prs crosstalk orchestrates the NAD+ metabolism and protein acetylation in response to environmental cues.