title: Carbon source control of the phosphorylation state of the Bacillus subtilis carbon-flux regulator Crh in vivo.
abstract: Bacillus subtilis possesses carbon-flux regulating histidine protein (Crh), a paralog of the histidine protein (HPr) of the phosphotransferase system (PTS). Like HPr, Crh becomes (de)phosphorylated in vitro at residue Ser46 by the metabolite-controlled HPr kinase/phosphorylase HPrK/P. Depending on its phosphorylation state, Crh exerts regulatory functions in connection with carbohydrate metabolism. So far, knowledge on phosphorylation of Crh in vivo has been limited and derived from indirect evidence. Here, we studied the dynamics of Crh phosphorylation directly by non-denaturing gel electrophoresis followed by Western analysis. The results confirm that HPrK/P is the single kinase catalyzing phosphorylation of Crh in vivo. Accordingly, phosphorylation of Crh is triggered by the carbon source as observed previously for HPr, but with some differences. Phosphorylation of both proteins occurred during exponential growth and disappeared upon exhaustion of the carbon source. During exponential growth, ~80% of the Crh molecules were phosphorylated when cells utilized a preferred carbon source. The reverse distribution, i.e. around 20% of Crh molecules phosphorylated, was obtained upon utilization of less favorable substrates. This clear-cut classification of the substrates into two groups has not previously been observed for HPr(Ser)~P formation. The likely reason for this difference is the additional PTS-dependent phosphorylation of HPr at His15, which limits accumulation of HPr(Ser)~P.
authors.affiliation: Department of General Microbiology, Institute of Microbiology and Genetics, Georg-August-University, Göttingen, Germany.
authors.forename: Jens J
authors.initials: JJ
authors.lastname: Landmann
authors.forename: Susanne
authors.initials: S
authors.lastname: Werner
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Hillen
authors.forename: Jörg
authors.initials: J
authors.lastname: Stülke
authors.forename: Boris
authors.initials: B
authors.lastname: Görke
mesh_terms: D001412:Bacillus subtilis / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002244:Carbon / Q000378:metabolism; D057486:Carbon Cycle; D015964:Gene Expression Regulation, Bacterial; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation
chemical_list: D001426:Bacterial Proteins; C118042:Crh protein, Bacillus subtilis; D010750:Phosphoproteins; D002244:Carbon