Phosphorylation and RsbX-dependent dephosphorylation of RsbR in the RsbR-RsbS complex of Bacillus subtilis.
In the pathway that controls sigmaB activity, the RsbR-RsbS complex plays an important role by trapping RsbT, a positive regulator of sigmaB of Bacillus subtilis. We have proposed that at the onset of stress, RsbR becomes phosphorylated, resulting in an enhanced activity of RsbT towards RsbS. RsbT is then free to interact with and activate RsbU, which in turn ultimately activates sigmaB. In this study with purified proteins, we used mutant RsbR proteins to analyze the role of its phosphorylatable threonine residues. The results show that the phosphorylation of either of the two RsbT-phosphorylatable threonine residues (T171 and T205) in RsbR enhanced the kinase activity of RsbT towards RsbS. However, it appeared that RsbT preferentially phosphorylates T171. We also present in vitro evidence that identifies RsbX as a potential phosphatase for RsbR T205.
Microbiology Unit, Department of Biochemistry, University of Oxford, South Parks Rd., Oxford OX1 3QU, United Kingdom.
Chien-Cheng
CC
Chen
Michael D
MD
Yudkin
Olivier
O
Delumeau
D001412:Bacillus subtilis / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D012808:Sigma Factor / Q000378:metabolism; D015398:Signal Transduction
D001426:Bacterial Proteins; D010750:Phosphoproteins; C119218:RsbR protein, Bacillus subtilis; C079011:SigB protein, Bacteria; D012808:Sigma Factor; C119219:RsbT protein, Bacillus subtilis; D017346:Protein Serine-Threonine Kinases; D010744:Phosphoric Monoester Hydrolases