title: In vivo functional characterization of the transmembrane histidine kinase KinC in Bacillus subtilis.
abstract: In response to starvation, Bacillus subtilis cells differentiate into different subsets, undergoing cannibalism, biofilm formation or sporulation. These processes require a multiple component phosphorelay, wherein the master regulator Spo0A is activated upon phosphorylation by one or a combination of five histidine kinases (KinA-KinE) via two intermediate phosphotransferases, Spo0F and Spo0B. In this study, we focused on KinC, which was originally identified as a sporulation kinase and was later shown to regulate cannibalism and biofilm formation. First, genetic experiments using both the domesticated and undomesticated (biofilm forming) strains revealed that KinC activity and the membrane localization are independent of both the lipid raft marker proteins FloTA and cytoplasmic potassium concentration, which were previously shown to be required for the kinase activity. Next, we demonstrated that KinC controls cannibalism and biofilm formation in a manner dependent on phosphorelay. For further detailed characterization of KinC, we established an IPTG-inducible expression system in the domesticated strain, in which biofilm formation is defective, for simplicity of study. Using this system, we found that the N-terminal transmembrane domain is dispensable but the PAS domain is needed for the kinase activity. An in vivo chemical cross-linking experiment demonstrated that the soluble and functional KinC (KinC(ΔTM1+2)) forms a tetramer. Based on these results, we propose a revised model in which KinC becomes active by forming a homotetramer via the N-terminal PAS domain, but its activity is independent of both the lipid raft and the potassium leakage, which was previously suggested to be induced by surfactin.
authors.affiliation: Department of Biology and Biochemistry, University of Houston, Houston, TX 77204-5001, USA.
authors.forename: Seram Nganbiton
authors.initials: SN
authors.lastname: Devi
authors.affiliation: Department of Biology and Biochemistry, University of Houston, Houston, TX 77204-5001, USA.
authors.forename: Monika
authors.initials: M
authors.lastname: Vishnoi
authors.affiliation: Department of Biology and Biochemistry, University of Houston, Houston, TX 77204-5001, USA.
authors.forename: Brittany
authors.initials: B
authors.lastname: Kiehler
authors.affiliation: Department of Biology and Biochemistry, University of Houston, Houston, TX 77204-5001, USA.
authors.forename: Lindsey
authors.initials: L
authors.lastname: Haggett
authors.affiliation: Department of Biology and Biochemistry, University of Houston, Houston, TX 77204-5001, USA.
authors.forename: Masaya
authors.initials: M
authors.lastname: Fujita
mesh_terms: D001412:Bacillus subtilis / Q000235:genetics* / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D018441:Biofilms; D002462:Cell Membrane / Q000378:metabolism; D004789:Enzyme Activation; D015964:Gene Expression Regulation, Bacterial; D000071677:Histidine Kinase; D042541:Intracellular Space; D010766:Phosphorylation; D011188:Potassium / Q000378:metabolism; D054730:Protein Interaction Domains and Motifs; D011494:Protein Kinases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D055503:Protein Multimerization
chemical_list: D001426:Bacterial Proteins; D011494:Protein Kinases; D000071677:Histidine Kinase; D011188:Potassium