title: In vivo domain-based functional analysis of the major sporulation sensor kinase, KinA, in Bacillus subtilis.
abstract: Sensor histidine kinases are widely used by bacteria to detect and respond to environmental signals. In Bacillus subtilis, KinA is a major kinase providing phosphate input to the phosphorelay that activates the sporulation pathway upon starvation via the phosphorylated Spo0A transcription factor. KinA contains three PAS domains in its amino-terminal sensor domain, which appear to be involved in the sensing of an unidentified sporulation signal(s) produced upon starvation. Prior biochemical studies have suggested that KinA forms a homodimer as a functional enzyme and that the most amino-terminal PAS domain (PAS-A) plays an important role in sensing the signal(s) to activate an ATP-dependent autophosphorylation reaction to a histidine residue. To analyze the structure and function of the kinase in vivo, we have used a strain in which the synthesis of KinA is under the control of an isopropyl-beta-d-thiogalactopyranoside (IPTG)-inducible promoter. In vivo functional studies in combination with domain-based deletion analysis show that the cytosolic KinA forms a homo-oligomer as an active form under both nutrient-rich and nutrient-depleted conditions via its amino- and carboxyl-terminal domains independently. Furthermore, we found that a mutant in which the PAS-A domain was deleted was still able to induce sporulation at a wild-type level irrespective of nutrient availability, suggesting that PAS-BC domains are sufficient to maintain the kinase activity. Based on these results, we propose that the primary role of the amino-terminal sensor domain is to form a stable complex as a functional kinase, but possibly not for the binding of an unidentified sporulation signal(s).
authors: Department of Biology and Biochemistry, University of Houston, Houston, TX 77204-5001, USA.
authors: Prahathees
authors: P
authors: Eswaramoorthy
authors: Tao
authors: T
authors: Guo
authors: Masaya
authors: M
authors: Fujita
mesh_terms: D001412:Bacillus subtilis / Q000502:physiology*; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D010766:Phosphorylation; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D011494:Protein Kinases / Q000235:genetics* / Q000378:metabolism*; D055503:Protein Multimerization; D017434:Protein Structure, Tertiary; D017384:Sequence Deletion; D015398:Signal Transduction
chemical_list: D001426:Bacterial Proteins; C075521:kinA protein, Bacillus subtilis; D011494:Protein Kinases