title: Role of the PAS sensor domains in the Bacillus subtilis sporulation kinase KinA.
abstract: Histidine kinases are sophisticated molecular sensors that are used by bacteria to detect and respond to a multitude of environmental signals. KinA is the major histidine kinase required for initiation of sporulation upon nutrient deprivation in Bacillus subtilis. KinA has a large N-terminal region (residues 1 to 382) that is uniquely composed of three tandem Per-ARNT-Sim (PAS) domains that have been proposed to constitute a sensor module. To further enhance our understanding of this "sensor" region, we defined the boundaries that give rise to the minimal autonomously folded PAS domains and analyzed their homo- and heteroassociation properties using analytical ultracentrifugation, nuclear magnetic resonance (NMR) spectroscopy, and multiangle laser light scattering. We show that PAS(A) self-associates very weakly, while PAS(C) is primarily a monomer. In contrast, PAS(B) forms a stable dimer (K(d) [dissociation constant] of <10 nM), and it appears to be the main N-terminal determinant of KinA dimerization. Analysis of KinA mutants deficient for one or more PAS domains revealed a critical role for PAS(B), but not PAS(A), in autophosphorylation of KinA. Our findings suggest that dimerization of PAS(B) is important for keeping the catalytic domain of KinA in a functional conformation. We use this information to propose a model for the structure of the N-terminal sensor module of KinA.
authors.affiliation: Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland, Australia.
authors.forename: Brit
authors.initials: B
authors.lastname: Winnen
authors.forename: Eric
authors.initials: E
authors.lastname: Anderson
authors.forename: James L
authors.initials: JL
authors.lastname: Cole
authors.forename: Glenn F
authors.initials: GF
authors.lastname: King
authors.forename: Susan L
authors.initials: SL
authors.lastname: Rowland
mesh_terms: D001412:Bacillus subtilis / Q000201:enzymology* / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D009682:Magnetic Resonance Spectroscopy; D011494:Protein Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D055503:Protein Multimerization / Q000235:genetics / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000235:genetics / Q000502:physiology; D014461:Ultracentrifugation
chemical_list: D001426:Bacterial Proteins; C075521:kinA protein, Bacillus subtilis; D011494:Protein Kinases