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Spo0B of Bacillus anthracis – a protein with pleiotropic functions
Author(s) -
Mattoo Abid R.,
Saif Zaman Mohd,
Dubey Gyanendra P.,
Arora Amit,
Narayan Azeet,
Jailkhani Noor,
Rathore Kusum,
Maiti Souvik,
Singh Yogendra
Publication year - 2008
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/j.1742-4658.2007.06240.x
Subject(s) - autophosphorylation , biochemistry , bacillus anthracis , nucleoside diphosphate kinase , isothermal titration calorimetry , allosteric regulation , dissociation constant , biology , atpase , enzyme , nucleotide , kinase , nucleoside triphosphate , adenosine triphosphate , chemistry , protein kinase a , genetics , receptor , bacteria , gene
Spo0B is an important component of the phosphorelay signal transduction pathway, the pathway involved in the initiation of sporulation in Bacillus subtilis . Bioinformatic, phylogenetic and biochemical studies showed that Spo0B of Bacillus anthracis has evolved from citrate/malate kinases. During the course of evolution, Spo0B has retained the characteristic histidine kinase boxes H, N, F, G 1 and G 2 , and has acquired nucleotide‐binding domains, Walker A and Walker B, of ATPases. Owing to the presence of these domains, autophosphorylation and ATPase activity was observed in Spo0B of B. anthracis . Mutational studies showed that among the six histidine residues, His13 of the H‐box is involved in the autophosphorylation activity of Spo0B, whereas Lys33 of the Walker A domain is associated with the ATPase activity of the protein. Thermodynamic and binding studies of the binding of Mg‐ATP to Spo0B using isothermal titration calorimetry (ITC) suggested that the binding is driven by favorable entropy changes and that the reaction is exothermic, with an apparent dissociation constant ( K d ) equal to 0.02 m m . The value of the dissociation constant ( K d = 0.05 m m ) determined by the intrinsic fluorescence of trytophan of Spo0B was similar to that obtained by ITC studies. The purified Spo0B of B. anthracis also showed nucleoside diphosphate kinase‐like activity of phosphate transfer from nucleoside triphosphate to nucleoside diphosphate. This is the first evidence for Spo0B of B. anthracis as an enzyme with histidine kinase and ATPase activities, which may have important roles to play in sporulation and pathogenesis.