Open AccessFunctional characterization of WalRK: A two‐component signal transduction system from Bacillus anthracis
Author(s) -
Dhiman Alisha,
Bhatnagar Sonika,
Kulshreshtha Parul,
Bhatnagar Rakesh
Publication year - 2014
Publication title -
febs open bio
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.718
H-Index - 31
ISSN - 2211-5463
DOI - 10.1016/j.fob.2013.12.005
Subject(s) - regulon , bacillus anthracis , response regulator , histidine kinase , biology , two component regulatory system , in silico , phosphatase , autophosphorylation , signal transduction , biochemistry , kinase , anthrax toxin , microbiology and biotechnology , histidine , phosphorylation , genetics , protein kinase a , transcription factor , gene , amino acid , bacteria , fusion protein , mutant , recombinant dna
Two‐component signal transduction systems (TCS), consisting of a sensor histidine protein kinase and its cognate response regulator, are an important mode of environmental sensing in bacteria. Additionally, they have been found to regulate virulence determinants in several pathogens. Bacillus anthracis , the causative agent of anthrax and a bioterrorism agent, harbours 41 pairs of TCS. However, their role in its pathogenicity has remained largely unexplored. Here, we show that WalRK of B. anthracis forms a functional TCS which exhibits some species‐specific functions. Biochemical studies showed that domain variants of WalK, the histidine kinase, exhibit classical properties of autophosphorylation and phosphotransfer to its cognate response regulator WalR. Interestingly, these domain variants also show phosphatase activity towards phosphorylated WalR, thereby making WalK a bifunctional histidine kinase/phosphatase. An in silico regulon determination approach, using a consensus binding sequence from Bacillus subtilis , provided a list of 30 genes that could form a putative WalR regulon in B. anthracis . Further, electrophoretic mobility shift assay was used to show direct binding of purified WalR to the upstream regions of three putative regulon candidates, an S‐layer protein EA1, a cell division ABC transporter FtsE and a sporulation histidine kinase KinB3. Our work lends insight into the species‐specific functions and mode of action of B. anthracis WalRK.