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Phosphatase activity of the histidine kinases ensures pathway specificity of the ChrSA and HrrSA two‐component systems in C orynebacterium glutamicum
Author(s) -
Hentschel Eva,
Mack Christina,
Gätgens Cornelia,
Bott Michael,
Brocker Melanie,
Frunzke Julia
Publication year - 2014
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.12633
Subject(s) - phosphatase , biology , kinase , histidine , component (thermodynamics) , biochemistry , histidine kinase , protein serine threonine kinases , enzyme , microbiology and biotechnology , protein kinase a , physics , thermodynamics
Summary The majority of bacterial genomes encode a high number of two‐component systems controlling gene expression in response to a variety of different stimuli. The G ram‐positive soil bacterium C orynebacterium glutamicum contains two homologous two‐component systems ( TCS ) involved in the haem‐dependent regulation of gene expression. Whereas the HrrSA system is crucial for utilization of haem as an alternative iron source, ChrSA is required to cope with high toxic haem levels. In this study, we analysed the interaction of HrrSA and ChrSA in C . glutamicum . Growth of TCS mutant strains, in vitro phosphorylation assays and promoter assays of P hrtBA and P hmuO fused to eyfp revealed cross‐talk between both systems. Our studies further indicated that both kinases exhibit a dual function as kinase and phosphatase. Mutation of the conserved glutamine residue in the putative phosphatase motif DxxxQ of HrrS and ChrS resulted in a significantly increased activity of their respective target promoters ( P hmuO and P hrtBA respectively). Remarkably, phosphatase activity of both kinases was shown to be specific only for their cognate response regulators. Altogether our data suggest the phosphatase activity of HrrS and ChrS as key mechanism to ensure pathway specificity and insulation of these two homologous systems.