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Stoichiometry and perturbation studies of the LiaFSR system of B acillus subtilis
Author(s) -
Schrecke Karen,
Jordan Sina,
Mascher Thorsten
Publication year - 2013
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.12130
Subject(s) - response regulator , histidine kinase , two component regulatory system , biology , operon , phosphatase , histidine , regulator , phosphorylation , kinase , biochemistry , phosphate , microbiology and biotechnology , biophysics , gene , enzyme , escherichia coli , bacterial protein , mutant
Summary The response regulator/histidine kinase pair LiaRS of B acillus subtilis , together with its membrane‐bound inhibitor protein LiaF , constitutes an envelope stress‐sensing module that is conserved in F irmicutes bacteria. LiaR positively autoregulates the expression of the liaIH ‐ liaGFSR operon from a strictly LiaR ‐dependent promoter ( P liaI ). A comprehensive perturbation analysis revealed that the functionality of the LiaFSR system is very susceptible to alterations of its protein composition and amounts. A genetic analysis indicates a LiaF : LiaS : LiaR ratio of 18:4:1. An excess of LiaS over LiaR was subsequently verified by quantitative W estern analysis. This stoichiometry, which is crucial to maintain a functional Lia system, differs from any other two‐component system studied to date, in which the response regulator is present in excess over the histidine kinase. Moreover, we demonstrate that LiaS is a bifunctional histidine kinase that acts as a phosphatase on LiaR in the absence of a suitable stimulus. An increased amount of LiaR – both in the presence and in the absence of LiaS – leads to a strong induction of P liaI activity due to phosphorylation of the response regulator by acetyl phosphate. Our data demonstrate that LiaRS , in contrast to other two‐component systems, is non‐robust with regard to perturbations of its stoichiometry.