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Antagonistic effects of dual PTS‐catalysed phosphorylation on the Bacillus subtilis transcriptional activator LevR
Author(s) -
MartinVerstraete Isabelle,
Charrier Véronique,
Stülke Jörg,
Galinier Anne,
Erni Bernhard,
Rapoport Georges,
Deutscher Josef
Publication year - 1998
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 - 10.1046/j.1365-2958.1998.00781.x
Subject(s) - pep group translocation , phosphorylation , bacillus subtilis , catabolite repression , biology , operon , mutant , biochemistry , activator (genetics) , enzyme , serine , lac operon , kinase , phosphoenolpyruvate carboxykinase , gene , gene expression , bacteria , genetics
LevR, which controls the expression of the lev operon of Bacillus subtilis , is a regulatory protein containing an N‐terminal domain similar to the NifA/NtrC transcriptional activator family and a C‐terminal domain similar to the regulatory part of bacterial anti‐terminators, such as BglG and LicT. Here, we demonstrate that the activity of LevR is regulated by two phosphoenolpyruvate (PEP)‐dependent phosphorylation reactions catalysed by the phosphotransferase system (PTS), a transport system for sugars, polyols and other sugar derivatives. The two general components of the PTS, enzyme I and HPr, and the two soluble, sugar‐specific proteins of the lev ‐PTS, LevD and LevE, form a signal transduction chain allowing the PEP‐dependent phosphorylation of LevR, presumably at His‐869. This phosphorylation seems to inhibit LevR activity and probably regulates the induction of the lev operon. Mutants in which His‐869 of LevR has been replaced with a non‐phosphorylatable alanine residue exhibited constitutive expression from the lev promoter, as do levD or levE mutants. In contrast, PEP‐dependent phosphorylation of LevR in the presence of only the general components of the PTS, enzyme I and HPr, regulates LevR activity positively. This phosphorylation most probably occurs at His‐585. Mutants in which His‐585 has been replaced with an alanine had lost stimulation of LevR activity and PEP‐dependent phosphorylation by enzyme I and HPr. This second phosphorylation of LevR at His‐585 is presumed to play a role in carbon catabolite repression.