TITLE:
Activation without Proteolysis of Anti-σ Factor RsiV of the Extracytoplasmic Function σ Factor σV in a Glucolipid-Deficient Mutant of Bacillus subtilis
AUTHORS:
Takahiro Seki, Kouji Matsumoto, Satoshi Matsuoka, Hiroshi Hara
KEYWORDS:
Anti-σ Factor, Bacillus subtilis, ECF σ Factor, Glucolipid, RsiV, σV, UgtP
JOURNAL NAME:
Advances in Microbiology,
Vol.7 No.4,
April
30,
2017
ABSTRACT: Extracytoplasmic function
(ECF) σ factors are a crucial link in the process of bacterial response to
environmental stresses, in which bacteria transmit information across the
cytoplasmic membrane. Among the seven ECF σ factors of Bacillus subtilis σV, which is sequestered by transmembrane anti-σ factor
RsiV under normal growth conditions, responds to lysozyme. When B. subtilis cells are challenged by lysozyme, the lysozyme-bound RsiV undergoes two
successive proteolysis steps, by a signal peptidase and RasP protease, and
releases σV. An unchallenged B. subtilis ugtP mutant lacking glucolipids exhibited higher σV activity than wild type. However, the activation occurred in the absence
of RasP, and no proteolysis of RsiV was observed. It is likely that a
conformational change, not proteolysis, of RsiV leads to this activation of σV in the absence of glucolipids. Replacement of the C-terminal region of
RsiV with that of RsiW, the cognate σ factor
of which, σW, is not activated in the ugtP mutant, indicated that the C-terminal extracytoplasmic region of RsiV was
necessary for the response to glucolipid deficiency.