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Updated: May 13, 2026

Applying an Inducible Expression System to Study Interference of Bacterial Virulence Factors with Intracellular Signaling
Published on: June 25, 2015
Extracellular signal protein triggering the proteolytic activation of a developmental transcription factor in B.
A E Hofmeister1, A Londoño-Vallejo, E Harry
1Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
Abstract:
We present biochemical evidence for an intercellular signal transduction pathway in B. subtilis. This pathway governs the conversion of the proprotein pro-sigma E to mature transcription factor sigma E. Proteolytic processing is mediated by the membrane protein SpollGA and is triggered by the inferred extracellular signal protein SpollR. A factor in conditioned medium from B. subtilis cells engineered to produce SpollR during growth triggered processing in protoplasts of B. subtilis cells that had been engineered to produce SpollGA and pro-sigma E. The factor was also detected in, and partially purified from, extracts of SpollR-producing cells of E. coli. We speculate that SpollGA is both a receptor and a protease and the SpollR interacts with SpollGA on the outside of the cytoplasmic membrane, activating the intracellular protease domain of SpollGA.
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