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Biogenesis of a putative channel protein, ComEC, required for DNA uptake: membrane topology, oligomerization and formation of disulphide bonds
Author(s) -
Draskovic Irena,
Dubnau David
Publication year - 2005
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/j.1365-2958.2004.04430.x
Subject(s) - biology , transmembrane protein , membrane protein , biogenesis , transmembrane domain , biochemistry , membrane topology , microbiology and biotechnology , dna , biophysics , topology (electrical circuits) , membrane , gene , receptor , mathematics , combinatorics
Summary ComEC is a putative channel protein for DNA uptake in Bacillus subtilis and other genetically transformable bacteria. Membrane topology studies suggest a model of ComEC as a multispanning membrane protein with seven transmembrane segments (TMSs), and possibly with one laterally inserted amphipathic helix. We show that ComEC contains an intramolecular disulphide bond in its N‐terminal extracellular loop (between the residues C131 and C172), which is required for the stability of the protein, and is probably introduced by BdbDC, a pair of competence‐induced oxidoreductase proteins. By in vitro cross‐linking using native cysteine residues we show that ComEC forms an oligomer. The oligomerization surface includes a transmembrane segment, TMS‐G, near the cytoplasmic C‐terminus of ComEC.