title: Biogenesis of a putative channel protein, ComEC, required for DNA uptake: membrane topology, oligomerization and formation of disulphide bonds.
abstract: 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.
authors.affiliation: Public Health Research Institute at International Center for Public Health, 225 Warren Street, Newark, NJ 07103, USA.
authors.forename: Irena
authors.initials: I
authors.lastname: Draskovic
authors.forename: David
authors.initials: D
authors.lastname: Dubnau
mesh_terms: D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D003198:Computer Simulation; D003545:Cysteine / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D019281:Dimerization; D004220:Disulfides / Q000737:chemistry; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011490:Protein Disulfide Reductase (Glutathione) / Q000378:metabolism; D014169:Transformation, Bacterial
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D004220:Disulfides; D008565:Membrane Proteins; C450430:BdbC protein, Bacillus subtilis; C450431:BdbD protein, Bacillus subtilis; D011490:Protein Disulfide Reductase (Glutathione); D003545:Cysteine