Membrane topology of the Escherichia coli TolR protein required for cell envelope integrity.
TolR is a 142-amino-acid protein required for the import of colicins and bacteriophage and for maintenance of cell envelope integrity. The topology of TolR in the inner membrane was analyzed by two methods. First, bacteria expressing a series of TolR-beta-galactosidase, TolR-alkaline phosphatase, and TolR-beta-lactamase fusions were assayed for the appropriate enzymatic activity. Second, the accessibility of TolR to proteinase K was determined in permeabilized cells and everted vesicles with an antibody elicited against the carboxyl-terminal 70% of TolR. The results are consistent with TolR spanning the inner membrane once via residues 23 to 43 and with the carboxyl-terminal moiety being exposed to the periplasm. Quantitative studies with the anti-TolR antibody indicated the presence of 2 x 10(3) to 3 x 10(3) TolR molecules per cell.
Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710.
M M
MM
Muller
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A
Vianney
J C
JC
Lazzaroni
R E
RE
Webster
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Portalier
D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002462:Cell Membrane / Q000737:chemistry / Q000648:ultrastructure; D002463:Cell Membrane Permeability; D010450:Endopeptidases / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000648:ultrastructure*; D029968:Escherichia coli Proteins; D015151:Immunoblotting; D008565:Membrane Proteins; D011487:Protein Conformation
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; C060794:tolR protein, E coli; D010450:Endopeptidases