A protein export pathway involving Escherichia coli porins.
Escherichia coli export the protein YebF into the extracellular medium by a two-step process. However, as no general outer membrane protein secretion system common to all E. coli strains has been reported, the mechanism of export has remained unclear. Herein, we identify the outer membrane proteins OmpF, OmpC, and OmpX as central to the YebF export mechanism using both genetic and planar lipid bilayer experiments. The nuclear magnetic resonance structural ensemble of YebF reveals a cystatin-like fold consisting of a structured core and an extended dynamic surface in a state of conformational exchange. This surface, conserved throughout YebF orthologs of Enterobacteriaceae, may facilitate the porin-mediated transport of YebF as amino acid substitutions of dynamic residues reduced secretion to the extracellular medium. Our results demonstrate that OmpF and OmpC not only operate to import ions and protein toxins but may also contribute to the export of the YebF protein family.
Department of Biochemistry and Molecular Biology, 2350 Health Sciences Mall, University of British Columbia, Vancouver, BC V6T 1Z3, Canada.
Gerd
G
Prehna
Guijin
G
Zhang
Xiandi
X
Gong
Marek
M
Duszyk
Mark
M
Okon
Lawrence P
LP
McIntosh
Joel H
JH
Weiner
Natalie C J
NC
Strynadka
D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006867:Hydrolases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008051:Lipid Bilayers / Q000737:chemistry / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010957:Plasmids; D018272:Porins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017433:Protein Structure, Secondary; D021381:Protein Transport; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D055672:Static Electricity; D014169:Transformation, Bacterial
D001425:Bacterial Outer Membrane Proteins; D029968:Escherichia coli Proteins; D008051:Lipid Bilayers; C113724:OmpC protein; C109237:OmpF protein; D018272:Porins; D011994:Recombinant Proteins; C508772:YebF protein, E coli; C482905:OmpX protein, E coli; D006867:Hydrolases