The amino terminus of Pseudomonas aeruginosa outer membrane protein OprF forms channels in lipid bilayer membranes: correlation with a three-dimensional model.
Pseudomonas aeruginosa OprF forms 0.36-nS channels and, rarely, 2- to 5-nS channels in lipid bilayer membranes. We show that a protein comprising only the N-terminal 162-amino-acid domain of OprF formed the smaller, but not the larger, channels in lipid bilayers. Circular dichroism spectroscopy indicated that this protein folds into a beta-sheet-rich structure, and three-dimensional comparative modeling revealed that it shares significant structural similarity with the amino terminus of the orthologous protein Escherichia coli OmpA, which has been shown to form a beta-barrel. OprF and OmpA share only 15% identity in this domain, yet these results support the utility of modeling such widely divergent beta-barrel domains in three dimensions in order to reveal similarities not readily apparent through primary sequence comparisons. The model is used to further hypothesize why porin activity differs for the N-terminal domains of OprF and OmpA.
Brinkman
F S
FS
Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada.
Bains
M
M
Hancock
R E
RE
D000595:Amino Acid Sequence; D002462:Cell Membrane / Q000502:physiology* / Q000648:ultrastructure; D008051:Lipid Bilayers; D008958:Models, Molecular; D008969:Molecular Sequence Data; D018272:Porins / Q000737:chemistry* / Q000502:physiology*; D011487:Protein Conformation; D011550:Pseudomonas aeruginosa / Q000502:physiology*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D008051:Lipid Bilayers; D018272:Porins