1hxx
OMPF PORIN MUTANT Y106F
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OverviewOverview
The channel constriction of OmpF porin, a pore protein in the bacterial, outer membrane, is highly charged due to the presence of three arginines, (R42, R82, and R132) and two acidic residues (D113 and E117). The, influence of these charges on ion conductance, ion selectivity, and, voltage gating has been studied with mutants D113N/E117Q, R42A/R82A/R132A/D113N/E117Q, and V18K/G131K, which were designed to remove, or add protein charge at the channel constriction. The crystal structures, revealed no or only local changes compared to wild-type OmpF, thus, allowing a comparative study. The single-channel conductance of the, isosteric D113N/E117Q variant was found to be 2-fold reduced, and that of, the pentuple mutant was 70% of the wild-type value, despite a considerably, larger pore cross section. Ion selectivity was drastically altered by the, mutations with cation/anion permeability ratios ranging from 1 to 12. Ion, flow through these and eight other mutants, which have been characterized, previously, was simulated by Brownian dynamics based on the detailed, crystal structures. The calculated ion selectivity and relative channel, conductance values agree well with the experimental data. This, demonstrates that ion translocation through porin is mainly governed by, pore geometry and charge, the two factors that are properly represented in, the simulations.
About this StructureAbout this Structure
1HXX is a Single protein structure of sequence from Escherichia coli with C8E as ligand. Full crystallographic information is available from OCA.
ReferenceReference
Role of charged residues at the OmpF porin channel constriction probed by mutagenesis and simulation., Phale PS, Philippsen A, Widmer C, Phale VP, Rosenbusch JP, Schirmer T, Biochemistry. 2001 May 29;40(21):6319-25. PMID:11371193
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