PMID:8702816

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Citation

Lou, KL, Saint, N, Prilipov, A, Rummel, G, Benson, SA, Rosenbusch, JP and Schirmer, T (1996) Structural and functional characterization of OmpF porin mutants selected for larger pore size. I. Crystallographic analysis. J. Biol. Chem. 271:20669-75

Abstract

OmpF porin is a nonspecific pore protein from the outer membrane of Escherichia coli. Previously, a set of mutants was selected that allow the passage of long maltodextrins that do not translocate through the wild-type pore. Here, we describe the crystal structures of four point mutants and one deletion mutant from this set; their functional characterization is reported in the accompanying paper (Saint, N., Lou, K.-L., Widmer, C., Luckey, M., Schirmer, T., Rosenbusch, J. P. (1996) J. Biol. Chem. 271, 20676-20680). All mutations have a local effect on the structure of the pore constriction and result in a larger pore cross-section. Substitution of each of the three closely packed arginine residues at the pore constriction (Arg-42, Arg-82, and Arg-132) by shorter uncharged residues causes rearrangement of the adjacent basic residues. This demonstrates mutual stabilization of these residues in the wild-type porin. Deletion of six residues from the internal loop (Delta109-114) results in disorder of seven adjacent residues but does not alter the structure of the beta-barrel framework. Thus, the large hollow beta-barrel motif can be regarded as an autonomous structure.

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Keywords

Amino Acid Sequence; Bacterial Outer Membrane Proteins/chemistry; Bacterial Outer Membrane Proteins/genetics; Base Sequence; Crystallography, X-Ray; DNA Primers/chemistry; Escherichia coli; Hydrogen Bonding; Ion Channel Gating; Ion Channels/chemistry; Ion Channels/genetics; Models, Molecular; Molecular Sequence Data; Protein Structure, Tertiary; Structure-Activity Relationship

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