Structural and functional characterization of OmpF porin mutants selected for larger pore size. II.. Functional characterization

Saint, N. and Lou, K. L. and Widmer, C. and Luckey, M. and Schirmer, T. and Rosenbusch, J. P.. (1996) Structural and functional characterization of OmpF porin mutants selected for larger pore size. II.. Functional characterization. Journal of Biological Chemistry, Vol. 271, H. 34. pp. 20676-20680.

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Official URL: http://edoc.unibas.ch/dok/A5258279

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The effects on the channel characteristics of four single amino acid substitutions in OmpF porin and of a deletion mutant in the constriction loop L3 have been studied. These mutations are all located in the narrow section of the channel of the protein that forms pores across the outer membrane of Escherichia coli. The single channel conductance of the deletion mutant (Delta109-114) is decreased by one third, whereas the point mutations do not exhibit significant deviations from that of the wild-type protein. The mutants exhibit drastic changes in ion selectivities. In the wild-type protein, the critical threshold potential (Vc), above which channels close reversibly, exhibits a strong pH dependence, with a titration point of approximately pH 7.7, which is abolished in all mutants studied here. Diffusion of six monosaccharides is little affected in the point mutants, while four disaccharides are taken up at highly increased rates by the deletion mutant. The functional results, presented here, are correlated to the x-ray structures of the mutants (Lou, K.-L., Saint, N., Prilipov, A., Rummel, G., Benson, S.A., Rosenbusch, J.P., and Schirmer, T. (1996) J. Biol. Chem. 271, 20669-20675). In most, but not all, cases, the structural changes explain the functional alterations observed.
Faculties and Departments:05 Faculty of Science > Departement Biozentrum > Structural Biology & Biophysics > Structural Biology (Schirmer)
UniBasel Contributors:Schirmer, Tilman
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:American Society of Biological Chemists
Note:Publication type according to Uni Basel Research Database: Journal article
Last Modified:22 Mar 2012 14:20
Deposited On:22 Mar 2012 13:20

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