Crystal structures explain functional properties of two E. coli porins. |
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Authors: | S W Cowan T Schirmer G Rummel M Steiert R Ghosh R A Pauptit J N Jansonius J P Rosenbusch |
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Institution: | Department of Structural Biology, University of Basel, Switzerland. |
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Abstract: | Porins form aqueous channels that aid the diffusion of small hydrophilic molecules across the outer membrane of Gram-negative bacteria. The crystal structures of matrix porin and phosphoporin both reveal trimers of identical subunits, each subunit consisting of a 16-stranded anti-parallel beta-barrel containing a pore. A long loop inside the barrel contributes to a constriction of the channel where the charge distribution affects ion selectivity. The structures explain at the molecular level functional characteristics and their alterations by known mutations. |
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