Crystal structures explain functional properties of two E. coli porins.

Department of Structural Biology, University of Basel, Switzerland.

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.

PMID: 1380671 [PubMed - indexed for MEDLINE]