MECHANISMS OF SOLUTE TRANSPORT THROUGH OUTER-MEMBRANE PORINS - BURNING DOWN THE HOUSE

Porins mediate the uptake of nutrients across the outer membrane of Gr am-negative bacteria. For general porins like OmpF, electrophysicoloig cal experiments now establish that the charged residues within their c hannels primarily modulate pore selectivity, rather than voltage-gated switching between open and closed dates. Recent studies on the maltop orin, LamB, solidify the importance of its 'greasy slide' aromatic res idues during sugar transport, and suggest the involvement of L9, in th e exterior vestibule, as the initial maltodextrin binding site. The ap plication of biophysical methodologies to the TonB-dependent porin, Fe pA, ostensibly reveal the opening and closing of its channel during li gand uptake, a phenomenon that was predicted but not previously demons trated.