The purified NmpC outer membrane protein from Escherichia coli, when incorporated into planar lipid bilayers, gave rise to channels with a single-channel conductance of 1.8 nS in 1 M KCl. This suggests that the NmpC protein is a porin.

Different isoforms of the adenine nucleotide translocase (ANT) are expressed in a tissue-specific manner. It was assumed that ANT-1 and ANT-2 co-exist in every single mitochondrion and might be differently distributed within the membrane structures that constitute the peripheral inner membrane or the crista membrane. To discriminate between ANT originating from peripheral or from cristal inner ...

We studied the current rectification properties and selectivity of class 1 porin (PorA) from Neisseria meningitidis (strain H44/76 Delta 3 Delta 4) reconstituted in planar lipid membranes varying salt concentrations and pH. PorA channel shows voltage gating with a characteristic time remarkably longer than other porins. Its current-voltage asymmetry, evaluated as the current rectification ratio...

Determination of the rates of diffusion of beta-lactam antibiotics through purified Pseudomonas aeruginosa porins C, D2, and E in liposomes yielded the following results. (i) The rates of carbapenem (imipenem and meropenem) diffusion through the protein D2 pore were roughly 2 to 70 times higher than those through other porin pores. It is not clear why the protein D2 pore allowed rapid diffusion...

Bacterial outer membrane porins have a robust beta-barrel structure and therefore show potential for use as stochastic sensors based on single-molecule detection. The monomeric porin OmpG is especially attractive compared with multisubunit proteins because appropriate modifications of the pore can be easily achieved by mutagenesis. However, the gating of OmpG causes transient current blockades ...

Earlier studies have shown that the major porin species in Pseudomonas aeruginosa outer membrane is protein F (OprF), which produces channels wider than those produced by Escherichia coli porins. In contrast, Yoshihara and Nakae ((1989) J. Biol. Chem. 264, 6297-6301) reported that protein F has no pore-forming activity as measured by the flux of L-arabinose, and that the channels in P. aerugino...

The Escherichia coli OmpF (outer-membrane protein F; matrix porin) is a homotrimeric beta-barrel and a member of the bacterial porin superfamily. It is the best characterized porin protein, but has resisted attempts to refold it efficiently in vitro. In the present paper, we report the discovery of detergent-based folding conditions, including dodecylglucoside, which can create pure samples of ...

Porins are trimers of beta-barrels that form channels for ions and other hydrophilic solutes in the outer membrane of Gram-negative bacteria. The X-ray structures of OmpF and PhoE show that each monomeric pore is constricted by an extracellular loop that folds into the channel vestibule, a motif that is highly conserved among bacterial porins. Electrostatic calculations have suggested that the ...

The mechanism of killing of Aeromonas hydrophila serum-sensitive strains in nonimmune serum by the complement classical pathway has been studied. The bacterial cell surface component that binds C1q more efficiently was identified as a major outer membrane protein of 39 kDa, presumably the porin II described by D. Jeanteur, N. Gletsu, F. Pattus, and J. T. Buckley (Mol. Microbiol. 6:3355-3363, 19...

The OprD family of specific porins in Pseudomonas aeruginosa comprises 19 members, some of which have been demonstrated to facilitate the uptake of specific compounds into the cell. The members of this family share considerable amino acid sequence similarity (46–57%), which is unusual among porin molecules. In this work, we sought to establish whether this sequence conservation was the basis fo...