UMMS Affiliation

Program in Molecular Medicine

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Document Type



Bacterial Outer Membrane Proteins; Ion Channels; Multigene Family; Porins; Pseudomonas aeruginosa


Biochemistry, Biophysics, and Structural Biology | Life Sciences | Medicine and Health Sciences


Many Gram-negative bacteria, including human pathogens such as Pseudomonas aeruginosa, do not have large-channel porins. This results in an outer membrane (OM) that is highly impermeable to small polar molecules, making the bacteria intrinsically resistant towards many antibiotics. In such microorganisms, the majority of small molecules are taken up by members of the OprD outer membrane protein family. Here we show that OprD channels require a carboxyl group in the substrate for efficient transport, and based on this we have renamed the family Occ, for outer membrane carboxylate channels. We further show that Occ channels can be divided into two subfamilies, based on their very different substrate specificities. Our results rationalize how certain bacteria can efficiently take up a variety of substrates under nutrient-poor conditions without compromising membrane permeability. In addition, they explain how channel inactivation in response to antibiotics can cause resistance but does not lead to decreased fitness.

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Copyright: © 2012 Eren et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

DOI of Published Version



Eren E, Vijayaraghavan J, Liu J, Cheneke BR, Touw DS, et al. (2012) Substrate Specificity within a Family of Outer Membrane Carboxylate Channels. PLoS Biol 10(1): e1001242. doi:10.1371/journal.pbio.1001242. Link to article on publisher's site

Journal/Book/Conference Title

PLoS biology

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Link to Article in PubMed

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