title: Cation selectivity is a conserved feature in the OccD subfamily of Pseudomonas aeruginosa.
abstract: To achieve the uptake of small, water-soluble nutrients, Pseudomonas aeruginosa, a pathogenic Gram-negative bacterium, employs substrate-specific channels located within its outer membrane. In this paper, we present a detailed description of the single-channel characteristics of six members of the outer membrane carboxylate channel D (OccD) subfamily. Recent structural studies showed that the OccD proteins share common features, such as a closely related, monomeric, 18-stranded β-barrel conformation and large extracellular loops, which are folded back into the channel lumen. Here, we report that the OccD proteins displayed single-channel activity with a unitary conductance covering an unusually broad range, between 20 and 670pS, as well as a diverse gating dynamics. Interestingly, we found that cation selectivity is a conserved trait among all members of the OccD subfamily, bringing a new distinction between the members of the OccD subfamily and the anion-selective OccK channels. Conserved cation selectivity of the OccD channels is in accord with an increased specificity and selectivity of these proteins for positively charged, carboxylate-containing substrates.
authors: Department of Physics, Syracuse University, Syracuse, NY 13244-1130, USA.
authors: Jiaming
authors: J
authors: Liu
authors: Aaron J
authors: AJ
authors: Wolfe
authors: Elif
authors: E
authors: Eren
authors: Jagamya
authors: J
authors: Vijayaraghavan
authors: Mridhu
authors: M
authors: Indic
authors: Bert
authors: B
authors: van den Berg
authors: Liviu
authors: L
authors: Movileanu
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry* / Q000235:genetics; D002412:Cations; D003001:Cloning, Molecular; D008051:Lipid Bilayers; D011550:Pseudomonas aeruginosa / Q000737:chemistry*
chemical_list: D001425:Bacterial Outer Membrane Proteins; D002412:Cations; D008051:Lipid Bilayers