Characterization of the first planctomycetal outer membrane protein identifies a channel in the outer membrane of the anammox bacterium Kuenenia stuttgartiensis.

Autor: van Teeseling MCF; Department of Microbiology, Institute for Water and Wetland Research, Faculty of Science, Radboud University, Nijmegen, The Netherlands. Electronic address: muriel.vanteeseling@uni-marburg.de., Benz R; Department of Life Sciences and Chemistry, Jacobs University, Bremen, Germany., de Almeida NM; Department of Microbiology, Institute for Water and Wetland Research, Faculty of Science, Radboud University, Nijmegen, The Netherlands., Jetten MSM; Department of Microbiology, Institute for Water and Wetland Research, Faculty of Science, Radboud University, Nijmegen, The Netherlands., Mesman RJ; Department of Microbiology, Institute for Water and Wetland Research, Faculty of Science, Radboud University, Nijmegen, The Netherlands., van Niftrik L; Department of Microbiology, Institute for Water and Wetland Research, Faculty of Science, Radboud University, Nijmegen, The Netherlands. Electronic address: l.vanniftrik@science.ru.nl.
Jazyk: angličtina
Zdroj: Biochimica et biophysica acta. Biomembranes [Biochim Biophys Acta Biomembr] 2018 Mar; Vol. 1860 (3), pp. 767-776. Date of Electronic Publication: 2017 Dec 27.
DOI: 10.1016/j.bbamem.2017.12.020
Abstrakt: Planctomycetes are a bacterial phylum known for their complex intracellular compartmentalization. While most Planctomycetes have two compartments, the anaerobic ammonium oxidizing (anammox) bacteria contain three membrane-enclosed compartments. In contrast to a long-standing consensus, recent insights suggested the outermost Planctomycete membrane to be similar to a Gram-negative outer membrane (OM). One characteristic component that differentiates OMs from cytoplasmic membranes (CMs) is the presence of outer membrane proteins (OMPs) featuring a β-barrel structure that facilitates passage of molecules through the OM. Although proteomic and genomic evidence suggested the presence of OMPs in several Planctomycetes, no experimental verification existed of the pore-forming function and localization of these proteins in the outermost membrane of these exceptional microorganisms. Here, we show via lipid bilayer assays that at least two typical OMP-like channel-forming proteins are present in membrane preparations of the anammox bacterium Kuenenia stuttgartiensis. One of these channel-forming proteins, the highly abundant putative OMP Kustd1878, was purified to homogeneity. Analysis of the channel characteristics via lipid bilayer assays showed that Kustd1878 forms a moderately cation-selective channel with a high current noise and an average single-channel conductance of about 170-190pS in 1M KCl. Antibodies were raised against the purified protein and immunogold localization indicated Kustd1878 to be present in the outermost membrane. Therefore, this work clearly demonstrates the presence of OMPs in anammox Planctomycetes and thus firmly adds to the emerging view that Planctomycetes have a Gram-negative cell envelope.
(Copyright © 2018 Elsevier B.V. All rights reserved.)
Databáze: MEDLINE
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