Peptidoglycan-associated outer membrane protein Mep45 of rumen anaerobe Selenomonas ruminantium forms a non-specific diffusion pore via its C-terminal transmembrane domain

Seiji Kojima, Kanako Hayashi, Saeko Tochigi, Tomonobu Kusano, Jun Kaneko, Yoshiyuki Kamio

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

The major outer membrane protein Mep45 of Selenomonas ruminantium, an anaerobic Gramnegative bacterium, comprises two distinct domains: the N-terminal S-layer homologous (SLH) domain that protrudes into the periplasm and binds to peptidoglycan, and the remaining C-terminal transmembrane domain, whose function has been unknown. Here, we solubilized and purified Mep45 and characterized its function using proteoliposomes reconstituted with Mep45. We found that Mep45 forms a nonspecific diffusion channel via its C-terminal region. The channel was permeable to solutes smaller than a molecular weight of roughly 600, and the estimated pore radius was 0.58 nm. Truncation of the SLH domain did not affect the channel property. On the basis of the fact that Mep45 is the most abundant outer membrane protein in S. ruminantium, we conclude that Mep45 serves as a main pathway through which small solutes diffuse across the outer membrane of this bacterium.

Original languageEnglish
Pages (from-to)1954-1959
Number of pages6
JournalBioscience, Biotechnology and Biochemistry
Volume80
Issue number10
DOIs
Publication statusPublished - 2016

Keywords

  • Channel
  • Gram-negative bacteria
  • Outer membrane
  • Porin
  • Rumen

ASJC Scopus subject areas

  • Biotechnology
  • Analytical Chemistry
  • Biochemistry
  • Applied Microbiology and Biotechnology
  • Molecular Biology
  • Organic Chemistry

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