Critical roles of a housekeeping sortase of probiotic Bifidobacterium bifidum in bacterium-host cell crosstalk

Eiji Ishikawa; Tetsuya Yamada; Kazuaki Yamaji; Masaki Serata; Daichi Fujii; Yoshinori Umesaki; Hirokazu Tsuji; Koji Nomoto; Masahiro Ito; Nobuhiko Okada; Masato Nagaoka; Atsushi Gomi

doi:10.1016/j.isci.2021.103363

Critical roles of a housekeeping sortase of probiotic Bifidobacterium bifidum in bacterium-host cell crosstalk

iScience. 2021 Oct 28;24(11):103363. doi: 10.1016/j.isci.2021.103363. eCollection 2021 Nov 19.

Authors

Affiliations

¹ Yakult Central Institute, 5-11 Izumi, Kunitachi-shi, Tokyo 186-8650, Japan.
² Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo 156-8502, Japan.
³ Department of Microbiology, School of Pharmacy, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan.

Abstract

Bifidobacterium bifidum YIT 10347 (BF-1) is adhesive in vitro. Here we studied the molecular aspects of the BF-1 adhesion process. We identified and characterized non-adhesive mutants and found that a class E housekeeping sortase was critical for the adhesion to mucin. These mutants were significantly less adhesive to GCIY cells than was the wild type (WT), which protected GCIY cells against acid treatment more than did a non-adhesive mutant. The non-adhesive mutants aberrantly accumulated precursors of putative sortase-dependent proteins (SDPs). Recombinant SDPs bound to mucin. Disruption of the housekeeping sortase influenced expression of SDPs and pilus components. Mutants defective in a pilin or in an SDP showed the same adhesion properties as WT. Therefore, multiple SDPs and pili seem to work cooperatively to achieve adhesion, and the housekeeping sortase is responsible for cell wall anchoring of its substrates to ensure their proper biological function.

Keywords: Evolutionary ecology; Microbiology; Microbiome.