Wakai Taketo, Kano Chie, Karsens Harma, Kok Jan, Yamamoto Naoyuki
Core Technology Laboratories, Asahi Quality and Innovations, Ltd., 5-11-10 Fuchinobe, Chuo-ku, Sagamihara-shi, Kanagawa, Japan.
Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Linnaeusborg, Nijenborgh 7, Groningen, The Netherlands.
Biosci Microbiota Food Health. 2021;40(1):33-42. doi: 10.12938/bmfh.2020-005. Epub 2020 Sep 17.
surface layer proteins (SLPs) self-assemble into a monolayer that is non-covalently bound to the outer surface of the cells. There they are in direct contact with the environment, environmental stressors and gut components of the host in which the organism resides. The role of SLPs is not entirely understood, although SLPs seem to be essential for bacterial growth. We constructed three L-92 strains, each expressing a mutant of the most abundant SLP, SlpA. Each carried a 12-amino acid c-myc epitope substitution at a different position in the protein. A strain was also obtained that expressed the SlpA paralog SlpB from an originally silent gene. All four strains behaved differently with respect to growth under various stress conditions, such as the presence of salt, ox gall or ethanol, suggesting that SlpA affects stress tolerance in L-92. Also, the four mutants showed differential binding ability to human host cell proteins such as uromodulin or dendritic cell (DC)-specific intercellular adhesion molecule-3 grabbing non-integrin (DC-SIGN). Furthermore, co-culture of murine immature DCs with a mutant strain expressing one of the recombinant SlpA proteins changed the concentrations of the cytokines IL-10 and IL-12. Our data suggest that SlpA and SlpB of participate in bacterial stress tolerance and binding to uromodulin or DC-SIGN, possibly leading to effective immune-modification.
表面层蛋白（SLPs）自组装形成单层，该单层与细胞外表面非共价结合。在那里，它们直接与生物体所驻留的宿主的环境、环境应激源和肠道成分接触。尽管SLPs似乎对细菌生长至关重要，但其作用尚未完全明确。我们构建了三株L-92菌株，每株都表达最丰富的SLP即SlpA的突变体。每株在该蛋白的不同位置都带有一个12个氨基酸的c-myc表位替换。还获得了一株从原本沉默的基因表达SlpA旁系同源物SlpB的菌株。在各种应激条件下，如存在盐、牛胆汁或乙醇时，所有这四株菌株在生长方面表现各异，这表明SlpA影响L-92中的应激耐受性。此外，这四个突变体对人宿主细胞蛋白如尿调节蛋白或树突状细胞（DC）特异性细胞间粘附分子3结合非整合素（DC-SIGN）显示出不同的结合能力。此外，将小鼠未成熟DC与表达其中一种重组SlpA蛋白的突变菌株共培养会改变细胞因子IL-10和IL-12的浓度。我们的数据表明，的SlpA和SlpB参与细菌应激耐受性以及与尿调节蛋白或DC-SIGN的结合，可能导致有效的免疫修饰。
