Rooke Jessica L, Icke Christopher, Wells Timothy J, Rossiter Amanda E, Browning Douglas F, Morris Faye C, Leo Jack C, Schütz Monika S, Autenrieth Ingo B, Cunningham Adam F, Linke Dirk, Henderson Ian R
Institute for Molecular Bioscience, University of Queensland, St Lucia, QLD, Australia.
Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom.
Front Microbiol. 2021 Feb 23;12:628879. doi: 10.3389/fmicb.2021.628879. eCollection 2021.
The BAM complex in is composed of five proteins, BamA-E. BamA and BamD are essential for cell viability and are required for the assembly of β-barrel outer membrane proteins. Consequently, BamA and BamD are indispensable for secretion via the classical autotransporter pathway (Type 5a secretion). In contrast, BamB, BamC, and BamE are not required for the biogenesis of classical autotransporters. Recently, we demonstrated that TamA, a homologue of BamA, and its partner protein TamB, were required for efficient secretion of proteins via the classical autotransporter pathway. The trimeric autotransporters are a subset of the Type 5-secreted proteins. Unlike the classical autotransporters, they are composed of three identical polypeptide chains which must be assembled together to allow secretion of their cognate passenger domains. In contrast to the classical autotransporters, the role of the Bam and Tam complex components in the biogenesis of the trimeric autotransporters has not been investigated fully. Here, using the trimeric autotransporter SadA and the structurally similar YadA protein of spp., we identify the importance of BamA and BamD in the biogenesis of the trimeric autotransporters and reveal that BamB, BamC, BamE, TamA and TamB are not required for secretion of functional passenger domain on the cell surface.
The secretion of trimeric autotransporters (TAA's) has yet to be fully understood. Here we show that efficient secretion of TAAs requires the BamA and D proteins, but does not require BamB, C or E. In contrast to classical autotransporter secretion, neither trimeric autotransporter tested required TamA or B proteins to be functionally secreted.
中的BAM复合物由五种蛋白质BamA - E组成。BamA和BamD对细胞活力至关重要，并且是β - 桶状外膜蛋白组装所必需的。因此，BamA和BamD对于通过经典自转运途径（5a型分泌）的分泌是不可或缺的。相比之下，经典自转运蛋白的生物合成不需要BamB、BamC和BamE。最近，我们证明了BamA的同源物TamA及其伴侣蛋白TamB是通过经典自转运途径有效分泌蛋白质所必需的。三聚体自转运蛋白是5型分泌蛋白的一个子集。与经典自转运蛋白不同，它们由三条相同的多肽链组成，这些多肽链必须组装在一起才能使其同源乘客结构域得以分泌。与经典自转运蛋白相反，Bam和Tam复合物成分在三聚体自转运蛋白生物合成中的作用尚未得到充分研究。在这里，我们使用三聚体自转运蛋白SadA和结构相似的嗜肺军团菌属的YadA蛋白，确定了BamA和BamD在三聚体自转运蛋白生物合成中的重要性，并揭示BamB、BamC、BamE、TamA和TamB对于细胞表面功能性乘客结构域的分泌不是必需的。
三聚体自转运蛋白（TAA）的分泌尚未完全了解。在这里我们表明，TAA的有效分泌需要BamA和D蛋白，但不需要BamB、C或E。与经典自转运蛋白分泌不同，所测试的两种三聚体自转运蛋白在功能分泌时都不需要TamA或B蛋白。
