Moolla Nabiela, Weaver Helen, Bailo Rebeca, Singh Albel, Bavro Vassiliy N, Bhatt Apoorva
School of Biosciences and Institute of Microbiology and Infection, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom.
School of Life Sciences, University of Essex, Colchester CO4 3SQ, United Kingdom.
Cell Surf. 2024 Oct 15;12:100132. doi: 10.1016/j.tcsw.2024.100132. eCollection 2024 Dec.
The virulence lipid phthiocerol dimycocerosate (PDIM) is exported by a complex mechanism that involves multiple proteins including the Resistance-Nodulation-Division (RND) transporter MmpL7 and the lipoprotein LppX. Here, we probe the role of the putative heterooligomeric ATP-Binding Cassette (ABC) transporter complex composed of DrrA, DrrB and DrrC in PDIM transport by constructing a set of individual null mutants of , and in the vaccine strain BCG. Loss of all three, or individual genes, all resulted in a complete loss of PDIM export to the outer envelope of the mycobacterial cell. Furthermore, guided by a bioinformatic analysis we interrogated specific signature residues within the DrrABC to demonstrate that it is indeed an ABC transporter, and our modelling, together with the mutagenesis identify it as a member of the Type V family of ABC exporters. We identify several unique structural elements of the transporter, including a non-canonical C-terminally inserted domain (CTD) structure within DrrA, which may account for its functional properties.
毒力脂质结核硬脂酸二霉菌酸酯（PDIM）通过一种复杂机制输出，该机制涉及多种蛋白质，包括耐药-固氮-细胞分裂（RND）转运蛋白MmpL7和脂蛋白LppX。在此，我们通过构建疫苗株卡介苗中drrA、drrB和drrC的一组单基因缺失突变体，探究由DrrA、DrrB和DrrC组成的假定异源寡聚ATP结合盒（ABC）转运蛋白复合物在PDIM转运中的作用。drrA、drrB和drrC这三个基因全部缺失，或单个drr基因缺失，均导致PDIM向分枝杆菌细胞外膜输出完全丧失。此外，在生物信息学分析的指导下，我们研究了DrrABC内的特定特征残基，以证明它确实是一种ABC转运蛋白，并且我们的建模以及诱变分析将其鉴定为ABC输出蛋白V型家族的成员。我们确定了该转运蛋白的几个独特结构元件，包括DrrA内一个非典型的C末端插入结构域（CTD）结构，这可能解释了其功能特性。
