Structure-function analysis of MmpL7-mediated lipid transport in mycobacteria.
Structure-function analysis of MmpL7-mediated lipid transport in mycobacteria.
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DOI：
10.1016/j.tcsw.2021.100062
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发表时间：
2021-12
期刊：
影响因子：
--
通讯作者：
Bhatt A
中科院分区：
文献类型：
--
作者：
Moolla N;Bailo R;Marshall R;Bavro VN;Bhatt A
分枝杆菌膜蛋白Large（MmpL 7）是结核分枝杆菌中输出毒力脂质--邻苯二甲酸二蜡酯（PDIM）所需的耐药性-结瘤-分裂（RND）家族转运蛋白。使用相关的疫苗株牛分枝杆菌BCG的无效突变体，我们表明，MmpL 7也参与运输的结构相关的酚糖脂（PGL），这也是由高毒力M。结核分枝杆菌HN 878株中不存在，结核病H37 Rv.此外，我们生成了M的计算机模型。结核病MmpL 7，揭示MmpL 7作为MmpL家族内的功能异常值，缺少典型的质子中继签名序列，表明它采用尚未鉴定的能量耦合机制进行运输。此外，我们的分析表明，周质转运蛋白结构域2插入（PD 2-插入），它不共享任何可识别的同源性，是高度α-螺旋的性质，这表明一个组织类似于所看到的hopanoid PD 3/4结构域。使用M。牛BCG mmpL 7突变体与mmpL 7突变等位基因的功能互补，我们能够鉴定跨膜结构域TM 4和TM 10中存在的残基，以及在PDIM转运中起关键作用的PD 2结构域插入物，在某些情况下，PDIM的生物合成。
Mycobacterial membrane protein Large (MmpL7) is a Resistance-Nodulation-Division (RND) family transporter required for the export of the virulence lipid, phthiocerol dimycocerosate (PDIM), in Mycobacterium tuberculosis. Using a null mutant of the related, vaccine strain Mycobacterium bovis BCG, we show that MmpL7 is also involved in the transport of the structurally related phenolic glycolipid (PGL), which is also produced by the hypervirulent M. tuberculosis strain HN878, but absent in M. tuberculosis H37Rv. Furthermore, we generated an in silico model of M. tuberculosis MmpL7 that revealed MmpL7 as a functional outlier within the MmpL-family, missing a canonical proton-relay signature sequence, suggesting that it employs a yet-unidentified mechanism for energy coupling for transport. In addition, our analysis demonstrates that the periplasmic porter domain 2 insert (PD2-insert), which doesn't share any recognisable homology, is highly alpha-helical in nature, suggesting an organisation similar to that seen in the hopanoid PD3/4 domains. Using the M. bovis BCG mmpL7 mutant for functional complementation with mutated alleles of mmpL7, we were able to identify residues present in the transmembrane domains TM4 and TM10, and the PD2 domain insert that play a crucial role in PDIM transport, and in certain cases, biosynthesis of PDIM.