Zhang Zhemin, Maharjan Rakesh, Gregor William D, Klenotic Philip A, Yu Edward W
Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA.
Sci Adv. 2025 Aug 15;11(33):eadx1129. doi: 10.1126/sciadv.adx1129. Epub 2025 Aug 13.
We coexpressed the mycobacterial membrane protein large 5 (MmpL5) transporter and MmpS5 adaptor proteins in and defined their structures from detergent-solubilized crude membranes. We observed that MmpL5 presents as a monomer in complex with the cytosolic meromycolate extension acyl carrier protein M (AcpM), where these AcpM-MmpL5 complexes generate regular two-dimensional arrays. We also provide structural information to show that MmpL5 assembles as a trimer that interacts with MmpS5 and AcpM to form the tripartite complex AcpM-MmpL5-MmpS5 that spans both the inner and outer membranes of the mycobacterium. In addition, we found that MmpL5 and AcpM are able to form the trimeric AcpM-MmpL5 complex. The structural data reveal that the full-length MmpL5 trimer is capable of spanning the entire mycobacterial cell envelope to transport substrates. However, this assembly requires the presence of MmpS5 to stabilize secondary structural features of the MmpL5 periplasmic subdomains.
我们在[具体内容缺失]中共表达了分枝杆菌膜蛋白大5(MmpL5)转运蛋白和MmpS5衔接蛋白,并从去污剂溶解的粗膜中确定了它们的结构。我们观察到,MmpL5与胞质分枝菌酸延伸酰基载体蛋白M(AcpM)形成复合物时呈单体形式,其中这些AcpM-MmpL5复合物形成规则的二维阵列。我们还提供了结构信息,表明MmpL5组装成三聚体,与MmpS5和AcpM相互作用,形成跨越分枝杆菌内膜和外膜的三方复合物AcpM-MmpL5-MmpS5。此外,我们发现MmpL5和AcpM能够形成三聚体AcpM-MmpL5复合物。结构数据表明,全长MmpL5三聚体能够跨越整个分枝杆菌细胞壁以转运底物。然而,这种组装需要MmpS5的存在来稳定MmpL5周质亚结构域的二级结构特征。