Cryo-EM structure and resistance landscape of M. tuberculosis MmpL3: An emergent therapeutic target

• Published in: Structure (London) 2021-10, Vol.29 (10), p.1182-1191.e4
• Main Authors: Adams, Oliver, Deme, Justin C., Parker, Joanne L., Fowler, Philip W., Lea, Susan M., Newstead, Simon
• Format: Article
• Language: English
• Subjects: antitubercular; Bacterial Proteins - chemistry; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; cryo-EM; Cryoelectron Microscopy; drug resistance; Drug Resistance, Bacterial; LMNG; membrane protein; Membrane Transport Proteins - chemistry; Membrane Transport Proteins - genetics; Membrane Transport Proteins - metabolism; MmpL; MmpL3; Mutation; mycolic acid; RND transporter; Short; tuberculosis
• ISSN: 0969-2126; 1878-4186
• DOI: 10.1016/j.str.2021.06.013

Tuberculosis (TB) is the leading cause of death from a single infectious agent and in 2019 an estimated 10 million people worldwide contracted the disease. Although treatments for TB exist, continual emergence of drug-resistant variants necessitates urgent development of novel antituberculars. An important new target is the lipid transporter MmpL3, which is required for construction of the unique cell envelope that shields Mycobacterium tuberculosis (Mtb) from the immune system. However, a structural understanding of the mutations in Mtb MmpL3 that confer resistance to the many preclinical leads is lacking, hampering efforts to circumvent resistance mechanisms. Here, we present the cryoelectron microscopy structure of Mtb MmpL3 and use it to comprehensively analyze the mutational landscape of drug resistance. Our data provide a rational explanation for resistance variants local to the central drug binding site, and also highlight a potential alternative route to resistance operating within the periplasmic domain. [Display omitted] •Cryo-EM structure of M. tuberculosis MmpL3 determined at 3.0 Å resolution•An LMNG molecule within the periplasmic cavity suggests the TMM export pathway•Comprehensive structural mapping of resistance-conferring MmpL3 variants•Genome-mined MmpL3 mutations indicate minimal pre-existing resistance Adams et al. report a structure of the M. tuberculosis glycolipid transporter MmpL3, a protein essential to envelope biogenesis and an emergent therapeutic target. The structure reveals the probable lipid export pathway, and mapping of resistance-conferring mutations suggests the existence of multiple routes to preclinical inhibitor evasion.