title: Structure-Function Profile of MmpL3, the Essential Mycolic Acid Transporter from Mycobacterium tuberculosis.
abstract: The MmpL family of proteins translocates complex (glyco)lipids and siderophores across the cell envelope of mycobacteria and closely related Corynebacteriaceae and plays important roles in the biogenesis of the outer membrane of these organisms. Despite their significance in the physiology and virulence of Mycobacterium tuberculosis, and from the perspective of developing novel antituberculosis agents, little is known about their structure and mechanism of translocation. In this study, the essential mycobacterial mycolic acid transporter, MmpL3, and its orthologue in Corynebacterium glutamicum, CmpL1, were investigated as prototypical MmpL proteins to gain insight into the transmembrane topology, tertiary and quaternary structures, and functional regions of this transporter family. The combined genetic, biochemical, and biophysical studies indicate that MmpL3 and CmpL1 are structurally similar to Gram-negative resistance-nodulation and division efflux pumps. They harbor 12 transmembrane segments interrupted by two large soluble periplasmic domains and function as homotrimers to export long-chain (C22-C90) mycolic acids, possibly in their acetylated form, esterified to trehalose. The mapping of a number of functional residues within the middle region of the transmembrane domain of MmpL3 shows a striking overlap with mutations associated with resistance to MmpL3 inhibitors. The results suggest that structurally diverse inhibitors of MmpL3 all target the proton translocation path of the transporter and that multiresistance to these inhibitors is enabled by conformational changes in MmpL3.
authors.affiliation: Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-1682, USA.
authors.forename: Juan Manuel
authors.initials: JM
authors.lastname: Belardinelli
authors.affiliation: Biochimie et Médecine Moléculaire, Université de Montréal, CP 6128, Station Centre-Ville, Montréal, Quebec, H3C 3J7, Canada.|Groupe d'Étude des Protéines Membranaires (GÉPROM), Université de Montréal, CP 6128, Station Centre-Ville, Montréal, Quebec, H3C 3J7, Canada.
authors.forename: Amira
authors.initials: A
authors.lastname: Yazidi
authors.affiliation: University of Oklahoma, Department of Chemistry and Biochemistry, 101 Stephenson Parkway, Norman, OK 73019, USA.
authors.forename: Liang
authors.initials: L
authors.lastname: Yang
authors.affiliation: Groupe d'Étude des Protéines Membranaires (GÉPROM), Université de Montréal, CP 6128, Station Centre-Ville, Montréal, Quebec, H3C 3J7, Canada.|Department of Anatomy and Cell Biology, McGill University, 3640 University Street, Montréal, Quebec, H3A 2B2, Canada.
authors.forename: Lucien
authors.initials: L
authors.lastname: Fabre
authors.affiliation: Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-1682, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.affiliation: Biochimie et Médecine Moléculaire, Université de Montréal, CP 6128, Station Centre-Ville, Montréal, Quebec, H3C 3J7, Canada.
authors.forename: Benoit
authors.initials: B
authors.lastname: Jacques
authors.affiliation: Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-1682, USA.
authors.forename: Shiva Kumar
authors.initials: SK
authors.lastname: Angala
authors.affiliation: Groupe d'Étude des Protéines Membranaires (GÉPROM), Université de Montréal, CP 6128, Station Centre-Ville, Montréal, Quebec, H3C 3J7, Canada.|Department of Anatomy and Cell Biology, McGill University, 3640 University Street, Montréal, Quebec, H3A 2B2, Canada.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Rouiller
authors.affiliation: University of Oklahoma, Department of Chemistry and Biochemistry, 101 Stephenson Parkway, Norman, OK 73019, USA.
authors.forename: Helen I
authors.initials: HI
authors.lastname: Zgurskaya
authors.affiliation: Biochimie et Médecine Moléculaire, Université de Montréal, CP 6128, Station Centre-Ville, Montréal, Quebec, H3C 3J7, Canada.|Groupe d'Étude des Protéines Membranaires (GÉPROM), Université de Montréal, CP 6128, Station Centre-Ville, Montréal, Quebec, H3C 3J7, Canada.
authors.forename: Jurgen
authors.initials: J
authors.lastname: Sygusch
authors.affiliation: Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-1682, USA.
authors.forename: Mary
authors.initials: M
authors.lastname: Jackson
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D048230:Corynebacterium glutamicum / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006801:Humans; D026901:Membrane Transport Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D015394:Molecular Structure; D009169:Mycobacterium tuberculosis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009171:Mycolic Acids / Q000737:chemistry / Q000378:metabolism*; D000072417:Protein Domains; D014376:Tuberculosis / Q000382:microbiology
chemical_list: D001426:Bacterial Proteins; D026901:Membrane Transport Proteins; C000599913:MmpL3 protein, Mycobacterium tuberculosis; D009171:Mycolic Acids
keywords: MmpL3; Mycobacterium; acyltrehaloses; lipid translocation; mycolic acids; tuberculosis