title: Structural Basis for the Regulation of the MmpL Transporters of Mycobacterium tuberculosis.
abstract: The mycobacterial cell wall is critical to the virulence of these pathogens. Recent work shows that the MmpL (mycobacterial membrane protein large) family of transporters contributes to cell wall biosynthesis by exporting fatty acids and lipidic elements of the cell wall. The expression of the Mycobacterium tuberculosis MmpL proteins is controlled by a complex regulatory network, including the TetR family transcriptional regulators Rv3249c and Rv1816. Here we report the crystal structures of these two regulators, revealing dimeric, two-domain molecules with architecture consistent with the TetR family of regulators. Buried extensively within the C-terminal regulatory domains of Rv3249c and Rv1816, we found fortuitous bound ligands, which were identified as palmitic acid (a fatty acid) and isopropyl laurate (a fatty acid ester), respectively. Our results suggest that fatty acids may be the natural ligands of these regulatory proteins. Using fluorescence polarization and electrophoretic mobility shift assays, we demonstrate the recognition of promoter and intragenic regions of multiple mmpL genes by these proteins. Binding of palmitic acid renders these regulators incapable of interacting with their respective operator DNAs, which will result in derepression of the corresponding mmpL genes. Taken together, these experiments provide new perspectives on the regulation of the MmpL family of transporters.
authors.affiliation: Departments of Physics and Astronomy, Iowa State University, Ames, Iowa 50011.
authors.forename: Jared A
authors.initials: JA
authors.lastname: Delmar
authors.affiliation: Departments of Physics and Astronomy, Iowa State University, Ames, Iowa 50011.
authors.forename: Tsung-Han
authors.initials: TH
authors.lastname: Chou
authors.affiliation: Department of Molecular Microbiology and Immunology, Oregon Health and Sciences University, Portland, Oregon 97239.
authors.forename: Catherine C
authors.initials: CC
authors.lastname: Wright
authors.affiliation: Department of Molecular Microbiology and Immunology, Oregon Health and Sciences University, Portland, Oregon 97239.
authors.forename: Meredith H
authors.initials: MH
authors.lastname: Licon
authors.affiliation: Department of Molecular Microbiology and Immunology, Oregon Health and Sciences University, Portland, Oregon 97239.
authors.forename: Julia K
authors.initials: JK
authors.lastname: Doh
authors.affiliation: Departments of Chemistry, Iowa State University, Ames, Iowa 50011.
authors.forename: Abhijith
authors.initials: A
authors.lastname: Radhakrishnan
authors.affiliation: Departments of Chemistry, Iowa State University, Ames, Iowa 50011.
authors.forename: Nitin
authors.initials: N
authors.lastname: Kumar
authors.affiliation: Departments of Chemistry, Iowa State University, Ames, Iowa 50011.
authors.forename: Hsiang-Ting
authors.initials: HT
authors.lastname: Lei
authors.affiliation: Departments of Chemistry, Iowa State University, Ames, Iowa 50011.
authors.forename: Jani Reddy
authors.initials: JR
authors.lastname: Bolla
authors.affiliation: Northeastern Collaborative Access Team and Department of Chemistry and Chemical Biology, Cornell University, Argonne National Laboratory, Argonne, Illinois 60439.
authors.forename: Kanagalaghatta R
authors.initials: KR
authors.lastname: Rajashankar
authors.affiliation: Departments of Physics and Astronomy, Iowa State University, Ames, Iowa 50011.
authors.forename: Chih-Chia
authors.initials: CC
authors.lastname: Su
authors.affiliation: Department of Molecular Microbiology and Immunology, Oregon Health and Sciences University, Portland, Oregon 97239.
authors.forename: Georgiana E
authors.initials: GE
authors.lastname: Purdy
authors.affiliation: Departments of Physics and Astronomy, Iowa State University, Ames, Iowa 50011; Departments of Chemistry, Iowa State University, Ames, Iowa 50011. Electronic address: ewyu@iastate.edu.
authors.forename: Edward W
authors.initials: EW
authors.lastname: Yu
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D018360:Crystallography, X-Ray; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000378:metabolism*; D009169:Mycobacterium tuberculosis / Q000378:metabolism*; D011487:Protein Conformation
chemical_list: D001426:Bacterial Proteins; D026901:Membrane Transport Proteins
keywords: Mycobacterium tuberculosis; Rv3249c; TetR family regulators; bacterial pathogenesis; cell wall; mycobacterial membrane protein large; mycobacterial membrane protein small; transcription repressor; x-ray crystallography