title: Crystal structure of the transcriptional regulator Rv0678 of Mycobacterium tuberculosis.
abstract: Recent work demonstrates that the MmpL (mycobacterial membrane protein large) transporters are dedicated to the export of mycobacterial lipids for cell wall biosynthesis. An MmpL transporter frequently works with an accessory protein, belonging to the MmpS (mycobacterial membrane protein small) family, to transport these key virulence factors. One such efflux system in Mycobacterium tuberculosis is the MmpS5-MmpL5 transporter. The expression of MmpS5-MmpL5 is controlled by the MarR-like transcriptional regulator Rv0678, whose open reading frame is located downstream of the mmpS5-mmpL5 operon. To elucidate the structural basis of Rv0678 regulation, we have determined the crystal structure of this regulator, to 1.64 Å resolution, revealing a dimeric two-domain molecule with an architecture similar to members of the MarR family of transcriptional regulators. Rv0678 is distinct from other MarR regulators in that its DNA-binding and dimerization domains are clustered together. These two domains seemingly cooperate to bind an inducing ligand that we identified as 2-stearoylglycerol, which is a fatty acid glycerol ester. The structure also suggests that the conformational change leading to substrate-mediated derepression is primarily caused by a rigid body rotational motion of the entire DNA-binding domain of the regulator toward the dimerization domain. This movement results in a conformational state that is incompatible with DNA binding. We demonstrate using electrophoretic mobility shift assays that Rv0678 binds to the mmpS5-mmpL5, mmpS4-mmpL4, and the mmpS2-mmpL2 promoters. Binding by Rv0678 was reversed upon the addition of the ligand. These findings provide new insight into the mechanisms of gene regulation in the MarR family of regulators.
authors.affiliation: From the Department of Chemistry and.
authors.forename: Abhijith
authors.initials: A
authors.lastname: Radhakrishnan
authors.affiliation: From the Department of Chemistry and.
authors.forename: Nitin
authors.initials: N
authors.lastname: Kumar
authors.affiliation: the Department of Molecular Microbiology and Immunology, Oregon Health and Sciences University, Portland, Oregon 97239, and.
authors.forename: Catherine C
authors.initials: CC
authors.lastname: Wright
authors.affiliation: the Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011.
authors.forename: Tsung-Han
authors.initials: TH
authors.lastname: Chou
authors.affiliation: From the Department of Chemistry and.
authors.forename: Marios L
authors.initials: ML
authors.lastname: Tringides
authors.affiliation: From the Department of Chemistry and.
authors.forename: Jani Reddy
authors.initials: JR
authors.lastname: Bolla
authors.affiliation: From the Department of Chemistry and.
authors.forename: Hsiang-Ting
authors.initials: HT
authors.lastname: Lei
authors.affiliation: the 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: the Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011.
authors.forename: Chih-Chia
authors.initials: CC
authors.lastname: Su
authors.affiliation: the Department of Molecular Microbiology and Immunology, Oregon Health and Sciences University, Portland, Oregon 97239, and.
authors.forename: Georgiana E
authors.initials: GE
authors.lastname: Purdy
authors.affiliation: From the Department of Chemistry and the Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, ewyu@iastate.edu.
authors.forename: Edward W
authors.initials: EW
authors.lastname: Yu
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D018360:Crystallography, X-Ray; D017931:DNA Primers; D019281:Dimerization; D008969:Molecular Sequence Data; D009169:Mycobacterium tuberculosis / Q000737:chemistry / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid
chemical_list: D017931:DNA Primers
keywords: Bacterial Transcription; Crystal Structure; Fatty Acid Transport; Infectious Diseases; MarR Family Regulators; Mycobacterial Membrane Protein Large; Mycobacterial Membrane Protein Small; Mycobacterium tuberculosis; Rv0678; Transcriptional Regulation
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