Structural basis for the regulation of the MmpL transporters of Mycobacterium tuberculosis

Jared A. Delmar, Tsung Han Chou, Catherine C. Wright, Meredith H. Licon, Julia K. Doh, Abhijith Radhakrishnan, Nitin Kumar, Hsiang Ting Lei, Jani Reddy Bolla, Kanagalaghatta R. Rajashankar, Chih Chia Su, Georgiana E. Purdy, Edward W. Yu

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

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, twodomain 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.

Original languageEnglish (US)
Pages (from-to)28559-28574
Number of pages16
JournalJournal of Biological Chemistry
Volume290
Issue number47
DOIs
StatePublished - Nov 20 2015

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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