9syv

Symmetric hexameric MmpS4-MmpL4 complex from Mycobacterium tuberculosis

spinqualitylabelsall models 9syv, resolution 2.89Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 9syv is a 6 chain structure with sequence from Mycobacterium tuberculosis. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Electron Microscopy, Resolution 2.89Å Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function MMPL4_MYCTU Part of an export system, which is required for biosynthesis and secretion of siderophores (PubMed:23431276). Essential for normal replication during the active-growth phase of the murine tuberculosis model (PubMed:15908378). Publication Abstract from PubMed Mycobacterium tuberculosis contains thirteen Mycobacterial membrane protein Large (MmpL) transporters, which belong to the family of secondary active RND transporters. MmpL4 and MmpL5, together with their operon partners MmpS4 and MmpS5, export the mycobacterial siderophore mycobactin and the last resort TB drug bedaquiline. Recently, we determined a structure of the MmpL4 monomer in complex with desferrated mycobactin, which lacked a functionally essential coiled-coil domain predicted to extend far into the periplasm. Here, we present a cryo-EM structure of the hexameric (MmpS4)(3)-(MmpL4)(3) complex, which was enabled by rational disulfide cross-links based on AlphaFold predictions. We observed density for the coiled-coil domain, which protrudes into the periplasmic space at an angle of around 60 degrees relative to the symmetry axis of the MmpL4 trimer. In the context of the hexameric complex, MmpL4's conformation differs strikingly from the one observed for monomeric MmpL4, which includes formation of a large cavity in the periplasmic domain and rearrangements of conserved proton coupling residues at the transmembrane domain. Our work provides an experimental workflow to obtain single particle cryo-EM structures of labile multiprotein complexes by AlphaFold-informed stabilization of predicted protein interfaces. Structural elucidation of the hexameric MmpS4-MmpL4 complex from Mycobacterium tuberculosis.,Earp JC, Lichti NP, Garaeva AA, Meikle V, Niederweis M, Seeger MA bioRxiv [Preprint]. 2026 Jan 7:2026.01.07.698164. doi: , 10.64898/2026.01.07.698164. PMID:41542548 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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