The bacterial dicarboxylate transporter VcINDY uses a two-domain elevator-type mechanism

Nat Struct Mol Biol. 2016 Mar;23(3):256-63. doi: 10.1038/nsmb.3166. Epub 2016 Feb 1.


Secondary transporters use alternating-access mechanisms to couple uphill substrate movement to downhill ion flux. Most known transporters use a 'rocking bundle' motion, wherein the protein moves around an immobile substrate-binding site. However, the glutamate-transporter homolog GltPh translocates its substrate-binding site vertically across the membrane, through an 'elevator' mechanism. Here, we used the 'repeat swap' approach to computationally predict the outward-facing state of the Na(+)/succinate transporter VcINDY, from Vibrio cholerae. Our model predicts a substantial elevator-like movement of VcINDY's substrate-binding site, with a vertical translation of ~15 Å and a rotation of ~43°. Our observation that multiple disulfide cross-links completely inhibit transport provides experimental confirmation of the model and demonstrates that such movement is essential. In contrast, cross-links across the VcINDY dimer interface preserve transport, thus revealing an absence of large-scale coupling between protomers.

Publication types

  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Dicarboxylic Acid Transporters / chemistry*
  • Dicarboxylic Acid Transporters / metabolism*
  • Models, Biological
  • Models, Chemical
  • Models, Molecular
  • Molecular Dynamics Simulation
  • Vibrio cholerae / enzymology*


  • Dicarboxylic Acid Transporters