Treponema pallidum TroA is a periplasmic zinc-binding protein with a helical backbone

Nat Struct Biol. 1999 Jul;6(7):628-33. doi: 10.1038/10677.


The crystal structure of recombinant TroA, a zinc-binding protein component of an ATP-binding cassette transport system in Treponema pallidum, was determined at a resolution of 1.8 A. The organization of the protein is largely similar to other periplasmic ligand-binding proteins (PLBP), in that two independent globular domains interact with each other to create a zinc-binding cleft between them. The structure has one bound zinc pentavalently coordinated to residues from both domains. Unlike previous PLBP structures that have an interdomain hinge composed of beta-strands, the N- and C-domains of TroA are linked by a single long backbone helix. This unique backbone helical conformation was possibly adopted to limit the hinge motion associated with ligand exchange.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • ATP-Binding Cassette Transporters / chemistry*
  • ATP-Binding Cassette Transporters / physiology
  • Bacterial Proteins / chemistry
  • Binding Sites
  • Carrier Proteins / chemistry
  • Escherichia coli Proteins*
  • Models, Molecular
  • Molecular Sequence Data
  • Periplasm / chemistry*
  • Periplasmic Binding Proteins*
  • Photosynthetic Reaction Center Complex Proteins / chemistry
  • Photosystem I Protein Complex*
  • Protein Structure, Secondary
  • Treponema pallidum / chemistry*
  • X-Ray Diffraction
  • Zinc / metabolism*


  • ATP-Binding Cassette Transporters
  • Bacterial Proteins
  • Carrier Proteins
  • Escherichia coli Proteins
  • MalE protein, E coli
  • PSI-A protein, Synechococcus
  • Periplasmic Binding Proteins
  • Photosynthetic Reaction Center Complex Proteins
  • Photosystem I Protein Complex
  • TroA protein, Treponema pallidum
  • Zinc

Associated data

  • PDB/1TOA