Crystal structure of the cytoplasmic N-terminal domain of subunit I, a homolog of subunit a, of V-ATPase

J Mol Biol. 2011 Sep 9;412(1):14-21. doi: 10.1016/j.jmb.2011.07.014. Epub 2011 Jul 22.


Subunit "a" is associated with the membrane-bound (V(O)) complex of eukaryotic vacuolar H(+)-ATPase acidification machinery. It has also been shown recently to be involved in diverse membrane fusion/secretory functions independent of acidification. Here, we report the crystal structure of the N-terminal cytosolic domain from the Meiothermus ruber subunit "I" homolog of subunit a. The structure is composed of a curved long central α-helix bundle capped on both ends by two lobes with similar α/β architecture. Based on the structure, a reasonable model of its eukaryotic subunit a counterpart was obtained. The crystal structure and model fit well into reconstructions from electron microscopy of prokaryotic and eukaryotic vacuolar H(+)-ATPases, respectively, clarifying their orientations and interactions and revealing features that could enable subunit a to play a role in membrane fusion/secretion.

Publication types

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

MeSH terms

  • Binding Sites
  • Calmodulin / metabolism
  • Crystallography, X-Ray / methods*
  • Protein Binding
  • Protein Structure, Secondary
  • Protein Structure, Tertiary
  • Protein Subunits
  • SNARE Proteins / metabolism
  • Thermus / enzymology
  • Vacuolar Proton-Translocating ATPases / chemistry*
  • Vacuolar Proton-Translocating ATPases / genetics
  • Vacuolar Proton-Translocating ATPases / metabolism*


  • Calmodulin
  • Protein Subunits
  • SNARE Proteins
  • Vacuolar Proton-Translocating ATPases

Associated data

  • PDB/3RRK