Conformation of a peptide encompassing the proton translocation channel of vacuolar H+-ATPase

W.L. Vos, L.S. Vermeer, M.A. Hemminga

Research output: Contribution to journalArticleAcademicpeer-review

11 Citations (Scopus)

Abstract

The structural properties of a crucial transmembrane helix for proton translocation in vacuolar ATPase are studied using double site-directed spin-labeling combined with electron spin resonance (ESR) (or electron paramagnetic resonance) and circular dichroism spectroscopy in sodium dodecyl sulfate micelles. For this purpose, we use a synthetic peptide derived from transmembrane helix 7 of subunit a from the yeast Saccharomyces cerevisiae vacuolar proton-translocating ATPase that contains two natural cysteine residues suitable for spin-labeling. The interspin distance is calculated using a second-moment analysis of the methanethiosulfonate spin-label ESR spectra at 150 K. Molecular dynamics simulation is used to study the effect of the side-chain dynamics and backbone dynamics on the interspin distance. Based on the combined results from ESR, circular dichroism, and molecular dynamics simulation we conclude that the peptide forms a dynamic -helix. We discuss this finding in the light of current models for proton translocation. A novel role for a buried charged residue (H729) is proposed.
Original languageEnglish
Pages (from-to)138-146
JournalBiophysical Journal
Volume92
DOIs
Publication statusPublished - 2007

Keywords

  • yeast v-atpase
  • molecular-dynamics simulations
  • electron-spin-resonance
  • coiled-coils
  • alpha-helix
  • pi-helix
  • protein
  • subunit
  • domain
  • receptor

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