Probing the oligomeric state and interaction surfaces of Fukutin-I in dilauroylphosphatidylcholine bilayers

Eur Biophys J. 2012 Feb;41(2):199-207. doi: 10.1007/s00249-011-0773-5. Epub 2011 Nov 11.

Abstract

Fukutin-I is localised to the endoplasmic reticulum or Golgi apparatus within the cell, where it is believed to function as a glycosyltransferase. Its localisation within the cell is thought to to be mediated by the interaction of its N-terminal transmembrane domain with the lipid bilayers surrounding these compartments, each of which possesses a distinctive lipid composition. However, it remains unclear at the molecular level how the interaction between the transmembrane domains of this protein and the surrounding lipid bilayer drives its retention within these compartments. In this work, we employed chemical cross-linking and fluorescence resonance energy transfer measurements in conjunction with multiscale molecular dynamics simulations to determine the oligomeric state of the protein within dilauroylphosphatidylcholine bilayers to identify interactions between the transmembrane domains and to ascertain any role these interactions may play in protein localisation. Our studies reveal that the N-terminal transmembrane domain of Fukutin-I exists as dimer within dilauroylphosphatidylcholine bilayers and that this interaction is driven by interactions between a characteristic TXXSS motif. Furthermore residues close to the N-terminus that have previously been shown to play a key role in the clustering of lipids are shown to also play a major role in anchoring the protein in the membrane.

MeSH terms

  • Amino Acid Sequence
  • Cell Membrane / chemistry
  • Cell Membrane / metabolism
  • Cross-Linking Reagents / pharmacology
  • Fluorescence Resonance Energy Transfer
  • Lipid Bilayers / chemistry*
  • Lipid Bilayers / metabolism*
  • Membrane Proteins / chemistry*
  • Membrane Proteins / metabolism*
  • Molecular Dynamics Simulation
  • Molecular Sequence Data
  • Peptide Fragments / chemistry
  • Peptide Fragments / metabolism
  • Phosphatidylcholines / chemistry*
  • Phosphatidylcholines / metabolism
  • Protein Binding
  • Protein Multimerization*
  • Protein Structure, Quaternary
  • Protein Structure, Tertiary
  • Surface Properties

Substances

  • Cross-Linking Reagents
  • Lipid Bilayers
  • Membrane Proteins
  • Peptide Fragments
  • Phosphatidylcholines
  • 1,2-dilauroylphosphatidylcholine