Membrane Protein Sequestering by Ionic Protein-Lipid Interactions

Nature. 2011 Oct 23;479(7374):552-5. doi: 10.1038/nature10545.

Abstract

Neuronal exocytosis is catalysed by the SNAP receptor protein syntaxin-1A, which is clustered in the plasma membrane at sites where synaptic vesicles undergo exocytosis. However, how syntaxin-1A is sequestered is unknown. Here we show that syntaxin clustering is mediated by electrostatic interactions with the strongly anionic lipid phosphatidylinositol-4,5-bisphosphate (PIP2). Using super-resolution stimulated-emission depletion microscopy on the plasma membranes of PC12 cells, we found that PIP2 is the dominant inner-leaflet lipid in microdomains about 73 nanometres in size. This high accumulation of PIP2 was required for syntaxin-1A sequestering, as destruction of PIP2 by the phosphatase synaptojanin-1 reduced syntaxin-1A clustering. Furthermore, co-reconstitution of PIP2 and the carboxy-terminal part of syntaxin-1A in artificial giant unilamellar vesicles resulted in segregation of PIP2 and syntaxin-1A into distinct domains even when cholesterol was absent. Our results demonstrate that electrostatic protein-lipid interactions can result in the formation of microdomains independently of cholesterol or lipid phases.

Publication types

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

MeSH terms

  • Animals
  • Cholesterol
  • Membrane Microdomains / chemistry*
  • Membrane Microdomains / metabolism
  • Microscopy, Confocal
  • Molecular Dynamics Simulation
  • Nerve Tissue Proteins / metabolism
  • PC12 Cells
  • Phosphatidylinositol 4,5-Diphosphate / chemistry*
  • Phosphatidylinositol 4,5-Diphosphate / metabolism*
  • Phosphoric Monoester Hydrolases / metabolism
  • Protein Binding*
  • Rats
  • Static Electricity*
  • Syntaxin 1 / chemistry*
  • Syntaxin 1 / metabolism*
  • Unilamellar Liposomes / chemistry
  • Unilamellar Liposomes / metabolism

Substances

  • Nerve Tissue Proteins
  • Phosphatidylinositol 4,5-Diphosphate
  • Stx1a protein, rat
  • Syntaxin 1
  • Unilamellar Liposomes
  • Cholesterol
  • synaptojanin
  • Phosphoric Monoester Hydrolases