Impaired α-TTP-PIPs interaction underlies familial vitamin E deficiency

Science. 2013 May 31;340(6136):1106-10. doi: 10.1126/science.1233508. Epub 2013 Apr 18.

Abstract

α-Tocopherol (vitamin E) transfer protein (α-TTP) regulates the secretion of α-tocopherol from liver cells. Missense mutations of some arginine residues at the surface of α-TTP cause severe vitamin E deficiency in humans, but the role of these residues is unclear. Here, we found that wild-type α-TTP bound phosphatidylinositol phosphates (PIPs), whereas the arginine mutants did not. In addition, PIPs in the target membrane promoted the intermembrane transfer of α-tocopherol by α-TTP. The crystal structure of the α-TTP-PIPs complex revealed that the disease-related arginine residues interacted with phosphate groups of the PIPs and that the PIPs binding caused the lid of the α-tocopherol-binding pocket to open. Thus, PIPs have a role in promoting the release of a ligand from a lipid-transfer protein.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Substitution
  • Arginine / chemistry
  • Arginine / genetics
  • Arginine / metabolism
  • Carrier Proteins / chemistry
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism*
  • Crystallography, X-Ray
  • Humans
  • Mutation
  • Phosphatidylinositol 4,5-Diphosphate / metabolism*
  • Protein Structure, Secondary
  • Vitamin E Deficiency / metabolism*
  • alpha-Tocopherol / metabolism

Substances

  • Carrier Proteins
  • Phosphatidylinositol 4,5-Diphosphate
  • alpha-tocopherol transfer protein
  • Arginine
  • alpha-Tocopherol

Associated data

  • PDB/3W67
  • PDB/3W68