Electron paramagnetic resonance spectroscopy of site-directed spin labels reveals the structural heterogeneity in the N-terminal domain of apoA-I in solution

Jens O Lagerstedt, Madhu S. Budamagunta, Michael N. Oda, John C Voss

Research output: Contribution to journalArticlepeer-review

57 Citations (SciVal)

Abstract

Apolipoprotein A-I (apoA-I) is the major protein constituent of high density lipoprotein (HDL) and plays a central role in phospholipid and cholesterol metabolism. This 243-residue long protein is remarkably flexible and assumes numerous lipid-dependent conformations. Consequently, definitive structural determination of lipid-free apoA-I in solution has been difficult. Using electron paramagnetic spectroscopy of site-directed spin labels in the N-terminal domain of apoA-I (residues 1-98) we have mapped a mixture of secondary structural elements, the composition of which is consistent with findings from other in-solution methods. Based on side chain mobility and their accessibility to polar and non-polar spin relaxers, the precise location of secondary elements for amino acids 14-98 was determined for both lipid-free and lipid-bound apoA-I. Based on intermolecular dipolar coupling at positions 26, 44, and 64, these secondary structural elements were arranged into a tertiary fold to generate a structural model for lipid-free apoA-I in solution.

Original languageEnglish
Pages (from-to)9143-9
JournalJournal of Biological Chemistry
Volume282
Issue number12
DOIs
Publication statusPublished - 2007 Mar 23
Externally publishedYes

Keywords

  • Apolipoprotein A-I
  • Crystallization
  • Dimerization
  • Electron Spin Resonance Spectroscopy
  • Humans
  • Lipids
  • Models, Molecular
  • Molecular Conformation
  • Mutagenesis
  • Protein Binding
  • Protein Conformation
  • Protein Folding
  • Protein Structure, Secondary
  • Protein Structure, Tertiary
  • Spin Labels
  • Journal Article
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

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