Crystal structure of human apolipoprotein A-I: insights into its protective effect against cardiovascular diseases.

Academic Article

Abstract

  • Despite three decades of extensive studies on human apolipoprotein A-I (apoA-I), the major protein component in high-density lipoproteins, the molecular basis for its antiatherogenic function is elusive, in part because of lack of a structure of the full-length protein. We describe here the crystal structure of lipid-free apoA-I at 2.4 A. The structure shows that apoA-I is comprised of an N-terminal four-helix bundle and two C-terminal helices. The N-terminal domain plays a prominent role in maintaining its lipid-free conformation, indicating that mutants with truncations in this region form inadequate models for explaining functional properties of apoA-I. A model for transformation of the lipid-free conformation to the high-density lipoprotein-bound form follows from an analysis of solvent-accessible hydrophobic patches on the surface of the structure and their proximity to the hydrophobic core of the four-helix bundle. The crystal structure of human apoA-I displays a hitherto-unobserved array of positively and negatively charged areas on the surface. Positioning of the charged surface patches relative to hydrophobic regions near the C terminus of the protein offers insights into its interaction with cell-surface components of the reverse cholesterol transport pathway and antiatherogenic properties of this protein. This structure provides a much-needed structural template for exploration of molecular mechanisms by which human apoA-I ameliorates atherosclerosis and inflammatory diseases.
  • Keywords

  • Apolipoprotein A-I, Cardiotonic Agents, Cardiovascular Diseases, Crystallography, Humans, Hydrophobic and Hydrophilic Interactions, Lipids, Protein Structure, Secondary
  • Digital Object Identifier (doi)

    Author List

  • Ajees AA; Anantharamaiah GM; Mishra VK; Hussain MM; Murthy HMK
  • Start Page

  • 2126
  • End Page

  • 2131
  • Volume

  • 103
  • Issue

  • 7