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Title: Insertion of apoLp-III into a lipid monolayer is more favorable for saturated, more ordered, acyl-chains

Neutral lipid transport in mammals is complicated involving many types of apolipoprotein. The exchangeable apolipoproteins mediate the transfer of hydrophobic lipids between tissues and particles, and bind to cell surface receptors. Amphipathic a-helices form a common structural motif that facilitates their lipid binding and exchangeability. ApoLp-III, the only exchangeable apolipoprotein found in insects, is a model amphipathic a:helix bundle protein and its three dimensional structure and function mimics that of the mammalian proteins apoE and apoAI. Even the intracellular exchangeable lipid droplet protein TIP47/perilipin 3 contains an a-helix bundle domain with high structural similarity to that of apoE and apoLp-III. Here, we investigated the interaction of apoLp-III from Locusta migratoria with lipid monolayers. Consistent with earlier work we find that insertion of apoLp-III into fluid lipid monolayers is highest for diacylglycerol. We observe a preference for saturated and more highly ordered lipids, suggesting a new mode of interaction for amphipathic a-helix bundles. X-ray reflectivity shows that apoLp-III unfolds at a hydrophobic interface and flexible loops connecting the amphipathic cc-helices stay in solution. X-ray diffraction indicates that apoLp-III insertion into diacylglycerol monolayers induces additional ordering of saturated acyl-chains. These results thus shed important new insight into the protein-lipid interactions of amore » model exchangeable apolipoprotein with significant implications for its mammalian counterparts. (C) 2013 Elsevier B.V. All rights reserved.« less
 [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [1] ;  [3] ;  [3] ;  [1] ;  [1]
  1. Kent State Univ., Kent, OH (United States)
  2. Utrecht Univ. (Netherlands)
  3. Ames Lab., Ames, IA (United States)
Publication Date:
OSTI Identifier:
Report Number(s):
IS-J 8241
Journal ID: ISSN 0005-2736
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Biochimica et Biophysica Acta. Biomembranes; Journal Volume: 1838
Research Org:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
36 MATERIALS SCIENCE; binding, curvature, Diacylglycerol, elastic properties, Exchangeable apolipoprotein, IN-VIVO, insect apolipophorin-iii, Insertion isotherm, interaction, langmuir monolayer, locusta-migratoria, manduca-sexta, phospholipid monolayer, Protein-lipid, reflectivity and diffraction, spontaneous, x-ray