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

Journal Article · Fri Oct 04 00:00:00 EDT 2013 · Biochimica et Biophysica Acta. Biomembranes

DOI:https://doi.org/10.1016/j.bbamem.2013.09.020· OSTI ID:1134706

Rathnayake, Sewwandi S. ^[1]; Mirheydari, Mona ^[1]; Schulte, Adam ^[1]; Gillahan, James E. ^[1]; Gentit, Taylor ^[1]; Phillips, Ashley N. ^[1]; Okonkwo, Rose K. ^[1]; Burger, Koert N.J. ^[2]; Mann, Elizabeth K. ^[1]; Vaknin, David ^[3]; Bu, Wei ^[3]; Agra-Kooijman, Dena Mae ^[1]; Kooijman, Edgar E. ^[1]

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1. Kent State Univ., Kent, OH (United States)
2. Utrecht Univ. (Netherlands)
3. Ames Lab., Ames, IA (United States)

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 a model exchangeable apolipoprotein with significant implications for its mammalian counterparts. (C) 2013 Elsevier B.V. All rights reserved.

• Research Organization: Ames Lab., Ames, IA (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: AC02-07CH11358
• OSTI ID: 1134706
• Report Number(s): IS-J 8241
• Journal Information: Biochimica et Biophysica Acta. Biomembranes, Vol. 1838; ISSN 0005-2736
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

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