Conformational adaptation of apolipoprotein A-I to discretely sized phospholipid complexes. Biochemistry 2007 Jul 03;46(26):7811-21
Date
06/15/2007Pubmed ID
17563120Pubmed Central ID
PMC2553278DOI
10.1021/bi700384tScopus ID
2-s2.0-34347356570 (requires institutional sign-in at Scopus site) 66 CitationsAbstract
The conformational constraints for apoA-I bound to recombinant phospholipid complexes (rHDL) were attained from a combination of chemical cross-linking and mass spectrometry. Molecular distances were then used to refine models of lipid-bound apoA-I on both 80 and 96 A diameter rHDL particles. To obtain molecular constraints on the protein bound to phospholipid complexes, three different lysine-selective homo-bifunctional cross-linkers with increasing spacer arm lengths (i.e., 7.7, 12.0, and 16.1 A) were reacted with purified, homogeneous recombinant 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) apoA-I rHDL complexes of each diameter. Cross-linked dimeric apoA-I products were separated from monomeric apoprotein using 12% SDS-PAGE, then subjected to in-gel trypsin digest, and identified by MS/MS sequencing. These studies aid in the refinement of our previously published molecular model of two apoA-I molecules bound to approximately 150 molecules of POPC and suggest that the protein hydrophobic interactions at the N- and C-terminal domains decrease as the number of phospholipid molecules or "lipidation state" of apoA-I increases. Thus, it appears that these incremental changes in the interaction between the N- and C-terminal ends of apoA-I stabilize its tertiary conformation in the lipid-free state as well as allowing it to unfold and sequester discrete amounts of phospholipid molecules.
Author List
Bhat S, Sorci-Thomas MG, Tuladhar R, Samuel MP, Thomas MJAuthor
Mary Sorci Thomas PhD Professor in the Medicine department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
Apolipoprotein A-ICross-Linking Reagents
Electrophoresis, Polyacrylamide Gel
Humans
Lipoproteins, HDL
Models, Molecular
Phosphatidylcholines
Phospholipids
Protein Conformation
Recombinant Proteins
Succinimides
Tandem Mass Spectrometry
