The long-term goal of this research is to elucidate, in molecular terms, the structure-function relationships in human high density lipoproteins (HDL). This project focuses on the structure and function of apolipoprotein A-I. the major protein component of HDL. The main hypothesis we wish to test is that the three-dimensional structure of apo A-I in lipid-bound states consists of two domains: (l) an N-terminal domain which is compact, relatively stable yet conformationally flexible, which binds to lipid through hydrophobic anchoring residues in addition to the amphipathic (X-helices, and contains the specific LCAT activating region; and (2) a C-terminal domain which mediates oligomerization in solution, initial insertion of apo A-I into lipid aggregates, and retains nonspecific lipid binding and LCAT activating properties. To study the domain structure and functions of apo A-I we will prepare site-directed mutants and deletion mutants, as well as large, chemically produced fragments of plasma apo A-I and recombinant proapo A-I. These purified variants of apo A-I will then be investigated in terms of (a) their structure, stability, and oligomerization in aqueous solution and in 30% n-propanol (which induces a native-like structure in apo A-I); (b) their ability to interact with phospholipids on surfaces, in liposomes, and in reconstituted HDL (rHDL); (c) their structure in homogeneous rHDL; (d) their functions, in the defined rHDL, as activators of lecithin cholesterol acyltransferase and as mediators of binding to cells and of cholesterol uptake from cells and low density lipoproteins; (e) their potential as models for high-resolution structural studies. A variety of methods will be used to accomplish these aims, including recombinant DNA methods, expression in E. coli, protein purification, fluorescence, far and near UV-CD spectroscopy, lipid-binding kinetics and equilibrium approaches, chromatographic isolation of rHDL, electrophoretic analysis of protein fragmentation, cross-linking, and rHDL sizes. The functional studies will include the determination of the kinetics of the LCAT reaction in our laboratory, and a collaborative study of cell binding and cholesterol efflux from cells.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Research Project (R01)
Project #
Application #
Study Section
Metabolism Study Section (MET)
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of Illinois Urbana-Champaign
Schools of Arts and Sciences
United States
Zip Code
Arnulphi, Cristina; Sanchez, Susana A; Tricerri, M Alejandra et al. (2005) Interaction of human apolipoprotein A-I with model membranes exhibiting lipid domains. Biophys J 89:285-95
Tian, Shaomin; Choi, Won-Tak; Liu, Dongxiang et al. (2005) Distinct functional sites for human immunodeficiency virus type 1 and stromal cell-derived factor 1alpha on CXCR4 transmembrane helical domains. J Virol 79:12667-73
Choi, Won-Tak; Tian, Shaomin; Dong, Chang-Zhi et al. (2005) Unique ligand binding sites on CXCR4 probed by a chemical biology approach: implications for the design of selective human immunodeficiency virus type 1 inhibitors. J Virol 79:15398-404
Arnulphi, Cristina; Jin, Lihua; Tricerri, M Alejandra et al. (2004) Enthalpy-driven apolipoprotein A-I and lipid bilayer interaction indicating protein penetration upon lipid binding. Biochemistry 43:12258-64
Tian, Shaomin; Jonas, Ana (2002) Structural and functional properties of apolipoprotein A-I mutants containing disulfide-linked cysteines at positions 124 or 232. Biochim Biophys Acta 1599:56-64
Tricerri, M Alejandra; Sanchez, Susana A; Arnulphi, Cristina et al. (2002) Interaction of apolipoprotein A-I in three different conformations with palmitoyl oleoyl phosphatidylcholine vesicles. J Lipid Res 43:187-97
Behling Agree, Andrea K; Tricerri, M Alejandra; Arnvig McGuire, Kirsten et al. (2002) Folding and stability of the C-terminal half of apolipoprotein A-I examined with a Cys-specific fluorescence probe. Biochim Biophys Acta 1594:286-96
de Beer, M C; Durbin, D M; Cai, L et al. (2001) Apolipoprotein A-I conformation markedly influences HDL interaction with scavenger receptor BI. J Lipid Res 42:309-13
de Beer, M C; Durbin, D M; Cai, L et al. (2001) Apolipoprotein A-II modulates the binding and selective lipid uptake of reconstituted high density lipoprotein by scavenger receptor BI. J Biol Chem 276:15832-9
Tricerri, M A; Behling Agree, A K; Sanchez, S A et al. (2001) Arrangement of apolipoprotein A-I in reconstituted high-density lipoprotein disks: an alternative model based on fluorescence resonance energy transfer experiments. Biochemistry 40:5065-74

Showing the most recent 10 out of 51 publications