The long standing objectives of my research are to provide the detailed structural and dynamic description of the plasma lipoproteins and apolipoproteins that is crucial to understanding the molecular mechanisms of such physiological processes as lipoprotein formation, receptor interactions, lipoprotein inter-conversions, and apoprotein exchange together with the changes in these characteristics that underlie the pathophysiology of atherosclerosis. Our research has been a component of a Program Project since its inception in 1980 and I have led the Program since 2001, taking over from Dr. Small. Building on initial training in diffraction methods and biophysics, I have maintained and expanded my expertise in state-of-the-art methods of molecular biophysics and structural biology including crystallography, electron microscopy/image processing, calorimetry and thermodynamics, circular dichroism, and molecular modeling/mechanics to probe the structure-function relationships of the lipoproteins and apolipoproteins. This includes a one year sabbatical at the MRC Laboratory of Molecular Biology, Cambridge, England developing electron microscopy.
My long standing research program has involved many collaborations with current and past Program Project investigators, particularly Drs. Gursky, Small, and McKnight. Our previous work over more than three decades has focused on the structural and thermodynamic properties of specific lipoproteins (HDL and LDL), and apolipoproteins, particularly apoA-1, together with studies of the LDL receptor. We derived the first structural description of HDL, nascent HDL and LDL using x-ray methods. Our mutation studies of the conformation, stability, and lipid binding properties have contributed to providing a framework for understanding the molecular properties of apoA-1. Furthermore, our studies of peptides representing segments of apoA-1, together with “idealized” sequence models, have provided information on the role of specific residues and domains, and their interactions in the structure and stability of apoA-1. For LDL, we pioneered the use of cryo-electron microscopy to study LDL structure and used mAb labeling to investigate the topology of apoB. In collaborations with Dr. Graham Shipley, a long standing collaborator and colleague, our approach for the LDL receptor has focused on structural studies of the functional extracellular domain of the receptor reconstituted into lipid vesicles.