Dr. Oda, Associate Staff Scientist, has been at CHORI since 2000. He arrives here from Lawrence Berkeley National Laboratory, where he examined the biochemical nature and physiological role of high density lipoprotein (HDL) associated enzymes and proteins. As a member of the Lipid Biology in Health & Disease research group he is continuing his work on HDL focusing on exchangeable apolipoprotein structure-function.
Exchangeable apolipoproteins are key mediators of lipid metabolism and homeostasis, a central aspect of whole body physiology. They facilitate this essential metabolic function by transporting lipids between peripheral tissues and the liver/intestines. The ability of exchangeable apolipoproteins to maintain their solubility in both aqueous and lipid environments is essential to the sequestration and deposition of lipids. This unique and definitive property is attributed to the conformational adaptability of exchangeable apolipoproteins, which allows them to modulate their structure in response to their environment.
Apolipoprotein A-I (apoA-I) is a prominent member of the exchangeable apolipoprotein class of proteins and the primary focus of Dr. Odas work. It is the principal protein component of HDL and is a primary determinant of HDL structure, composition, and stability. The plasma level of apoA-I is inversely correlated with the incidence of atherosclerosis and is one of the single best parameters for assessing the risk for the onset of this disease. This correlation is primarily attributed to apoA-Is central role in lipid metabolism and cholesterol homeostasis, as a principal facilitator of reverse cholesterol transport (RCT), a process wherein cholesterol and phospholipid are mobilized from peripheral tissues and delivered to the liver and steroidogenic organs. HDL derives a large portion of its functionality from apoA-Is ability to sequester phospholipid and cholesterol and to functionally interact with plasma enzymes and cellular receptors. During RCT, HDLs interaction with enzymes and cellular receptors must occur in an ordered fashion appropriate to the HDL particles lipid composition.
Dr. Odas program is focused on examining apoA-Is structural features that allow it to facilitate HDL function. In particular, he is examining the structural adaptation apoA-I makes as it partitions into a lipid environment, a key event in lipid transport. He has also begun studies into the molecular properties governing the association of HDL specific enzymes and receptors with apoA-I and ultimately HDL.
One of the most representative examples of the research of Dr. Odas program is reported in the June 2003 issue of the journal Nature Structural Biology in an article entitled The C-terminal domain of apolipoprotein A-I contains a lipid-sensitive conformational trigger. The findings reported in this article describe the effect of lipid association on apoA-I conformation and are the culmination of four years of effort to develop methodologies for the examination of the precise structural nature of apoA-I and other exchangeable apolipoproteins. Dr. Oda is currently furthering these finding by examining the conformational changes throughout the entire apoA-I molecule, increasing the resolution of the data and identify regulatory mechanisms controlling this conformational adaptation.