NMR Studies of Human Apolipoprotein-AI
EMSL Project ID
2428
Abstract
In this proposal, we plan to focus on determining the NMR structure of lipid-free human apoA-I(1-186). ApoA-I is a 243-residue protein (28.1 kDa), which is the main protein component of HDL, a lipoprotein particle with good cholesterol. A higher level of HDL is well-correlated with a lower risk of heart diseases. ApoAI also serves as a ligand of the HDL receptor, SR-BI, and an activator of LCAT, a key enzyme in reverse cholesterol transport. Unfortunately, there are not many structural studies reported to date for this important plasma protein. In 1997, a X-ray crystal structure of apoA-I(44-243) had been reported, however, this structure was not able to explain the structure/functional data of apoA-I. One difficulty for structural study of apoA-I is that this protein aggregates at a very low concentration. The aggregation property prevents apoAI from crystallization. Therefore, we propose to determine the structure of apoA-I using NMR techniques. Our preliminary data indicated that full-length apoA-I aggregates under NMR sample concentration (~ 1 mM), however, apoA-I(1-186) aggregates much less than full-length apoA-I (data not shown). We have worked out an NMR experimental condition in which apoA-I(1-186) is monomeric at ~1 mM concentration. Thus, we are in a good position to carry out a complete structural study of this apoAI truncation mutant using NMR techniques. We believe that this study serves as a first step towards NMR studies of full-length apoA-I. This proposal is supported by a grant from the International HDL Research Award. We anticipate that the structures of human apoA-I will help us understand how apoA-I recruits lipids to initiate HDL formation and how apoA-I promotes HDL to recruit more neutral lipids, two central roles played by apoA-I in reverse cholesterol transport. Since a low level of plasma HDL and a compromised HDL function are the common thread of metabolic disorders/diseases including: atherosclerosis, diabetes, obesity, stroke, and Alzheimer's diseases, the results obtained from this proposal should have significant implications for the intervention of new medicine to treat these metabolic disorders/diseases.
Project Details
Project type
Capability Research
Start Date
2002-04-17
End Date
2002-08-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Apolipoprotein AI tertiary structures determine stability and phospholipidbinding activity of discoidal high-density lipoprotein particles of different sizes
Bin Chen, Xuefeng Ren, Tracey Neville, Gray Jerome, David W. Hoyt, Daniel Sparks, Gang Ren, and Jianjun Wang
Received 14 November 2008; Revised 25 February 2009; Accepted 26 February 2009
DOI: 10.1002/pro.101 Published online 16 March 2009 proteinscience.org