Structural Determination of ApoLp-III/HDL Particles
EMSL Project ID
2607
Abstract
This research proposal is focused on determining the NMR structure of an exchangeable apolipoprotein, apolipophorin-III,that is associated with high-density lipoprotein (HDL).This is an important,unsolved biological question since HDL particles play critical roles in clearance of excess cholesterol in peripheral tissue,thus preventing atherosclerosis.Thus,this project is directly related to human diseases.We have solved the NMR structures of two lipid-free full-length apoLp-IIIs,M.sexta apoLp-III (166-residues,Wang et al,1997,2002)and L.migratoria apoLp-III (164-residues,Fan et al,2001,Fan et al,2002).Our hypothesis is that upon lipid-binding,the lipid-free apoLp-III helix-bundle opens at hinges at one end of the molecule, adopting an extended á -helical structure that exposes hydrophobic surfaces for lipid-binding.Previous experimental evidence strongly supports this hypothesis.However,a final confirmation of this hypothesis requires a lipid-bound structure of apoLp-III and currently we do NOT have such a structure available.A structural study of apoLp-III/HDL using x-ray crystallography is impossible,since it resists crystallization.We have collected significant preliminary data for this project,allowing us to demonstrate the feasibility of this difficult project.Our immediate goal is to develop this project for NIH/NSF funding.However,we feel that we will have better position for NIH funding if we can collect more preliminary data that we propose to collect in this PNNL proposal.Since the lipid-bound apoLp-III gives particle sizes of 43.3 kDa (for apoLp-III/DPC)and 61.1 kDa (for apoLp-III/Pre â -HDL),a high-field NMR instrument is critical for this project and we do not have such an instrument in our institution.
Project Details
Project type
Capability Research
Start Date
2002-10-01
End Date
2003-07-23
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members