Structural Studies of Lipid-free Apolipoprotein A-I
EMSL Project ID
10594
Abstract
Apolipoprotein A-I (apoAI) is a 243-residue exchangeable apolipoprotein that plays a key role in clearing the "bad cholesterol" from the human blood stream (reverse cholesterol transport. ApoAI is the most abundant protein component in high-density lipoprotein (HDL, ~70%). Depending on the extent of lipidation, apoAI displays a dramatic conformational plasticity and may adopt one of four distinct conformations, including: (1). Lipid-free apoAI conformation (for specific phospholipid-binding, M.W.: 28 kDa). (2). ApoAI on preb-HDL (for specific cholesterol-binding, M.W.: ~55 kDa). (3). ApoAI on discoidal HDL (for specific LCAT activation, M.W.: ~140-160 kDa). (4). ApoAI on spherical HDL (for specific HDL-receptor binding, M.W.: 12-180 kDa). We plan to solve lipid-free apoAI conformation. In order to achieve this goal, we prepared a monomeric mouse apoAI(1-216), solved aggregation problem in structural studies of apoAI. ApoAI(1-216) contains most of the regions that are responsible for its activity, and the C-terminal 24-residues are unstructured in the lipid-free state, the NMR structure of apoAI(1-216) should represent the structure of lipid-free apoAI. In this proposal, we request a 600MHz (with a cold probe) time for one week, and a 800MHz time for one week. The 600MHz NMR time is for the measurement of 3D CCC-TOCSY-NNH and HCC-TOCSY-NNH. The 800 MHz NMR time is for 3D 15N-edited NOESY with both perdeuterated and 30% deuterated triple-labeled apoAI(1-216) samples. We are currently collecting 3D triple-resonance NMR spectra. With these NMR data, we will be able to carry out a complete NMR spectral assignment of this protein, which is the first step towards the structural determination of lipid-free apoAI.
Project Details
Project type
Capability Research
Start Date
2004-10-20
End Date
2005-12-12
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
A complete NMR spectral assignment of the lipid-free mouse apolipoprotein A-I (apoAI) C-terminal truncation mutant, apoAI(1-216) Biomol NMR Assign (2007) 1:109–111 DOI 10.1007/s12104-007-9031-2
Chen B, X Ren, T Neville, WG Jerome, DW Hoyt, DL Sparks, G Ren, and J Wang. 2009. "Apolipoprotein AI tertiary structures determine stability and phospholipid-binding activity of discoidal high-density lipoprotein particles of different sizes." Protein Science 18(5):921-935. doi:10.1002/pro.101