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Researchers identify, describe structure of HDL
Huang R. Nat Struct Mol Biol. 2011;doi:10.1038/nsmb.2028.
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Findings from a new study have revealed the structure of human plasma-derived HDL and its most abundant protein, apolipoprotein A-I, which may help explain its cardioprotective effect.
“We have provided the most comprehensive set of distance constraints for native human plasma HDL particles achieved to date,” the researchers wrote. “The results unambiguously show that [apolipoprotein A-I] contacts found in model reconstituted particles occur in authentic human plasma HDL particles.”
To determine its structural framework, the researchers first divided normal human HDL into five density subfractions while further isolating those that contained predominantly apolipoprotein A-I (ApoA-I).
After using mass spectrometry and cross-linking chemistry, they found that ApoA-I in humans adopts a common general structural organization that closely resembles ApoA-I in synthetic HDL. The models, which the researchers said utilize established structures for synthetic HDL and are the first detailed models of authentic human plasma HDL, show that ApoA-I forms a cage-like structure, and that the twisting motion of the resident ApoA-I molecules modulates HDL particle size.
In a press release, W. Sean Davidson, PhD, one of the study’s investigators, said the surface of HDL, which was found to be dominated by ApoA-I, leaves little room for other proteins to bind to the surface and thus may explain the cardioprotective role of HDL.
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