Mechanistic Insights into the Activation of Lecithin-Cholesterol Acyltransferase in Therapeutic Nanodiscs Composed of Apolipoprotein A-I Mimetic Peptides and Phospholipids

Other conference contribution, 2023

Lecithin-cholesterol acyltransferase (LCAT) maturates high density lipoprotein (HDL) particles enabling reverse cholesterol transport (RCT). Its primary cofactor on HDL is apolipoprotein A1 (apoA1). In order to boost RCT efficiency to combat atherosclerotic cardiovascular diseases, apoA1 mimetic peptides have been developed, such as 22 amino acid long 22A. Despite being ~10 % the size of apoA1, when 22A is formulated to a synthetic HDL particle, called a nanodisc, it is able to activate LCAT as well as apoA1 based HDL. However, the mechanism of how 22A, or apoA1, activates LCAT is not known. We set out to explain this mechanism with a combination of coarse-grained molecular dynamics simulations, LCAT activity assays and electron microscopy (EM). The computational data matched the experimental data in two ways. First, EM imaging showed that LCAT binds to the perimeter of 22A based nanodiscs, which was replicated by the simulations. The overall binding pose was also consistent. Second, by simulating and assaying a set of 22A mutants, we were able to see a correlation between the in silico binding kinetics of a peptide to aspecific site in LCAT and how well the peptide activates LCAT in vitro. Taken together, we’ve shown that these simulated systems can be exploited for designing peptides with increased efficacy. A more detailed description is found in our similarly titled article in Mol. Pharmaceutics 19: 4135 -4148, 2022.