Interaction of LCAT enzyme with lipid surfaces and apolipoprotein A-I derived peptides

The lecithin cholesterol acyltransferase (LCAT) enzyme catalyses the formation of cholesteryl esters which is detrimental for the formation of mature spherical high density particles (HDL) which in turn play a crucial role in the reverse cholesterol transport (RCT). Given the importance of efficient RCT in decreasing the development of coronary heart disease (CHD), it would be beneficial to understand how LCAT and apolipoprotein A-I (apoA-I), the superior activator of LCAT, are mediating the enzymatic reaction in unison at the atomistic level. Here, we have studied how LCAT interacts with a lipid bilayer and apoA-I derived amphiphilic peptides through atomistic molecular dynamics simulations and surface sensitive biophysical methods. We show that LCAT attaches on the lipid bilayer surfaces through a hydrophobic patch located at the previously suggested membrane interacting region, but also through the lid region of LCAT. Further, we demonstrate how phospholipids and cholesterol enter the active site of LCAT and how apoAI may facilitate this. The results presented here could prove to be valuable in the designing of novel molecular therapies for LCAT deficiencies and CHD