279^Val→Phe Polymorphism of lipoprotein-associated phospholipase A₂ resulted in changes of folding kinetics and recognition to substrate

Introduction PLA2G7 encodes Lp-PLA₂ having role in the formation of atherosclerotic plaques by catalyzing its substrate, phosphatydilcholine (PC), to be pro-inflammatory substances. The increased risk for coronary artery disease (CAD) in Asian population has been related with this enzyme. 279^Val→Phe variant was reported to have a protective role against CAD due to, in part, secretion defect or loss of enzymatic function. Therefore, We study folding kinetics and enzyme-substrate interaction in 279^Val→Phe by using clinical and computational biology approach. Methods Polymorphisms were detected by genotyping among 103 acute myocardial infarction patients and 37 controls. Folding Lp-PLA₂ was simulated using GROMACS software by assessing helicity, hydrogen bond formation and stability. The interactions of Lp-PLA₂ and its substrate were simulated using Pyrx software followed by molecular dynamics simulation using YASARA software. Result Polymorphism of 279^Val→Phe was represented by the change of nucleotide from G to T of 994th PLA2G7 gene. The folding simulation suggested a decreased percentage of α-helix, hydrogen bond formation, hydrogen bond stability and hydrophobicity in 279^Val→Phe. The PC did not interact with active site of 279^Val→Phe as paradoxically observed in 279 valine. 279^Val→Phe polymorphism is likely to cause unstable binding to the substrate and decrease the enzymatic activity as observed in molecular dynamics simulations. The results of our computational biology study supported a protected effect of 279^Val→Phe Polymorphism showed by the odd ratio for MI of 0.22 (CI 95% 0.035-1.37) in this study. Conclusion 279^Val→Phe Polymorphism of Lp-PLA₂ may lead to decrease the enzymatic activity via changes of folding kinetics and recognition to its substrate.