Heterologous expression of lipoprotein-associated phospholipase A2 in different expression systems

Lipoprotein-associated phospholipase A2 (Lp-PLA2) is a key enzyme involved in atherosclerosis, and has been considered as a new target for drug discovery. The major difficulty for high-throughput screening of Lp-PLA2 inhibitors and for functional studies was their fast and efficient production. Purification of native Lp-PLA2 from human plasma was complicated and produced a very low yield. We herein examined the feasibility of expressing and purifying recombinant Lp-PLA2 in different heterologous expression systems. The fusion Lp-PLA2 was expressed at high levels and exhibited strong enzyme activity in insect cell-baculovirus expression system. The functional enzyme could also be produced in Pichia pastoris. The inclusion of a Kozak sequence increased greatly the expression level of recombinant Lp-PLA2 in insect cells, but had little effect on the expression of recombinant Lp-PLA2 in P. pastoris and Escherichia coli. P. pastoris-produced Lp-PLA2 could be purified rapidly and conveniently through a one-step procedure, while baculovirus-produced Lp-PLA2 could be efficiently purified through a two-step procedure. This ability to readily produce recombinant Lp-PLA2 could provide a screening model for Lp-PLA2 inhibitors and will facilitate further studies on this enzyme.