Novel Metagenome-Derived, Cold-Adapted Alkaline Phospholipase with Superior Lipase Activity as an Intermediate between Phospholipase and Lipase

A novel lipolytic enzyme was isolated from a metagenomic library obtained from tidal flat sediments on the Korean west coast. Its putative functional domain, designated MPlaG, showed the highest similarity to phospholipase A from Grimontia hollisae CIP 101886, though it was screened from an emulsified tricaprylin plate. Phylogenetic analysis showed that MPlaG is far from family 1.6 lipases, including Staphylococcus hyicus lipase, a unique lipase which can hydrolyze phospholipids, and is more evolutionarily related to the bacterial phospholipase A, family. The specific activities of MPlaG against olive oil and phosphatidylcholine were determined to be 2,957 +/- 144 and 1,735 +/- 147 U mg(-1), respectively, which means that MPlaG is a lipid-preferred phospholipase. Among different synthetic esters, triglycerides, and phosphatidylcholine, purified MPlaG exhibited the highest activity toward p-nitrophenyl palmitate (C-16), tributyrin (C-4), and 1,2-dihexanoyl-phosphatidylcholine (C-8). Finally, MPlaG was identified as a phospholipase A(1) with lipase activity by cleavage of the sn-1 position of OPPC, interfacial activity, and triolein hydrolysis. These findings suggest that MPlaG is the first experimentally characterized phospholipase A(1) with lipase activity obtained from a metagenomic library. Our study provides an opportunity to improve our insight into the evolution of lipases and phospholipases.