Origin and evolution of group XI secretory phospholipase A 2 from flax (Linum usitatissimum) based on phylogenetic analysis of conserved domains.

Phospholipase A2 (PLA2 ) belongs to class of lipolytic enzymes (EC 3.1.1.4). Lysophosphatidic acid (LPA) and free fatty acids (FFAs) are the products of PLA2 catalyzed hydrolysis of phosphoglycerides at sn-2 position. LPA and FFA that act as second mediators involved in the development and maturation of plants and animals. Mining of flax genome identified two phospholipase A2 encoding genes, viz., LusPLA 2 I and LusPLA 2 II (Linum usitatissimum secretory phospholipase A2 ). Molecular simulation of LusPLA2 s with already characterized plant sPLA2 s revealed the presence of conserved motifs and signature domains necessary to classify them as secretory phospholipase A2 . Phylogenetic analysis of flax sPLA2 with representative sPLA2 s from other organisms revealed that they evolved rapidly via gene duplication/deletion events and shares a common ancestor. Our study is the first report of detailed phylogenetic analysis for secretory phospholipase A2 in flax. Comparative genomic analysis of two LusPLA2 s with earlier reported plant sPLA2 s, based on their gene architectures, sequence similarities, and domain structures are presented elucidating the uniqueness of flax sPLA2 .