Origin and evolution of group XI secretory phospholipase A2 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 LusPLA2s with already characterized plant sPLA2s revealed the presence of conserved motifs and signature domains necessary to classify them as secretory phospholipase A2. Phylogenetic analysis of flax sPLA2 with representative sPLA2s 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 LusPLA2s with earlier reported plant sPLA2s, based on their gene architectures, sequence similarities, and domain structures are presented elucidating the uniqueness of flax sPLA2.