Conserved domains and evolution of secreted phospholipases A2

Secreted phospholipases A2 (sPLA2s) are lipolytic enzymes present in organisms ranging from prokaryotes to eukaryotes but their origin and emergence are poorly understood. We identified and compared the conserved domains of 333 sPLA2s and proposed a model for their evolution. The conserved domains were grouped into seven categories according to the in silico annotated conserved domain collections of ‘cd00618: PLA2_like’ and ‘pfam00068: Phospholip_A2_1’. PLA2s containing the conserved domain cd04706 (plant‐specific PLA2) are present in bacteria and plants. Metazoan PLA2s of the group (G) I/II/V/X PLA2 collection exclusively contain the conserved domain cd00125. GIII PLA2s of both vertebrates and invertebrates contain the conserved domain cd04704 (bee venom‐like PLA2), and mammalian GIII PLA2s also contain the conserved domain cd04705 (similar to human GIII PLA2). The sPLA2s of bacteria, fungi and marine invertebrates contain the conserved domain pfam09056 (prokaryotic PLA2) that is the only conserved domain identified in fungal sPLA2s. Pfam06951 (GXII PLA2) is present in bacteria and is widely distributed in eukaryotes. All conserved domains were present across mammalian sPLA2s, with the exception of cd04706 and pfam09056. Notably, no sPLA2s were found in Archaea. Phylogenetic analysis of sPLA2 conserved domains reveals that two main clades, the cd‐ and the pfam‐collection, exist, and that they have evolved via gene‐duplication and gene‐deletion events. These observations are consistent with the hypothesis that sPLA2s in eukaryotes shared common origins with two types of bacterial sPLA2s, and their persistence during evolution may be related to their role in phospholipid metabolism, which is fundamental for survival. Phylogenetic analysis of the conserved domains of secreted phospholipases A2 (sPLA2s) revealed that two main clades, the cd‐ and the pfam‐collection have evolved via gene duplication and deletion events. The observations indicate that sPLA2s in eukaryotes shared common origins with two types of bacterial sPLA2s and their persistence during evolution may be related to their role in phospholipid metabolism which is fundamental for survival.