Phospholipases A2 in the genome of the sea anemone Nematostella vectensis

The genome of the sea anemone Nematostella vectensis (Nv) (Cnidaria, Anthozoa) was sequenced recently (Putnam et al., Science 317: 86, 2007). In the current study, 22 proteins of Nv were identified as putative phospholipases A2 (PLA2) that showed up to 40–50% sequence identity with secreted or intracellular PLA2s including those of humans. Nv1–Nv6 PLA2s have identity with secreted human group (G)IB and GIIA PLA2s and PLA2s of the sea anemones Adamsia carciniopados and Urticina crassicornis. Nv7 and Nv8 PLA2s have identity with human and bee venom GIII PLA2s and Nv9 PLA2 with GXIIA PLA2. Nv10–Nv13 PLA2s show identity with GIX PLA2 of Conus magus and bacterial PLA2s but no significant identity with any human PLA2. Nv14 has identity with intracellular GIV PLA2, Nv15 with GVII PLA2, Nv16 and Nv17 with GVIII PLA2, Nv18–Nv20 with GVI PLA2, and Nv21 and Nv22 with patatin, respectively. The observations indicate that the cnidarian phospholipasome contains a rich array of orthologs of most types of animal PLA2s, and that many of the PLA2-driven vital functions prevail in these ancient metazoans. Cnidarian PLA2s may be considered as evolutionary precursors of PLA2s of higher animals.