Meeting Abstract
Peroxiredoxins (Prx) are proteins found in all domains of life, and help to mediate the oxidative stress response by binding and neutralizing reactive oxygen species (ROS). To gain insight into Prx evolution and diversification, we first identified Prx sequences in the cnidarian sea anemone Nematostella vectensis. We classified these sequences both through construction of a maximum likelihood-based phylogeny and through queries of the PREX Database, which enables subfamily assignment based on structurally relevant motifs. In this way, we identified four bona-fide Prx proteins in N. vectensis: Prx4a, Prx4b, Prx5 and Prx6. In contrast to many bilaterians, N. vectensis is missing clear homologues to Prx1-3 family members. Like other members of the same subfamilies, Prx4a, Prx4b and Prx 5 contain a catalytic cysteine and a resolving cysteine, while Prx6 contains only the catalytic cysteine. The two Prx4 genes appear to have resulted from a duplication event deep within the cnidarian lineage. Both N. vectensis Prx4 genes also contain a deeply conserved cysteine residue that has been shown to undergo circadian cycles of hyperoxidation in diverse organisms. We find potential evidence for subfunctionalization of these two genes in that only Prx4a contains a predicted signal peptide at the amino terminus. Finally, we measured Prx mRNA expression following exposure to elevated temperature, low salinity and hydrogen peroxide, conditions that have been reported to induce Prx genes in a variety of animals. Surprisingly, we did not detect robust upregulation of Prx expression with any of these treatments. This may reflect the high abundance and stability of Prx proteins and their ability to be recycled and reused.
