title: Fusion and retrotransposition events in the evolution of the sea anemone Anemonia viridis neurotoxin genes.
abstract: Sea anemones are sessile predators that use a variety of toxins to paralyze prey and foe. Among these toxins, Types I, II and III are short peptides that affect voltage-gated sodium channels. Anemonia viridis is the only sea anemone species that produces both Types I and III neurotoxin. Although the two toxin types are unrelated in sequence and three-dimensional structure, cloning and comparative analysis of their loci revealed a highly similar sequence at the 5' region, which encodes a signal peptide. This similarity was likely generated by gene fusion and could be advantageous in transcript stability and intracellular trafficking and secretion. In addition, these analyses identified the processed pseudogenes of the two gene families in the genome of A. viridis, probably resulting from retrotransposition events. As presence of processed pseudogenes in the genome requires transcription in germ-line cells, we analyzed oocyte-rich ovaries and found that indeed they contain Types I and III transcripts. This result raises questions regarding the role of toxin transcripts in these tissues. Overall, the retrotransposition and gene fusion events suggest that the genes of both Types I and III neurotoxins evolved in a similar fashion and share a partial common ancestry.
authors.affiliation: Department of Plant Sciences, Tel-Aviv University, Ramat-Aviv, Israel. yehum79@yahoo.com
authors.forename: Yehu
authors.initials: Y
authors.lastname: Moran
authors.forename: Hagar
authors.initials: H
authors.lastname: Weinberger
authors.forename: Nimrod
authors.initials: N
authors.lastname: Lazarus
authors.forename: Maya
authors.initials: M
authors.lastname: Gur
authors.forename: Roy
authors.initials: R
authors.lastname: Kahn
authors.forename: Dalia
authors.initials: D
authors.lastname: Gordon
authors.forename: Michael
authors.initials: M
authors.lastname: Gurevitz
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002874:Chromosome Mapping; D021901:DNA, Intergenic / Q000235:genetics; D019143:Evolution, Molecular; D005786:Gene Expression Regulation; D050939:Gene Fusion; D008969:Molecular Sequence Data; D009498:Neurotoxins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D010802:Phylogeny; D011544:Pseudogenes / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018626:Retroelements / Q000235:genetics*; D012615:Sea Anemones / Q000235:genetics*; D017386:Sequence Homology, Amino Acid
chemical_list: D021901:DNA, Intergenic; D009498:Neurotoxins; D012333:RNA, Messenger; D018626:Retroelements