title: Flatworms have lost the right open reading frame kinase 3 gene during evolution.
abstract: All multicellular organisms studied to date have three right open reading frame kinase genes (designated riok-1, riok-2 and riok-3). Current evidence indicates that riok-1 and riok-2 have essential roles in ribosome biosynthesis, and that the riok-3 gene assists this process. In the present study, we conducted a detailed bioinformatic analysis of the riok gene family in 25 parasitic flatworms (platyhelminths) for which extensive genomic and transcriptomic data sets are available. We found that none of the flatworms studied have a riok-3 gene, which is unprecedented for multicellular organisms. We propose that, unlike in other eukaryotes, the loss of RIOK-3 from flatworms does not result in an evolutionary disadvantage due to the unique biology and physiology of this phylum. We show that the loss of RIOK-3 coincides with a loss of particular proteins associated with essential cellular pathways linked to cell growth and apoptosis. These findings indicate multiple, key regulatory functions of RIOK-3 in other metazoan species. Taking advantage of a known partial crystal structure of human RIOK-1, molecular modelling revealed variability in nucleotide binding sites between flatworm and human RIOK proteins.
authors.affiliation: Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Bert
authors.initials: B
authors.lastname: Breugelmans
authors.affiliation: Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Brendan R E
authors.initials: BR
authors.lastname: Ansell
authors.affiliation: Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Neil D
authors.initials: ND
authors.lastname: Young
authors.affiliation: Structural Chemistry Program, Eskitis Institute, Griffith University, Brisbane, Australia.
authors.forename: Parisa
authors.initials: P
authors.lastname: Amani
authors.affiliation: Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Andreas J
authors.initials: AJ
authors.lastname: Stroehlein
authors.affiliation: HHMI, Division of Biology, California Institute of Technology, Pasadena, California, USA.
authors.forename: Paul W
authors.initials: PW
authors.lastname: Sternberg
authors.affiliation: Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Aaron R
authors.initials: AR
authors.lastname: Jex
authors.affiliation: Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria, Australia.
authors.forename: Peter R
authors.initials: PR
authors.lastname: Boag
authors.affiliation: 1] Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, Australia [2] Structural Chemistry Program, Eskitis Institute, Griffith University, Brisbane, Australia.
authors.forename: Andreas
authors.initials: A
authors.lastname: Hofmann
authors.affiliation: Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Robin B
authors.initials: RB
authors.lastname: Gasser
mesh_terms: D000818:Animals; D005075:Biological Evolution; D019143:Evolution, Molecular; D016366:Open Reading Frames / Q000235:genetics*; D010986:Platyhelminths / Q000235:genetics*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics*
chemical_list: D017346:Protein Serine-Threonine Kinases