title: Polyubiquitin insertions and the phylogeny of Cercozoa and Rhizaria.
abstract: A single or double amino acid insertion at the monomer-monomer junction of the universal eukaryotic protein polyubiquitin is unique to Cercozoa and Foraminifera, closely related 'core' phyla in the protozoan infrakingdom Rhizaria. We screened 11 other candidate rhizarians for this insertion: Radiozoa (polycystine and acantharean radiolaria), a 'microheliozoan', and Apusozoa; all lack it, supporting suggestions that Foraminifera are more closely related to Cercozoa than either is to other eukaryotes. The insertion's size was ascertained for 12 additional Cercozoa to help resolve their basal branching order. The earliest branching Cercozoa generally have a single amino acid insertion, like all Foraminifera, but a large derived clade consisting of all Monadofilosa except Metopion, Helk-esimastix, and Cercobodo agilis has two amino acids, suggesting one doubling event and no reversions to a single amino acid. Metromonas and Sainouron, cercozoans of uncertain position, have a double insertion, suggesting that they belong in Monadofilosa. An alternative interpretation, suggested by the higher positions for Metopion and Cercobodo on Bayesian trees compared with most distance trees, cannot be ruled out, i.e. that the second insertion took place earlier, in the ancestral filosan, and was followed by three independent reversions to a single amino acid in Chlorarachnea, Metopion and Cercobodo.
authors.affiliation: Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK. david.bass@zoo.ox.ac.uk
authors.forename: David
authors.initials: D
authors.lastname: Bass
authors.forename: David
authors.initials: D
authors.lastname: Moreira
authors.forename: Purificación
authors.initials: P
authors.lastname: López-García
authors.forename: Stephane
authors.initials: S
authors.lastname: Polet
authors.forename: Ema E
authors.initials: EE
authors.lastname: Chao
authors.forename: Sophie
authors.initials: S
authors.lastname: von der Heyden
authors.forename: Jan
authors.initials: J
authors.lastname: Pawlowski
authors.forename: Thomas
authors.initials: T
authors.lastname: Cavalier-Smith
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000235:genetics; D000818:Animals; D001483:Base Sequence; D016054:DNA, Protozoan / Q000737:chemistry; D004275:DNA, Ribosomal / Q000737:chemistry; D056890:Eukaryota / Q000145:classification* / Q000235:genetics*; D019143:Evolution, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D010802:Phylogeny; D025821:Polyubiquitin / Q000737:chemistry / Q000235:genetics*; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics*; D012337:RNA, Ribosomal, 18S / Q000235:genetics
chemical_list: D000596:Amino Acids; D016054:DNA, Protozoan; D004275:DNA, Ribosomal; D015800:Protozoan Proteins; D012337:RNA, Ribosomal, 18S; D025821:Polyubiquitin