title: On the origin of protein synthesis factors: a gene duplication/fusion model.
abstract: Sequence similarity has given rise to the proposal that IF-2, EF-G, and EF-Tu are related through a common ancestor. We evaluate this proposition and whether the relationship can be extended to other factors of protein synthesis. Analysis of amino acid sequence similarity gives statistical support for an evolutionary affiliation among IF-1, IF-2, IF-3, EF-Tu, EF-Ts, and EF-G and suggests further that this association is a result of gene duplication/fusion events. In support of this mechanism, the three-dimensional structures of IF-3, EF-Tu, and EF-G display a predictable domain structure and overall conformational similarity. The model that we propose consists of three consecutives duplication/fusion events which would have taken place before the divergence of the three superkingdoms: eubacteria, archaea, and eukaryotes. The root of this protein superfamily tree would be an ancestor of the modern IF-1 gene sequence. The repeated fundamental motif of this protein superfamily is a small RNA binding domain composed of two alpha-helices packed along side of an antiparallel beta-sheet.
authors.affiliation: Département de biochimie, Université de Montréal, Québec, Canada.
authors.forename: B
authors.initials: B
authors.lastname: Cousineau
authors.forename: F
authors.initials: F
authors.lastname: Leclerc
authors.forename: R
authors.initials: R
authors.lastname: Cedergren
mesh_terms: D000595:Amino Acid Sequence; D019677:Artificial Gene Fusion; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics*; D019143:Evolution, Molecular; D008958:Models, Molecular; D008969:Molecular Sequence Data; D005810:Multigene Family; D020653:Peptide Elongation Factor G; D010444:Peptide Elongation Factor Tu / Q000737:chemistry / Q000235:genetics; D010445:Peptide Elongation Factors / Q000737:chemistry / Q000235:genetics*; D010448:Peptide Initiation Factors / Q000737:chemistry / Q000235:genetics; D039665:Prokaryotic Initiation Factor-3; D017434:Protein Structure, Tertiary; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000235:genetics; D016415:Sequence Alignment
chemical_list: D001426:Bacterial Proteins; D020653:Peptide Elongation Factor G; D010445:Peptide Elongation Factors; D010448:Peptide Initiation Factors; D039665:Prokaryotic Initiation Factor-3; D016601:RNA-Binding Proteins; C023512:elongation factor Ts; D010444:Peptide Elongation Factor Tu