title: Invertebrate data predict an early emergence of vertebrate fibrillar collagen clades and an anti-incest model.
abstract: Fibrillar collagens are involved in the formation of striated fibrils and are present from the first multicellular animals, sponges, to humans. Recently, a new evolutionary model for fibrillar collagens has been suggested (Boot-Handford, R. P., Tuckwell, D. S., Plumb, D. A., Farrington Rock, C., and Poulsom, R. (2003) J. Biol. Chem. 278, 31067-31077). In this model, a rare genomic event leads to the formation of the founder vertebrate fibrillar collagen gene prior to the early vertebrate genome duplications and the radiation of the vertebrate fibrillar collagen clades (A, B, and C). Here, we present the modular structure of the fibrillar collagen chains present in different invertebrates from the protostome Anopheles gambiae to the chordate Ciona intestinalis. From their modular structure and the use of a triple helix instead of C-propeptide sequences in phylogenetic analyses, we were able to show that the divergence of A and B clades arose early during evolution because alpha chains related to these clades are present in protostomes. Moreover, the event leading to the divergence of B and C clades from a founder gene arose before the appearance of vertebrates; altogether these data contradict the Boot-Handford model. Moreover, they indicate that all the key steps required for the formation of fibrils of variable structure and functionality arose step by step during invertebrate evolution.
authors.affiliation: Institut de Biologie et Chimie des Protéines, CNRS, Unité Mixte de Recherche 5086, Institut Fédératif de Recherche 128 BioSciences Lyon-Gerland, Université Claude Bernard-Lyon 1, 7 Passage du Vercors, 69367 Lyon Cedex 07, France.
authors.forename: Abdel
authors.initials: A
authors.lastname: Aouacheria
authors.forename: Caroline
authors.initials: C
authors.lastname: Cluzel
authors.forename: Claire
authors.initials: C
authors.lastname: Lethias
authors.forename: Manolo
authors.initials: M
authors.lastname: Gouy
authors.forename: Robert
authors.initials: R
authors.lastname: Garrone
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Exposito
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000852:Anopheles / Q000737:chemistry / Q000235:genetics; D002938:Ciona intestinalis / Q000737:chemistry / Q000235:genetics; D019143:Evolution, Molecular; D005091:Exons; D024022:Fibrillar Collagens / Q000737:chemistry / Q000145:classification* / Q000235:genetics*; D020440:Gene Duplication; D006801:Humans; D007438:Introns; D007448:Invertebrates / Q000737:chemistry / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny; D016415:Sequence Alignment; D014714:Vertebrates / Q000235:genetics* / Q000378:metabolism
chemical_list: D024022:Fibrillar Collagens