title: Complete subunit sequences, structure and evolution of the 6 x 6-mer hemocyanin from the common house centipede, Scutigera coleoptrata.
abstract: Hemocyanins are large oligomeric copper-containing proteins that serve for the transport of oxygen in many arthropod species. While studied in detail in the Chelicerata and Crustacea, hemocyanins had long been considered unnecessary in the Myriapoda. Here we report the complete molecular structure of the hemocyanin from the common house centipede Scutigera coleoptrata (Myriapoda: Chilopoda), as deduced from 2D-gel electrophoresis, MALDI-TOF mass spectrometry, protein and cDNA sequencing, and homology modeling. This is the first myriapod hemocyanin to be fully sequenced, and allows the investigation of hemocyanin structure-function relationship and evolution. S. coleoptrata hemocyanin is a 6 x 6-mer composed of four distinct subunit types that occur in an approximate 2 : 2 : 1 : 1 ratio and are 49.5-55.5% identical. The cDNA of a fifth, highly diverged, putative hemocyanin was identified that is not included in the native 6 x 6-mer hemocyanin. Phylogenetic analyses show that myriapod hemocyanins are monophyletic, but at least three distinct subunit types evolved before the separation of the Chilopoda and Diplopoda more than 420 million years ago. In contrast to the situation in the Crustacea and Chelicerata, the substitution rates among the myriapod hemocyanin subunits are highly variable. Phylogenetic analyses do not support a common clade of Myriapoda and Hexapoda, whereas there is evidence in favor of monophyletic Mandibulata.
authors.affiliation: Institute of Zoology, Molecular Animal Physiology, University of Mainz, Germany.
authors.forename: Kristina
authors.initials: K
authors.lastname: Kusche
authors.forename: Anne
authors.initials: A
authors.lastname: Hembach
authors.forename: Silke
authors.initials: S
authors.lastname: Hagner-Holler
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Gebauer
authors.forename: Thorsten
authors.initials: T
authors.lastname: Burmester
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001181:Arthropods / Q000737:chemistry* / Q000235:genetics; D003001:Cloning, Molecular; D019143:Evolution, Molecular; D006433:Hemocyanins / Q000737:chemistry* / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010802:Phylogeny; D011487:Protein Conformation; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics; D016415:Sequence Alignment
chemical_list: D021122:Protein Subunits; D006433:Hemocyanins