Biochemical and molecular characterisation of hemocyanin from the amphipod Gammarus roeseli: complex pattern of hemocyanin subunit evolution in Crustacea.
Hemocyanin is a copper-containing respiratory protein that is widespread within the arthropod phylum. Among the Crustacea, hemocyanins are apparently restricted to the Malacostraca. While well-studied in Decapoda, no hemocyanin sequence has been known from the 'lower' Malacostraca. The hemocyanin of the amphipod Gammarus roeseli is a hexamer that consists of at least five distinct subunits. The complete cDNA sequence of one subunit and a tentative partial sequence of another subunit have been determined. The complete G. roeseli hemocyanin subunit comprises 2,150 bp, which translates in a protein of 672 amino acids with a molecular mass of 76.3 kDa. Phylogenetic analyses show that, in contrast to previous assumptions, the amphipod hemocyanins do not belong to the alpha-type of crustacean hemocyanin subunits. Rather, amphipod hemocyanins split from the clade leading to alpha and gamma-subunits most likely at the time of separation of peracarid and eucarid Crustacea about 300 million years ago. Molecular clock analyses further suggest that the divergence of beta-type subunits and other crustacean hemocyanins occurred around 315 million years ago (MYA) in the malacostracan stemline, while alpha- and gamma-type subunits separated 258 MYA, and pseudohemocyanins and gamma-subunits 210 million years ago.
Hagner-Holler
Silke
S
Institute of Zoology, University of Mainz, Müllerweg 6, 55099 Mainz, Germany. burmeste@uni-mainz.de
Kusche
Kristina
K
Hembach
Anne
A
Burmester
Thorsten
T
D000595:Amino Acid Sequence / Q000235:genetics; D033304:Amphipoda / Q000235:genetics*; D000818:Animals; D001483:Base Sequence; D001499:Bayes Theorem; D017124:Conserved Sequence / Q000235:genetics; D003445:Crustacea / Q000235:genetics*; D018076:DNA, Complementary / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D019143:Evolution, Molecular; D006433:Hemocyanins / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism / Q000648:ultrastructure; D006458:Hemolymph; D006639:Histidine / Q000737:chemistry; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010802:Phylogeny; D020033:Protein Isoforms / Q000235:genetics; D021382:Protein Sorting Signals; D021122:Protein Subunits / Q000737:chemistry*; D017386:Sequence Homology, Amino Acid
D018076:DNA, Complementary; D020033:Protein Isoforms; D021382:Protein Sorting Signals; D021122:Protein Subunits; D006639:Histidine; D006433:Hemocyanins