Characterization of hemocyanin from the peacock mantis shrimp Odontodactylus scyllarus (Malacostraca:Hoplocarida)
Hemocyanin is the blue respiratory protein of many arthropod species. While its structure, evolution, and physiological function have been studied in detail in Decapoda, there is little information on hemocyanins from other crustacean taxa. Here, we have investigated the hemocyanin of the peacock mantis shrimp Odontodactylus scyllarus, which belongs to the Stomatopoda (Hoplocarida). O. scyllarus hemocyanin forms a dodecamer (2 × 6-mer), which is composed of at least four distinct subunit types. We obtained the full-length cDNA sequences of three hemocyanin subunits, while a fourth cDNA was incomplete at its 5′ end. The complete full-length cDNAs of O. scyllarus hemocyanin translate into polypeptides of 650–662 amino acids, which include signal peptides of 16 or 17 amino acids. The predicted molecular masses of 73.1–75.1 kDa correspond well with the main hemolymph proteins detected by SDS-PAGE and Western blotting using various anti-hemocyanin antibodies. Phylogenetic analyses show that O. scyllarus hemocyanins belong to the β-type of malacostracan hemocyanin subunits, which diverged from the other subunits before the radiation of the malacostracan subclasses around 520 million years ago. Molecular clock analysis revealed an ancient and complex pattern of hemocyanin subunit evolution in Malacostraca and also allowed dating divergence times of malacostracan taxa.