Genomic structure, expression and functional characterization of arginine kinase (EcAK) from Exopalaemon carinicauda

Arginine kinase (AK, EC 2.7.3.3) plays an important role in cells with high, fluctuating energy requirements. In invertebrates, AK is the major phosphagen kinase that modulates the energy metabolism. Here, the full-length cDNA sequence encoding arginine kinase (EcAK) was obtained from the Exopalaemon carinicauda. The complete nucleotide sequence of EcAK contained a 1068 bp open reading frame (ORF) encoding EcAK precursor of 355 amino acids. The genomic DNA fragment of EcAK with the corresponding cDNA sequence is composed of 4 exons and 3 introns. The domain architecture of the deduced EcAK protein contained an ATP-gua_PtransN domain and an ATP-gua_Ptrans domain. EcAK mRNA was predominantly expressed in the muscle. The expression of EcAK in the prawns challenged with Vibrio parahaemolyticus and Aeromonas hydrophila changed in a time-dependent manner. Then, EcAK was recombinantly expressed in Pichia pastoris and the purified recombinant EcAK had the same enzymatic characterization as AK from the muscle of Euphausia superba. In conclusion, EcAK may play the same biological activity in E. carinicauda as those from other crustaceans.