In silico analysis of arginine and creatine kinases, exploring the coexistence of phosphagens in the cannonball jellyfish Stomolophus sp.2

The cannonball jellyfish Stomolophus sp.2 is distributed in the southern region of the Gulf of California. At high temperatures, it shows metabolic responses that produce large amounts of adenosine triphosphate (ATP) to cope with thermal stress. In addition to mitochondria, phosphagens are suggested as one mechanism for rapid ATP production in this species. Recently, two transcripts encoding the phosphagen-kinase homologs, arginine kinase (AK) and creatine kinase (CK), were confirmed in the jellyfish transcriptome as part of the species' ability to synthesize ATP. This study identifies and characterizes both enzymes to understand the molecular adaptations of Stomolophus sp.2 to environmental challenges, and explores the evolution of this family of enzymes in the animal kingdom. The transcripts and deduced proteins from jellyfish AK and CK were analyzed and confirmed through bioinformatic analysis. Conserved domains in both proteins and their predicted structures confirmed their identity. Phylogenetic trees were built to explore these proteins' evolutionary origin in early animal history. Results revealed that the AK and CK sequences of jellyfish share conserved phosphagen-kinase signatures, N- and C-terminal domains, and a specific active site. Phylogeny suggests a divergence event in later clades, emphasizing the conservation and evolution of these enzymes. This study provides new evidence on the presence of the two phosphagen enzymes in the jellyfish; these findings expand our understanding of the evolution and molecular adaptation of phosphagen enzymes in the animal kingdom, highlighting the biological plasticity of Stomolophus sp.2 to face climate change.