Identification, characterization, and molecular phylogeny of scorpion enolase (Androctonus crassicauda and Hemiscorpius lepturus)

Scorpions are the oldest terrestrial fauna with an ancient evolutionary history. To study the origins of scorpions, we conducted a molecular phylogenetic study of the arthropod using slowly evolving enolase sequences. In this study, we used deep RNA-seq technology to identify the enolase sequences of Androctonus crassicauda and Hemiscorpius lepturus scorpions. The scorpion's enolase sequences were in silico analyzed to predict the protein structures, physicochemical characterization, and exon-intron organization. The enolase of the scorpion was found to be a protein of 433 amino acids with a molecular mass of similar to 47 kDa and an acidic isoelectric point. Here, we reported the existence of 8 exons and an inner GC/AG intron for scorpion enolase. Using homology modeling, the enolase of the scorpions was found to be very conservative during the evolution process. Furthermore, our phylogenetic analysis indicated the independent evolution of the Buthidae family from other scorpions and also the sister group relationship of Hemiscorpionidae with the Caraboctonidae families. The scorpions' enolase sequences demonstrated a close fit to those of spiders, followed by mite counterparts. This strongly supports our phylogeny analysis, which indicates a sister-group relationship between scorpions and spiders and their common ancestors with mites. This study provided support for the pairing of scorpions with spiders, mites, etc. using enolase as a nuclear gene. Our molecular clock analyzes of the arthropod show that the most recent common ancestor of arachnids and insects were diversified in the Cryogenian period of Neoproterozoic era, earlier than dates reported from fossil records.