Abstract
Many peptides in scorpion venoms are amidated at their C-termini. This post-translational modification is paramount for the correct biological function of ion channel toxins and antimicrobial peptides, among others. The discovery of canonical amidation sequences in transcriptome-derived scorpion proproteins suggests that a conserved enzymatic α-amidation system must be responsible for this modification of scorpion peptides. A transcriptomic approach was employed to identify sequences putatively encoding enzymes of the α-amidation pathway. A dual enzymatic α-amidation system was found, consisting of the membrane-anchored, bifunctional, peptidylglycine α-amidating monooxygenase (PAM) and its paralogs, soluble monofunctional peptidylglycine α-hydroxylating monooxygenase (PHMm) and peptidyl-α-hydroxyglycine α-amidating lyase (PALm). Independent genes encode these three enzymes. Amino acid residues responsible for ion coordination and enzymatic activity are conserved in these sequences, suggesting that the enzymes are functional. Potential endoproteolytic recognition sites for proprotein convertases in the PAM sequence indicate that PAM-derived soluble isoforms may also be expressed. Sequences potentially encoding proprotein convertases (PC1 and PC2), carboxypeptidase E (CPE), and other enzymes of the α-amidation pathway, were also found, confirming the presence of this pathway in scorpions.
Highlights
The order Scorpiones constitutes one of the most ancient lineages within the phylum Arthropoda [1,2].The key to the ecological success of these arachnids resides in the production of potent venoms used for feeding, defense, and deterring competitors [3,4]
A signal peptide sequence (SP) for secretion is followed by a short propeptide (PP) region, a PHM domain, a linker sequence (Linker 1), a PAL domain, a second linker sequence (Linker 2), a membrane spanning domain (MSD), and a cytosolic domain (CD)
Venom gland transcriptomic analyses performed with representative scorpion families from both both the Old and
Summary
The order Scorpiones constitutes one of the most ancient lineages within the phylum Arthropoda [1,2].The key to the ecological success of these arachnids resides in the production of potent venoms used for feeding, defense, and deterring competitors [3,4]. Scorpion venoms are complex mixtures of components, including bioactive peptides with potential therapeutic applications [4], enzymes, metabolites, and most importantly, an arsenal of toxins active on Na+ , K+ , Ca2+ , and Cl− channels [5,6,7,8,9,10]. The venom is produced and secreted by two symmetrical glands located in the last segment of the metasoma, the telson [12]. In these glands, the peptidyl venom components undergo synthesis and maturation, a complex process involving a series of post-translational modifications (PTMs) that result in the biologically active molecules [3]. Amidated toxins and peptides without disulfide bonds (NDBP) are well known in scorpion venoms (Table 1)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
