Molecular cloning and sequence analysis of serine protease cDNA from the venom of the centipede

Objective: Proteolytic enzymes are one of the well-known components of animal venom. The aim of this study was to identify protease from the venom gland of Scolopendra subspinipes dehaani. Methods: After total RNA extraction, a cDNA encoding a serine protease was identified by RT-PCR and was subsequently sequenced. The sequence was analysed by multiple alignment and homology modelling. Results: A cDNA encoding the precursor of a centipede venom serine protease was identified. The full-length cDNA was 1,014 nucleotides with 780 nucleotides of open reading frame. The precursor nucleotide sequence encoded a signal peptide of 19 residues and a mature protein of 260 residues. It belonged to clan PA of serine proteases in the MEROPS database classification. Catalytic residues were identified by multiple alignments, including an unusual hydrogen bond network in the catalytic site. Secondary structure prediction and homology modelling revealed a chymotrypsin-like fold, which is characteristic of PA clan proteases. Conclusion: The sequence of the identified serine protease showed unusual features, making this centipede venom serine protease an interesting candidate to investigate. A better understanding of the molecular mechanism of venom components will be useful for further applications and help to improve envenomation treatment.