Abstract
An enzyme in a nematocyst extract of the Nemopilema nomurai jellyfish, caught off the coast of the Republic of Korea, catalyzed the cleavage of chymotrypsin substrate in an amidolytic kinetic assay, and this activity was inhibited by the serine protease inhibitor, phenylmethanesulfonyl fluoride. We isolated the full-length cDNA sequence of this enzyme, which contains 850 nucleotides, with an open reading frame of 801 encoding 266 amino acids. A blast analysis of the deduced amino acid sequence showed 41% identity with human chymotrypsin-like (CTRL) and the CTRL-1 precursor. Therefore, we designated this enzyme N. nomurai CTRL-1. The primary structure of N. nomurai CTRL-1 includes a leader peptide and a highly conserved catalytic triad of His69, Asp117, and Ser216. The disulfide bonds of chymotrypsin and the substrate-binding sites are highly conserved compared with the CTRLs of other species, including mammalian species. Nemopilema nomurai CTRL-1 is evolutionarily more closely related to Actinopterygii than to Scyphozoan (Aurelia aurita) or Hydrozoan (Hydra vulgaris). The N. nomurai CTRL1 was amplified from the genomic DNA with PCR using specific primers designed based on the full-length cDNA, and then sequenced. The N. nomurai CTRL1 gene contains 2434 nucleotides and four distinct exons. The 5′ donor splice (GT) and 3′ acceptor splice sequences (AG) are wholly conserved. This is the first report of the CTRL1 gene and cDNA structures in the jellyfish N. nomurai.
Highlights
Serine proteases are enzymes that hydrolyze specific peptide bonds in proteins via an activated serine residue in their substrate-binding sites [1]
Many physiological processes are regulated by chymotrypsin-like proteases, including apoptosis, signal transduction [6,7], reproduction [8], hemostasis, and immune responses [9]
The nematocyst extract of N. nomurai was assayed for amidolytic activity using several substrates
Summary
Serine proteases are enzymes that hydrolyze specific peptide bonds in proteins via an activated serine residue in their substrate-binding sites [1]. They have a number of physiological and Toxins 2016, 8, 205; doi:10.3390/toxins8070205 www.mdpi.com/journal/toxins. There are several serine proteases that have been characterized as toxins in the venoms of poisonous animals, including snakes, bees, etc. In snake venom, they can inhibit blood coagulation in victims and spread toxic components throughout the bloodstream [14]. (CTRL-1) from the jellyfish N. nomurai, collected off the coast of Korea
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