Abstract:One unique and highly compartmentalized sea cucumber superoxide dismutase gene MnSOD has been cloned and characterized. The full-length MnSOD cDNA of sea cucumber was comprised of 955bp, containing a 672bp open reading frame (ORF), 216bp 3′UTR and 67bp 5′UTR. The full-length MnSOD cDNA had an ATTTA deoxyadenosine monophosphate signal sequence in 3′ UTR and a polyA in the end, which is consistent with the characteristics of effective length of gene translation. Sequence comparison showed that the MnSOD shares 61%~69% similarity with MnSOD of Homo sapiens, Bos taurus, Gallus gallus,Xenopus laevis,Danio rerio,Haliotis discus,Argopecten irradians,Fenneropenaeus chinensis,and Drosophila melanogaster.The full-length MnSOD cDNA encoded 223 amino acids with protein molecule of 24.64 kD, andisoelectric of 6.66. The SOD had 17 alkaline amino acids, 20 strongly acidic amino acids, 83 hydrophobic amino acids, and 59 polar amino acids. The protein sequence had no signal peptide or transmembrane structure, only a mitochondrial leading peptide. The secondary structure was mainly comprised of alpha helix, with the largest number of irregular coiling and chain in the whole protein, without folding. The InterPro software analysis showed that the sequence of amino acids contains three protein kinase C phosphorylation sites, one casein kinaseⅡ phosphorylation site, 5 nutmeg acylation sites, and an SOD family signature peptide DVWEHAYY. The protein had 1 serine and 3 threonines, which were possibly protein kinase phosphorylation sites. Disulfide bond analysis showed that MnSOD contained three cysteines , forming a disulfide bond by connecting the 17th and 107th Cysteines. The cloning of MnSOD cDNAwould be helpful for better understanding of the body defense system to eliminate active oxygen O-2and maintain the metabolism balance.
