A novel endoribonuclease from the marine sponge Tethya aurantium specific to 2鈥?5鈥?phosphodiester bonds

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• 作者：Annika Lopp^a ; Tõ ; nu Reintamm^a ; Anne Kuusksalu^a ; Salvatore de Rosa^b ; Merike Kelve^a ; ^{merike.kelve@ttu.ee}
• 关键词：Endo-2&prime ; 5&prime ; -ribonuclease ; 2&prime ; 5&prime ; -Phosphodiester bond ; 5&prime ; -Triphosphorylated 2&prime ; 5&prime ; -linked oligonucleotides ; 2-5A degradation ; Porifera
• 刊名：Biochimie
• 出版年：2012
• 期刊代码：24_03009084
• 类别：bio
• 出版时间：August, 2012
• 卷：94
• 期：8
• 页码：1635-1646
• 文件大小：696 K

摘要

In the marine sponge Tethya aurantium a novel endoribonuclease was found which specifically catalyzed the degradation of 2鈥?5鈥?phosphodiester linkages and was therefore named endo-2鈥?5鈥?ribonuclease. This enzymatic reaction yielded 2鈥?3鈥?cyclic phosphate and 5鈥?OH products similarly to the 3鈥测€?鈥?bond cleavage in RNA, catalyzed by metal-independent ribonucleases. The partially purified enzyme preparation was used for its biochemical characterization. The enzyme did not require the presence of metal ions for its activity. The novel nuclease exhibited a preference for 5鈥?phosphorylated 2鈥?5鈥?oligoadenylates, but 2鈥测€?鈥?linkage in 5鈥?triphosphorylated hetero-oligomers or homo-dimers comprising guanylate or uridylate residues instead of adenylate was cleaved as well. The enzyme was also able to catalyze the degradation of 5鈥?unphosphorylated 2鈥?5鈥?oligoadenylates, except for 2鈥?5鈥?diadenylate, which were weaker substrates for the enzyme than the respective 5鈥?triphosphorylated forms. The observed substrate specificity may refer to the specific role of the enzyme in the degradation of natural 2鈥?5鈥?oligoadenylates (2-5A) that function in the interferon-induced mammalian 2-5A system as allosteric regulators of ribonuclease L. They are produced by 2-5A synthetases (OAS) that are also present in sponges, the most ancient phylum of Metazoa. We suggest that the newly discovered endoribonuclease found in the marine sponge T.聽aurantium could be a representative of the group of 2鈥?5鈥?specific ribonucleases that primarily control the cellular levels of 2鈥?5鈥?oligoadenylates.