title: A novel endoribonuclease from the marine sponge Tethya aurantium specific to 2',5'-phosphodiester bonds.
abstract: In the marine sponge Tethya aurantium a novel endoribonuclease was found which specifically catalyzed the degradation of 2',5'-phosphodiester linkages and was therefore named endo-2',5'-ribonuclease. This enzymatic reaction yielded 2',3'-cyclic phosphate and 5'-OH products similarly to the 3'-5' 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'-phosphorylated 2',5'-oligoadenylates, but 2'-5' linkage in 5'-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'-unphosphorylated 2',5'-oligoadenylates, except for 2',5'-diadenylate, which were weaker substrates for the enzyme than the respective 5'-triphosphorylated forms. The observed substrate specificity may refer to the specific role of the enzyme in the degradation of natural 2',5'-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. aurantium could be a representative of the group of 2',5'-specific ribonucleases that primarily control the cellular levels of 2',5'-oligoadenylates.
authors.affiliation: Department of Gene Technology, Tallinn University of Technology, Akadeemia tee 15, 12618 Tallinn, Estonia.
authors.forename: Annika
authors.initials: A
authors.lastname: Lopp
authors.forename: Tõnu
authors.initials: T
authors.lastname: Reintamm
authors.forename: Anne
authors.initials: A
authors.lastname: Kuusksalu
authors.forename: Salvatore
authors.initials: S
authors.lastname: de Rosa
authors.forename: Merike
authors.initials: M
authors.lastname: Kelve
mesh_terms: D000818:Animals; D002384:Catalysis; D004722:Endoribonucleases / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D004952:Esters / Q000737:chemistry; D007372:Interferons / Q000737:chemistry / Q000378:metabolism; D011161:Porifera / Q000201:enzymology*; D012313:RNA / Q000737:chemistry*; D013379:Substrate Specificity
chemical_list: D004952:Esters; D012313:RNA; D007372:Interferons; D004722:Endoribonucleases