title: 2',5'-oligoadenylate synthetase from a lower invertebrate, the marine sponge Geodia cydonium, does not need dsRNA for its enzymatic activity.
abstract: Recently, the presence of 2',5'-linked oligoadenylates and a high 2',5'-oligoadenylate synthetase activity were discovered in a lower invertebrate, the marine sponge Geodia cydonium. It has been demonstrated that mammalian 2-5A synthetase isozymes require a dsRNA cofactor for their enzymatic activity. Our results show that, unlike mammalian 2-5A synthetases, the 2-5A synthetase from the sponge acts in a dsRNA-independent manner in vitro. A prolonged incubation of the G. cydonium extract with a high concentration of a micrococcal nuclease had no effect on the activity of the 2-5A synthetase. At the same time, the micrococcal nuclease was effective within 30 min in degrading dsRNA needed for the enzymatic activity in IFN-induced PC12 cells. These results indicate that the 2-5A synthetase from G. cydonium may be active per se or is activated by some other mechanism. The sponge enzyme is capable of synthesizing a series of 2-5A oligomers ranging from dimers to octamers. The accumulation of a dimer in the predominant proportion during the first stage of the reaction was observed, followed by a gradual increase in longer oligoadenylates. By its product profile and kinetics of formation, the sponge 2-5A synthetase behaves like a specific isoform of enzymes of the 2-5A synthetase family.
authors.affiliation: Laboratory of Molecular Genetics, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618, Tallinn, Estonia.
authors.forename: Annika
authors.initials: A
authors.lastname: Lopp
authors.forename: Anne
authors.initials: A
authors.lastname: Kuusksalu
authors.forename: Tõnu
authors.initials: T
authors.lastname: Reintamm
authors.forename: Werner E G
authors.initials: WE
authors.lastname: Müller
authors.forename: Merike
authors.initials: M
authors.lastname: Kelve
mesh_terms: D015088:2',5'-Oligoadenylate Synthetase / Q000302:isolation & purification / Q000378:metabolism*; D000227:Adenine Nucleotides / Q000096:biosynthesis; D000818:Animals; D004800:Enzymes, Immobilized; D006863:Hydrogen-Ion Concentration; D007369:Interferon Inducers / Q000494:pharmacology; D008836:Micrococcal Nuclease; D009843:Oligoribonucleotides / Q000096:biosynthesis; D016716:PC12 Cells; D011070:Poly I-C / Q000494:pharmacology; D011161:Porifera / Q000201:enzymology*; D012330:RNA, Double-Stranded / Q000378:metabolism; D051381:Rats; D013045:Species Specificity; D013379:Substrate Specificity
chemical_list: D000227:Adenine Nucleotides; D004800:Enzymes, Immobilized; D007369:Interferon Inducers; D009843:Oligoribonucleotides; D012330:RNA, Double-Stranded; C023505:2',5'-oligoadenylate; D015088:2',5'-Oligoadenylate Synthetase; D008836:Micrococcal Nuclease; D011070:Poly I-C