title: 2'-adenylated derivatives of Ap3A activate RNase L.
abstract: The exact physiological function of Ap3A (A5'ppp5"A, 5'5" diadenosine triphosphate) remains unclear. Previously we have demonstrated that the human p46 2-5A synthetase (OAS1) efficiently utilises Ap3A as an acceptor substrate for oligoadenylate synthesis. Here we show that Ap3A(2'p5'A)n oligonucleotides can activate the 2-5A-dependent RNase (RNase L), when the number of 2',5'-linked adenyl residues is two or more. Under the experimental conditions applied the half-maximal activation (AC50) of RNase L for 2'-adenylated Ap3A derivatives was determined to be in nanomolar range while the AC50 for 2-5A3 was 0.4 nM. The Ap3A(2'p5'A)n oligonucleotides are thus less effective in activating RNase L than 2-5A. We also investigated the occurrence of 2'-adenylated Ap3A in interferon and poly(I).poly(C)-treated HeLa cells. In purified trichloroacetic acid-soluble extracts about 40% of RNase L-activating material is resistant to phosphatase treatment, whereas the removal of 5'-terminal phosphates greatly reduces the activating properties of 2-5A. We assume that this activity at least partly may be associated with the presence of 2'-adenylated ApnA derivatives with blocked 5'-terminal phosphates.
authors.affiliation: Department of Molecular and Structural Biology, Aarhus University, Denmark.
authors.forename: K
authors.initials: K
authors.lastname: Turpaev
authors.forename: R
authors.initials: R
authors.lastname: Hartmann
authors.forename: J
authors.initials: J
authors.lastname: Justesen
mesh_terms: D015088:2',5'-Oligoadenylate Synthetase / Q000378:metabolism; D000469:Alkaline Phosphatase / Q000494:pharmacology; D016367:Baculoviridae / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D015226:Dinucleoside Phosphates / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004722:Endoribonucleases / Q000378:metabolism*; D004789:Enzyme Activation / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D007372:Interferons / Q000378:metabolism; D007700:Kinetics; D009841:Oligonucleotides / Q000494:pharmacology; D011994:Recombinant Proteins / Q000378:metabolism; D014238:Trichloroacetic Acid / Q000494:pharmacology
chemical_list: D015226:Dinucleoside Phosphates; D009841:Oligonucleotides; D011994:Recombinant Proteins; C011440:diadenosine triphosphate; D014238:Trichloroacetic Acid; D007372:Interferons; D015088:2',5'-Oligoadenylate Synthetase; D004722:Endoribonucleases; C031956:2-5A-dependent ribonuclease; D000469:Alkaline Phosphatase