title: Only one 3'-hydroxyl group of ppp5' A2'p5'A2'p5' A (2-5A) is required for activation of the 2-5A-dependent endonuclease.
abstract: To investigate the relative importance of each of the ribose 3'-hydroxyl groups of 2-5A (ppp5' A2'p5'A2'-p5' A) in determining binding to and activation of the 2-5A-dependent endonuclease (RNase L), the 3'-hydroxyl functionality of each adenosine moiety of 2-5A trimer triphosphate was sequentially replaced by hydrogen. The analog in which the 5'-terminal adenosine was replaced by 3'-deoxyadenosine (viz. ppp5'(3'dA)-2'p5' A2'p5' A) was bound to RNase L as well as 2-5A itself and was only 3 times less potent than 2-5A as an activator of RNase L. On the other hand, when the second adenosine unit was replaced by 3'-deoxyadenosine (viz. ppp5' A2'p5'(3'dA)2'p5' A), binding to RNase L was decreased by a factor of eight relative to 2-5A trimer and, even more dramatically, there was a 500-1000-fold drop in ability to activate the 2-5A-dependent endonuclease. Finally, when the 3'-hydroxyl substituent was converted to hydrogen in the 2'-terminal residue of 2-5A, a significant increase in both binding and activation ability occurred. We conclude that only the 3'-hydroxyl group of the second (from the terminus) nucleotide residue of 2-5A is needed for effective activation of RNase L.
authors.affiliation: Laboratory of Analytical Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892.
authors.forename: P F
authors.initials: PF
authors.lastname: Torrence
authors.forename: D
authors.initials: D
authors.lastname: Brozda
authors.forename: D
authors.initials: D
authors.lastname: Alster
authors.forename: R
authors.initials: R
authors.lastname: Charubala
authors.forename: W
authors.initials: W
authors.lastname: Pfleiderer
mesh_terms: D000227:Adenine Nucleotides / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D004722:Endoribonucleases / Q000378:metabolism*; D004789:Enzyme Activation; D006900:Hydroxylation; D009690:Nucleic Acid Conformation; D009843:Oligoribonucleotides / Q000378:metabolism*; D013329:Structure-Activity Relationship
chemical_list: D000227:Adenine Nucleotides; D009843:Oligoribonucleotides; C023505:2',5'-oligoadenylate; D004722:Endoribonucleases; C031956:2-5A-dependent ribonuclease