Oligoribonucleotides containing 2',5'-phosphodiester linkages exhibit binding selectivity for 3',5'-RNA over 3',5'-ssDNA.
Oligoribonucleotides containing 2',5'-phosphodiester linkages have been synthesized on a solid support by the 'silyl-phosphoramidite' method. The stability of complexes formed between these oligonucleotides and complementary 3',5'-RNA strands have been studied using oligoadenylates and a variety of oligonucleotides of mixed base sequences including phosphorothioate backbones. In many cases, particularly for 2',5'-linked adenylates, the UV melting profiles are quite sharp and exhibit large hyperchromic changes. Substituting a few 3',5'-linkages with the 2',5'-linkage within an oligomer lowers the Tm of the complex and the degree of destabilization depends on the neighboring residues and neighboring linkages. The 2',5'-linked oligoribonucleotides prepared in this study exhibited remarkable selectivity for complementary single stranded RNA over DNA. For example, in 0.01 M phosphate buffer--0.10 M NaCl (pH 7.0), no association was observed between 2',5'-r(CCC UCU CCC UUC U) and its Watson-Crick DNA complement 3',5'-d(AGAAGGGAGAGGG). However, 2',5'-r(CCC UCU CCC UUC U) with its RNA complement 3',5'-r(AGAAGGGAGAGGG) forms a duplex which melts at 40 degrees C. The decamer 2',5'-r(Ap)9A forms a complex with both poly dT and poly rU but the complex [2',5'-r(Ap)9A]:[poly dT] is unstable (Tm, -1 degree C) and is seen only at high salt concentrations. In view of their unnatural character and remarkable selectivity for single stranded RNA, 2',5'-oligo-RNAs and their derivatives may find use as selective inhibitors of viral mRNA translation, and as affinity ligands for the purification of cellular RNA.
Giannaris
P A
PA
Department of Chemistry, McGill University, Montreal, Quebec, Canada.
Damha
M J
MJ
D001483:Base Sequence; D004277:DNA, Single-Stranded / Q000378:metabolism*; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009690:Nucleic Acid Conformation; D009843:Oligoribonucleotides / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism*; D010755:Organophosphates / Q000737:chemistry / Q000378:metabolism*; D011071:Poly T / Q000378:metabolism; D011072:Poly U / Q000378:metabolism; D012313:RNA / Q000378:metabolism*; D013696:Temperature
D004277:DNA, Single-Stranded; D009843:Oligoribonucleotides; D010755:Organophosphates; D011071:Poly T; D011072:Poly U; D012313:RNA