Nonenzymatic hydrolysis of oligoribonucleotides.

Selective cleavage of phosphodiester bonds in RNA is important in the processing of large RNA molecules. This paper reports specific cleavage at UA sequences in single stranded oligoribonucleotides as short as hexamers. The hydrolysis between U and A leaves a 2',3'-cyclic phosphate on the 5'-side and a 5'-hydroxyl group on the 3' side of the cleavage. The hydrolysis is promoted by a wide range of cofactors, including polymeric organic compounds such as polyvinylpyrrolydone (PVP) and by proteins. A variety of experiments suggests the cleavage is not due to contamination by ribonuclease. The rate of cleavage is a function of oligoribonucleotide, PVP and spermidine concentrations. Mg2+ is not required. The phenomenon described here can potentially provide a relatively simple way of coding chemical stability into single stranded RNA based on its sequence and structure. This process seems to be similar to that involved in post-transcriptional degradation of mRNA.