Reactivity of modified ribose moieties of guanosine: new cleavage reactions mediated by the IVS of Tetrahymena precursor rRNA.

An RNA molecule consisting of the 5' exon and intervening sequence (IVS) of Tetrahymena precursor rRNA was oxidized with sodium periodate to convert the ribose moiety of the 3' terminal guanosine into a dialdehyde form. The modified RNA undergoes a specific cleavage reaction at the 5' splice site, but has no apparent cyclization activity. This novel reaction mediated by the IVS RNA is pH dependent over the range 6.5-8.5 and leaves a 5' phosphate and a 3'-OH at the newly created termini. The dialdehyde form of monomer guanosine is also capable of causing a specific cleavage reaction at the 5' splice site although the nucleotide is not covalently attached to the IVS RNA in the final product. These and other findings described in this report suggest that the cis diol of the intact ribose moiety of guanosine is not an absolute requirement for the IVS-mediated reactions.