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Phosphorothioates in pre-tRNAs can change the specificities of RNAses P or reduce the cleavage efficiencies

1993; Elsevier BV; Volume: 75; Issue: 11 Linguagem: Inglês

10.1016/0300-9084(93)90145-i

1638-6183

Dietmar Kahle, Britta Küst, Guido Krupp,

DNA and Nucleic Acid Chemistry

Several phosphorothioate-madified E coli and yeast pre-tRNAs were synthesized. If this modification included the phosphodiester at the RNase P cleavage site, two different effects were observed. With some pre-tRNAs the RNase P cleavage efficiency was severely reduced, whereas with other pre-tRNAs a new reaction type for RNase P was observed. Unlike the previously studied base or ribose modifications, phosphorothioates resulted in aberrant cleavages at unmodified phosphodiesters. These new sites could be located in the 5′-flank or in the acceptor stem of the tRNA domain. Modified mutants of E coli pre-tRNATyr with different base pairs at the RNase P cleavage site were cleaved with reduced efficiencies, but no aberrant products were observed.