TOWARDS ARTIFICIAL RIBONUCLEASES - THE SEQUENCE-SPECIFIC CLEAVAGE OF RNA IN A DUPLEX

Lanthanide complexes covalently attached to oligonucleotides have been shown to cleave RNA in a sequence-specific manner. Efficient cleavage , however, is at present limited to single-stranded RNA regions, as RN A in a duplex is considerably more resistant to strand scission. To ov ercome this limitation, we have designed and synthesised artificial nu cleases comprising lanthanide complexes covalently linked to oligodeox yribonucleotides which cleave a partially complementary RNA at a bulge d site, in the duplex region. Strand scission occurs at or near the bu lge. Cleavage of the RNA target by the metal complex can be addressed via the major or the minor groove. In an example of a competitive situ ation, where the cleavage moiety has access to both a bulge and a sing le-strand region, transesterification at the bulge is favoured. Such a rtificial ribonucleases may find application as antisense agents and a s tools in molecular biology. In addition, the results may have import ance for the design of artificial ribonucleases which are able to act with catalytic turnover.