THE EFFECT OF LP3 ENLARGEMENT ON THE FOLDING AND CATALYSIS OF HEPATITIS-DELTA VIRUS CIS-CLEAVING RIBOZYME

Oligonucleotides were inserted into the Lp3 region of a hepatitis delt a virus (HDV) cis-cleaving ribozyme and the effect of Lp3 enlargement on ribozyme folding was examined by assaying the activity of each muta nt. The location of insertion and the sequence of the inserted oligonu cleotide had distinct effects on ribozyme activity, and the HDV ribozy me was capable of adopting the active structure for cis-cleavage when a pentanucleotide was inserted into the 3' portion of Lp3, Furthermore , whether the insertion mutant cis-cleaved or not, the structure of Lp 3 was altered by the inserted oligonucleotide, These findings disclose that the 5' rather than the 3' portion of Lp3 is critical for ribozym e folding and catalysis. (C) 1998 Federation of European Biochemical S ocieties.