title: Oligonucleotide facilitators enable a hammerhead ribozyme to cleave long RNA substrates with multiple-turnover activity.
abstract: Trans-acting hammerhead ribozymes are usually efficient in cleaving short RNA model substrates under both single-turnover and multiple-turnover conditions. In contrast, when long RNAs are the substrates, the cleavage efficiency of these ribozymes decreases, including a loss of multiple-turnover activity in many cases. Since target substrates for potential therapeutical purposes are mostly long RNAs, a multiple-turnover cleavage of long RNAs would essentially increase the efficiency of hammerhead ribozymes. Therefore, we explored if oligonucleotide facilitators, capable of enhancing multiple-turnover activity with short substrates, can also affect or cause multiple turnover with long substrates. We examined the effects of 12-base and 24-base oligonucleotide facilitators on the multiple-turnover activity with substrates of different length containing 39-, 452- and 942-base sequences of the human tissue factor (HTF) mRNA. In the absence of facilitator, the ribozyme cleaved only the 39-base substrate with multiple-turnover activity, but not the long 452-base and 942-base substrates. However, facilitator addition enabled the ribozyme to cleave even the 452-base and the 942-base substrates with multiple-turnover activity. All facilitators tested showed a remarkable activating effect with the long substrates. The data demonstrate that a hammerhead ribozyme which, by itself, can only act as a single-turnover catalyst with long substrates, can be switched by facilitators into a multiple-turnover catalyst. Thus, the inactivation of long target RNAs in multiple-turnover reactions may be achieved by addition of oligonucleotide facilitators.
authors.affiliation: Institut für Biochemie, Technische Universität Dresden, Germany.
authors.forename: E
authors.initials: E
authors.lastname: Jankowsky
authors.forename: B
authors.initials: B
authors.lastname: Schwenzer
mesh_terms: D006801:Humans; D007700:Kinetics; D009690:Nucleic Acid Conformation; D009841:Oligonucleotides / Q000494:pharmacology; D016337:RNA, Catalytic / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism*; D013379:Substrate Specificity; D013925:Thromboplastin / Q000235:genetics*
chemical_list: D009841:Oligonucleotides; D016337:RNA, Catalytic; D012333:RNA, Messenger; D013925:Thromboplastin