The many faces of the hairpin ribozyme: structural and functional variants of a small catalytic RNA.

The hairpin ribozyme is a small catalytic RNA that has been reengineered resulting in a number of variants with extended or even new functions. Thus, manipulation of the hairpin ribozyme structure has allowed for activity control by external effectors, namely oligonucleotides, flavine mononucleotide, and adenine. Hairpin ribozyme-derived twin ribozymes that mediate RNA fragment exchange reactions as well as self-processing hairpin ribozymes were designed. Furthermore, several hairpin ribozyme variants have been engineered for knock down of specific RNA substrates by adapting the substrate-binding domain to the specific target sequence. This review will focus on hairpin ribozymes possessing structural extensions/variations and thus functionally differing from the parent hairpin ribozyme. (C) 2011 IUBMB, IUBMB Life,, 2011.