hairpinribozymeja

Hairpin ribozymes are small self-cleaving RNA motifs that catalyze site-specific RNA cleavage through a transesterification reaction. They occur naturally in viroids and viroid-like satellite RNAs, and are among the best studied self-cleaving ribozymes after the hammerhead ribozyme. Hairpin ribozymes typically comprise about 50 to 60 nucleotides and fold into a compact hairpin structure with two helical segments converging on a catalytic core.

The catalytic core is formed by conserved sequence and base-pairing interactions within the loops and stems, bringing the scissile phosphate into position for catalysis. The cleavage reaction yields a 2',3'-cyclic phosphate and a 5'-hydroxyl terminus. Catalysis relies on a combination of RNA functional groups acting as general acids and bases, in concert with bound divalent metal ions such as Mg2+, which aid in proton transfer and stabilization of the transition state.

In natural systems, hairpin ribozymes participate in processing of replication intermediates and regulation of RNA activity in viroids and satellite RNAs. In laboratory contexts, they have been developed as trans-acting catalysts capable of cleaving designed RNA targets, providing tools for gene regulation, RNA tagging, and molecular biology research.

Compared with other small self-cleaving ribozymes, the hairpin ribozyme has a distinct sequence and structural organization but shares common themes of compact folding and metal-dependent catalysis. Its study has contributed to broader insights into RNA catalysis and the potential uses of ribozymes in biotechnology.