Twister ribozyme
The twister ribozyme[1] is an RNA structure that catalyzes its own cleavage at a specific site. In other words, it is a self-cleaving ribozyme. It was discovered using a bioinformatics based approach.
Twister Catalysis:
Twister ribozyme like most other small self cleaving ribozymes cleaves a specific phopshodiester bond into two products: a 5' product containing 2'3' -cyclic phosphate on the 3' end and a 3' product with a 5' hydroxyl. So far, it is known that rate of reaction of twister is affected by pH and divalent metals. Metals increase the rate of reaction, however, they most likely play a structural role since the rate of the reaction seemed to be same in different divalent metals.[1] A hill shaped pH-rate profile indicates that there is probably a general acid-general base catalysis involved like the hammerhead ribozyme. However, conclusive evidence for acid-base catalysis is still being pursued.
The twister ribozyme is present in certain bacterial and eukaryotic organisms. Similarly to hammerhead ribozymes, some eukaryotes contain large numbers of twister ribozymes. In the most extreme known example, there are 1051 predicted twister ribozymes in Schistosoma mansoni, an organism that also contains many hammerhead ribozymes. In bacteria, twister ribozymes are near to gene classes that are also commonly associated with bacterial hammerhead ribozymes.
Atomic-resolution structures of examples of twister ribozymes were determined. [2] [3] [4]
