Twister sister ribozyme

The twister sister ribozyme (TS) is an RNA structure that catalyzes its own cleavage at a specific site.

[1] The crystal structures of the pre-catalytic state of the twister sister ribozymes were solved by two research groups independently.

[2] The active site, a scissile phosphate, is located in a loop with quasihelical character in one coaxial base-stacked helix.

[3] The active site of a four-way junctional twister sister is splayed-apart with an interaction between guanine and scissile phosphate.

For the four-way junctional twister sister, Ren and coworkers find that guanine with an amino group is likely to play a role in the catalysis because G5 mutations result in very low catalytic activity.

The formation of a pseudoknot for four-way junctional TS was found to be highly Mg2+ dependent by conducting SHAPE (Selective-2′ -Hydroxyl Acylation analyzed by Primer Extension) experiments.

Schematic and tertiary structure of the twister-sister ribozyme. a Schematic of the secondary fold of the dC62-containing four-way junctional twister-sister ribozyme. b Schematic of the tertiary fold based on the crystal structure of the dC62-containing four-way junctional twister-sister ribozyme. c A ribbon view of the 2 Å structure of the four-way junctional twister-sister ribozyme color-coded as shown in a and b. The divalent metal ions identified in the tertiary structure are shown as green balls. d Highly conserved residues (shown in red) are brought into close proximity by the interaction between partially zippered-up L1 and SL4 loops in the tertiary fold of the twister-sister ribozyme