New Class Of Ribozymes Found

For the first time in almost a decade, biochemists have found a new class of ribozymes. These molecules are ribonucleic acids that catalyze chemical reactions and may play a role in gene regulation. By using bioinformatics tools to mine genome sequences, Ronald R. Breaker and coworkers at Yale University have found a new class of self-cleaving ribozymes, which they have dubbed twister ribozymes because their structural motif—three loops connected by double-stranded stems—resembles an Egyptian hieroglyph that translates as “twisted flax” (Nat. Chem. Biol. 2013, DOI: 10.1038/nchembio.1386). In addition to the core structural motif, the ribozymes also have two pseudoknots (structures that look like knots but aren’t actually knots in a topological sense) that are necessary for catalysis. The researchers originally found the twister ribozymes in Clostridia bacteria, but they have since identified them in many other bacteria and in some eukaryotes. They have found a total of almost 2,700 twister ribozymes so far. The ribozymes tend to be found in the same region of bacterial genomes as hammerhead ribozymes, suggesting that the two types of ribozymes may be functionally interchangeable.