Catalytic RNA

Abstract Ribonucleic acid (RNA) molecules have diverse roles in biological systems. Although some code for proteins or act to translate codons to amino acids, others fold into specific shapes that endow them with the ability to catalyse specific chemical transformations. These catalytic RNAs, ribozymes, are responsible for protein synthesis, transfer RNA (tRNA) processing, self‐splicing of certain introns, self‐scission during rolling circle replication of some single‐stranded RNA viruses and cofactor‐dependent gene regulation in bacteria. Other ribozymes have been evolved in vitro to perform a wide variety of transformations. Two of these, tRNA aminoacylase and RNA polymerase ribozymes, are featured here because molecules with such capabilities are thought to have existed on early Earth, before proteins took over as the dominant biological catalysts. Most of the ribozymes have been shown to perform multiturnover catalysis and thus act as true enzymes, either in their natural, biological form or as engineered constructs. Key Concepts: RNA molecules can fold into specific conformations and accelerate chemical transformations, thus acting as catalytic biomacromolecules, ribozymes. Ribozymes can accelerate chemical reactions by many orders of magnitude. Many ribozymes are capable of multiturnover catalysis, acting as enzymes. Protein synthesis templated by mRNA is catalysed by ribosomal RNA. Most ribozymes are phosphoryl transferases. In vitro selected ribozymes have been shown to catalyse a wide variety of reactions. The existence of ribozymes supports the RNA World hypothesis.