Scientists have discovered a new class of enzymes that use a type of RNA to make natural products, according to a study published online this week in Nature Chemical Biology. Transfer RNA, called tRNA, add amino acids to a growing chain of amino acids that becomes a protein. However, in this study Jean-Luc Pernodet and colleagues report on tRNA assisting in secondary metabolism, widening the function of this central biomolecule.

There are many natural products that include certain amino acids joined into a small ring, but it has not been known how these rings are made. The scientists now identify a group of enzymes that make these molecules. The enzymes are unusual in that they do not have a way to harness ATP, the biological currency of energy, to generate the energy needed to perform the reaction. However, the authors solve this mystery by demonstrating that the enzymes use activated tRNAs those with an amino acid already 'energized' by being attached to the RNA to complete the reaction. This result expands our understanding of tRNA function and establishes a completely new biosynthetic pathway.