RNA, the first macromolecular catalyst: the ribosome is a ribozyme.

Recently, the atomic structures of the large ribosomal subunit from Haloarcula marismortui and its complexes with substrates have been determined. These have provided exciting new insights into the principles of RNA structure, the mechanism of the peptidyl-transferase reaction and early events in the evolution of this RNA-protein complex assembly that is essential in all cells. The structures of the large subunit bound to a variety of antibiotics explain the effects of antibiotic resistance mutations and provide promise for the development of new antibiotics.