The complete atomic structure of the large ribosomal subunit at 2.4 angstrom resolution

The large ribosomal subunit catalyzes peptide bond formation and binds init iation, termination, and elongation factors. We have determined the crystal structure of the Large ribosomal subunit from Haloarcula marismortui at 2. 4 angstrom resolution, and it includes 2833 of the subunit's 3045 nucleotid es and 27 of its 31 proteins. The domains of its RNAs all have irregular sh apes and fit together in the ribosome Like the pieces of a three-dimensiona l jigsaw puzzle to form a Large, monolithic structure. Proteins are abundan t everywhere on its surface except in the active site where peptide bond fo rmation occurs and where it contacts the small subunit. Most of the protein s stabilize the structure by interacting with several RNA domains, often us ing idiosyncratically folded extensions that reach into the subunit's inter ior.