High resolution structure of the large ribosomal subunit from a mesophilicEubacterium

We describe the high resolution structure of the large ribosomal subunit fr om Deinococcus radiodurans (D50S), a gram-positive mesophile suitable for b inding of antibiotics and functionally relevant ligands. The overall struct ure of D50S is similar to that from the archae bacterium Haloarcula marismo rtui (H50S); however, a detailed comparison revealed significant difference s, for example, in the orientation of nucleotides in peptidyl transferase c enter and in the structures of many ribosomal proteins. Analysis of ribosom al features involved in dynamic aspects of protein biosynthesis that are pa rtially or fully disordered in H50S revealed the conformations of intersubu nit bridges in unbound subunits, suggesting how they may change upon subuni t association and how movements of the L1-stalk may, facilitate the exit of tRNA.