Staphylococcus aureus domain V functions in Escherichia coli ribosomes provided a conserved interaction with domain IV is restored

Domain V of Escherichia coli 23 S rRNA (residues 2023-2630) was replaced by that from Staphylococcus aureus, thereby introducing 132 changes in the rR NA sequence. The resulting ribosomal mutant was unable to support cell grow th. The mutant was rescued, however, by restoring an interaction between do mains IV and V (residues 1782 and 2586). Although the importance of this in teraction, U/U in E. coli, C/C in S. aureus, Is therefore demonstrated, it cannot be the only tertiary interaction important for ribosomal function as the rescued hybrid grew more slowly than the wild type. Additionally, alth ough the single-site mutations U1782C and U2586C in E. coli are viable, the double mutant is lethal.