I work on the mechanism of translation and the quality control systems that ensure fast and accurate protein synthesis in bacterial cells. Current work focuses on the function of pseudouridine, an isomer of uridine, in ribosomal RNA. While this modified base is found at conserved, functionally critical regions of the ribosomes in all organisms, our lab has shown that it is dispensable in two model bacteria, E. coli and Thermus thermophilus. We use genetic, biochemical and structural approaches to address why a dispensable, yet invariant feature of bacterial ribosomes has been conserved throughout evolution.