Inter-Subunit Communication in the Bacterial Ribosome

University Of Missouri-Kansas City, Columbia MO

Investigators

Abstract

The ribosome is the site of protein synthesis in all cells and invariably consists of two unequally sized subunits that carry out the sequential steps of translation. The mechanisms responsible for coordinating these activities are largely unknown and are the subject of this project. Ribosomal subunits are connected by a series of bridges and structural analysis has shown that these bridges move during the translocation phase of translation. Moreover, alterations to the large (50S) subunit component of one of the bridge B2a, affects decoding on the small (30S) subunit while changes in the 30S subunit can compensate for lethal bridge mutations in the 50S subunit. Together, these data suggest that bridges may coordinate the activities of the two subunits by serving both as conduits of information within the ribosome as well as by driving the relative movement between subunits. The roles of intersubunit bridges in translation will be addressed by designing mutant Escherichia coli ribosomes with altered bridge contacts. The defects of the mutant ribosomes will then be characterized in a series of in vivo and in vitro functional assays that measure the individual steps of translation. Structural characterization of mutant ribosomes and the isolation of secondary, suppressor mutations that compensate for the defects of inviable bridge mutants will allow the identification of a network of functional interactions between the ribosomal subunits. Together these approaches will allow functional and genetic data to be integrated with vast amount of information available on ribosome structure.