Structural dynamics of translating ribosomes

The main aim of the project is to monitor the structural dynamics of ribosomes using steady-state and time- resolved fluorescence resonance energy transfer measurements. The ribosomal and extra-ribosomal components and the general sequence of events orchestrated by them to perform protein synthesis in bacteria have long been known. However, the details of the mechanism by which the ribosome and associated factors construct a polypeptide accurately and rapidly are still unknown. Comprehending how the ribosome works is at the heart of molecular understanding of biology. The precise positioning and movements of ribosome-bound transfer RNA (tRNA), elongation factors EF-G and EF-Tu, and ribosomal RNA (rRNA) and ribosomal protein (r-protein) elements are essential for accurate and fast translation. The translocation step of protein elongation catalyzed by EF-G entails a large - scale rearrangement of the tRNA-mRNA-ribosome complex. Recent years have seen major advances in unraveling the mechanism of this process on the molecular level. A number of intermediate states have been defined and, in part, characterized structurally though many unanswered questions remain. One of the main questions is how the large and small subunits communicate between their active sites and how they interact with factors to promote the directional movements of translocation.