Impairment of the Proteasome and Induction of Autophagy in Neurodegenerative Disease

The concept that the structure of the ribosome determines its function is simple. In practice, linking the two is not. Toward this general goal, we have undertaken an integrated approach employing the methods of molecular genetics, biochemistry, structural biology and molecular modeling in the model eukaryotic organism, Saccharomyces cerevisae. Both selected ribosomal proteins and rRNA residues have been targeted for this analysis. Core ribosomal proteins of the large subunit were chosen for mutagenesis and subsequent analyses based on their known and predicted effects on peptidyltransfer, tRNA binding, interactions with elongation factors, and intersubunit interactions. These include ribosomal proteins L2, L3, L5, L10, and L11. Specific bases of the 25S rRNA were selected for study based on similar criteria. These include bases in helix 38 (the A-site finger), helix 92 (the A-loop), helix 80 (the P-loop), and in the vicinity of the peptidyltransferase center. We have also completed extensive mutagenesis studies of 5S rRNA. Along the way, we have optimized a yeast genetic system for the stable generation of cells expressing only mutant rRNAs. Our investigations have also examined the roles of base modification on ribosome function. Base modification defects specific to the A-loop and to helix 93 were found to differentially affect specific ribosome-associated functions. The emerging picture is one in which individual components function both to make specific functional contributions, while simultaneously communicating these functions to one another over long distances within this complex nanomachine. *Presenter. Email address: [email protected]