Role of the Obg proteins in Saccharomyces cerevisiae

Regents Of The University Of Michigan - Ann Arbor, Ann Arbor MI

Investigators

Abstract

All proteins in the cell are synthesized by the activity of ribosomes. Ribosomes are composed of large and small ribosomal subunits (60S and 40S, respectively). In the yeast, the mature 60S ribosomal subunit contains 46 proteins and three rRNAs while the mature 40S ribosomal subunit contains 32 proteins and the one rRNA. The assembly of these ribosomal particles occurs via an ordered series of complexes as additional ribosomal proteins are added, and rRNA is cleaved and modified. Throughout this process, non-ribosomal proteins aid in requisite modifications and conformational changes. The processing and modification events leading to the mature rRNAs are relatively well understood. In contrast, however, the events that lead to the assembly of the rRNAs with the ribosomal proteins are poorly understood. Critical to ribosome assembly is the function of a GTP-binding protein, Nog1p. Nog1p is essential for 60S subunit assembly and it is likely that GTP hydrolysis by Nog1p is required for a critical remodeling step of the pre-60S ribosomal subunit. This research focuses on characterizing Nog1p and its role in 60S assembly. In particular, the GTP binding and hydrolysis characteristics of Nog1p will be determined in order to predict how it may function in the cell. Further, the relationship between Nog1p and the pre-60S ribosomal subunits will be investigated using a variety of genetic and biochemical approaches. Finally, the proteins and/or rRNA that interact with Nog1p will be identified and characterized such that their relationships will be elucidated. These studies will result in a greater understanding of how the cell orchestrates the temporal assembly of a large and complicated protein-RNA complex.