UC Berkeley

At all stages of a messenger RNA’s lifecycle, it is covered in RNA-binding proteins. These proteins regulate an RNA transcript’s splicing and processing in the nucleus, its export from the nucleus into the cytoplasm, its localization and translation in the cytoplasm, and its eventual turnover and decay. Despite knowing the identities of roughly 700 RNA-binding proteins in budding yeast, the role in RNA regulation that many of these proteins perform remains unclear. Here we present two studies that are aimed at the functional characterization of proteins that regulate post-transcriptional gene expression. In the first study, we devised a high-throughput tethering assay for the characterization of proteins on a proteome-wide scale. This novel assay provides domain-level resolution for the functional regions of proteins and identifies their regulatory activity in a quantitative manner. In the second study, we characterized the yeast RNA-binding protein Mrn1p and found that it is a dynamic regulator of post-transcriptional regulation that functions through mRNA turnover. Mrn1p is especially important in linking cell wall biogenesis with mitochondrial homeostasis, and it regulates these two cellular compartments in a manner that is responsive to carbon source and cell stress. Together, we present two studies that provide new functional information about yeast RNA binding proteins, with broad implications for a better understanding of post-transcriptional gene expression.