Understanding the molecular principles governing mRNP architecture

Eukaryotic messenger ribonucleoprotein (mRNP) particles are the functional entities that carry genetic information to the protein synthesizing machinery. These ribonucleoprotein complexes are dynamic and diverse, as highlighted by the copious number of proteins and transcripts identified in global proteomic and transcriptomic studies. However, little is known about the composition and architecture of individual mRNPs, and how changes in mRNP structure relate to their function or to dysfunction. The GOVERNA project will address this gap in knowledge by purifying specific mRNPs and delving into their molecular and structural arrangement. With our preliminary data serving as a springboard, the project combines genomic tagging engineered to maintain the most physiologically relevant conditions, biochemical methods developed to preserve the integrity of transient ribonucleoprotein assemblies, and mass spectrometry and cryo-electron microscopy to identify the composition and architecture of mRNPs. We will zoom-in on a set of paradigms in RNA biology that not only sample the breadth of mRNP diversity, but are also powerful model systems for linking structural information and biological function. We will investigate the molecular features in the three-dimensional organization of nuclear mRNPs from S. cerevisiae and of translationally repressed mRNPs in early developmental stages in D. melanogaster and X. laevis. For mRNPs undergoing active translation, we will investigate the transitions of human beta-globin mRNPs in the course of a surveillance process connected to disease. By studying these examples, we will glean fundamental insights into global principles governing the packaging of mRNPs and the remodeling of their three-dimensional features throughout a transcript’s life-cycle. The cumulative output will illuminate a central node of eukaryotic gene expression that is also particularly timely and relevant given recent developments in mRNA-based therapeutics.