Numerous interactions act redundantly to assemble a tunable size of P bodies in Saccharomyces cerevisiae

Abstract

Eukaryotic cells contain multiple RNA–protein assemblies referred to as RNP granules, which are thought to form through multiple protein–protein interactions analogous to a liquid–liquid phase separation. One class of RNP granules consists of P bodies, which consist of nontranslating mRNAs and the general translation repression and mRNA degradation machinery. P bodies have been suggested to form predominantly through interactions of Edc3 and a prion-like domain on Lsm4. In this work, we provide evidence that P-body assembly can be driven by multiple different protein–protein and/or protein–RNA interactions, including interactions involving Dhh1, Psp2, and Pby1. Moreover, the relative importance of specific interactions can vary with different growth conditions. Based on these observations, we develop a summative model wherein the P-body assembly phenotype of a given mutant can be predicted from the number of currently known protein–protein interactions between P-body components.