mRNA localization to P-bodies in yeast is bi-phasic with many mRNAs captured in a late Bfr1p-dependent wave

Abstract

The relocalization of translationally repressed mRNAs to mRNA Processing bodies (P-bodies) is a key consequence of cellular stress across many systems. P-bodies harbor mRNA degradation components and are implicated in mRNA decay, but the relative timing and control of mRNA relocalization to P-bodies is poorly understood. We used the MS2-GFP system to follow the movement of specific endogenous mRNAs in live yeast cells after nutritional stress. It appears that the relocalization of mRNA to P-bodies after stress is bi-phasic: some mRNAs are present early, whereas others are recruited much later concomitant with recruitment of translation initiation factors, such as eIF4E. We also find that Bfr1p is a late phase localizing P-body protein that is important for the delayed entry of the specific tested mRNAs to P-bodies. Therefore, for the mRNAs tested, relocalization to P-bodies varies both in terms of the kinetics and factor requirements. This work highlights a potential new regulatory juncture in gene expression that would facilitate the overall rationalization of protein content required for adaptation to stress.