Not all Processing-Bodies Form Equally

Translational repression enables rapid adaptation to environmental change. During stress, translationally repressed mRNAs and mRNA decay factors accumulate in cytoplasmic processing bodies (PBs), which contribute to mRNA storage and turnover. PBs are well characterised in yeast glucose starvation, but less so under other stresses. We show that the extent of translation attenuation correlates with PB brightness, material properties, and recruitment of core components. Strong translation attenuation produces few, intense, more fluid PBs that recruit decay factors en bloc, whereas weaker attenuation yields many dimmer, more viscous PBs with sequential protein recruitment. Increasing the pool of non-translated mRNAs enhances the intensity of dim PBs and accelerates decay machinery recruitment. Consistently, elevating RNA levels enlarges Dhh1 helicase–containing droplets in vitro. We propose that non-translated mRNA abundance governs PB assembly pathways and biophysical states, thereby tuning the engagement of mRNA decay under stress.