Not4 and Not5 modulate translation elongation by Rps7A ubiquitination, Rli1 moonlighting, and condensates that exclude eIF5A

In this work, we show that Not4 and Not5 from the Ccr4-Not complex modulate translation elongation dynamics and change ribosome A-site dwelling occupancy in a codon-dependent fashion. These codon-specific changes in not5Δ cells are very robust and independent of codon position within the mRNA, the overall mRNA codon composition, or changes of mRNA expression levels. They inversely correlate with codon-specific changes in cells depleted for eIF5A and positively correlate with those in cells depleted for ribosome-recycling factor Rli1. Not5 resides in punctate loci, co-purifies with ribosomes and Rli1, but not with eIF5A, and limits mRNA solubility. Overexpression of wild-type or non-complementing Rli1 and loss of Rps7A ubiquitination enable Not4 E3 ligase-dependent translation of polyarginine stretches. We propose that Not4 and Not5 modulate translation elongation dynamics to produce a soluble proteome by Rps7A ubiquitination, dynamic condensates that limit mRNA solubility and exclude eIF5A, and a moonlighting function of Rli1. [Display omitted] •Not subunits of the Ccr4-Not complex form dynamic condensates excluding eIF5A•In notΔ cells, ribosome dwelling occupancies change according to codon optimality•Ribosome dwelling inversely changes upon eIF5A depletion and Not deletion•Rli1 moonlighting and Rps7A ubiquitination contribute to Not regulation Allen et al. show that codon-specific translation elongation dynamics are modulated by Not4 and Not5, in coordination with Rli1 and opposing eIF5A function, and according to codon optimality to produce a soluble proteome. We propose that this regulation occurs by dynamic condensates that limit mRNA solubility and exclude eIF5A.