Circadian clock control of ribosome composition promotes rhythmic translation and termination fidelity [Ribo-Seq]

Ribosome composition can vary depending on cell type, stress or developmental state. Here we describe circadian clock-dependent changes in ribosome composition in Neurospora crassa. Mass spectrometry of ribosomes isolated at different circadian times identified six ribosomal proteins and one ribosome-associated protein with clock-controlled abundance. We confirmed clock control of eL31-HA abundance in purified ribosomes and found that deletion of eL31 altered translation of many mRNAs and inhibited translation rhythms for 42% of rhythmically translated mRNAs. Because eL31 homologs promote translation termination fidelity, we examined ribosome protected footprint (RPF)-seq reads mapping past stop codons over circadian time to reveal clock-dependent and eL31-enhanced rhythms in translation termination fidelity. We further discovered that eL31 promotes proper ion homeostasis and translation elongation fidelity. Taken together these studies demonstrated that the circadian clock governs daily changes in ribosome composition that control rhythms in translation and impact translation fidelity, likely through changes in intracellular Mg2+ levels. Overall design: Ribosome protected footprint (RPF)-seq of Neurospora crassa ?eL31(?ncu08344) mycelia, grown over a circadian time course, 10 time points, 2 replicate experiments for a total of 20 samples