Translation is controlled by numerous accessory proteins and translation factors. In the yeast Saccharomyces cerevisiae, translation elongation requires an essential elongation factor, the ABCF ATPase eEF3. A closely related protein, NEW1, is encoded by a non-essential gene with cold sensitivity and ribosome assembly defect knock-out phenotypes. Since the exact molecular function of NEW1 is unknown, it is unclear if the ribosome assembly defect is direct, i.e. NEW1 is a bona fide assembly factor, or indirect, for instance due to a defect in protein synthesis. To investigate this, we employed yeast genetics, cryo-electron microscopy (cryo-EM) and ribosome profiling (Ribo-Seq) to interrogate the molecular function of NEW1. Overexpression of NEW1 rescues the inviability of a yeast strain lacking the otherwise strictly essential translation factor eEF3. The structure of the ATPase-deficient (EQ2) NEW1 mutant locked on the 80S ribosome reveals that NEW1 binds analogously to the ribosome as eEF3. Finally, Ribo-Seq analysis revealed that loss of NEW1 leads to ribosome queuing upstream of 3'-terminal lysine and arginine codons, including those genes encoding proteins of the cytoplasmic translational machinery. Our results suggest that NEW1 is a translation factor that fine-tunes the efficiency of translation termination or ribosome recycling.

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Journal Article | Research Support, Non-U.S. Gov't

Authors

Kasari V, Pochopien AA, Margus T, Murina V, Turnbull K, Zhou Y, Nissan T, Graf M, Nováček J, Atkinson GC, ... Show all

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