Autophagy mediates nonselective RNA degradation in starving yeast

Abstract

During nitrogen starvation, a nonselective bulk degradation of cytosolic proteins and organelles including ribosomes, termed macro‐autophagy (hereafter termed autophagy), is induced. The precise mechanism of RNA degradation by this pathway has not been yet elucidated. In this issue of the The EMBO Journal, Huang et al characterize an autophagy‐dependent RNA catabolism in yeast and identify the enzymes responsible for the degradation process.

Figure 1. Autophagy-dependent RNA degradation under nitrogen starvation

Upon nitrogen starvation, RNA is engulfed by a phagophore and transported into the vacuole by the resulting autophagosome (A). The released RNA is then processed by Rny1 to nucleotides (3′-NMPs) (B), which are further catabolized by Pho8 to form nucleosides (C). The generated nucleosides are transported from the vacuole to the cytosol, where they are processed by Pnp1 and Urh1 to nucleobases, which are then excreted from the cell (D).