title: Bulk RNA degradation by nitrogen starvation-induced autophagy in yeast.
abstract: Autophagy is a catabolic process conserved among eukaryotes. Under nutrient starvation, a portion of the cytoplasm is non-selectively sequestered into autophagosomes. Consequently, ribosomes are delivered to the vacuole/lysosome for destruction, but the precise mechanism of autophagic RNA degradation and its physiological implications for cellular metabolism remain unknown. We characterized autophagy-dependent RNA catabolism using a combination of metabolome and molecular biological analyses in yeast. RNA delivered to the vacuole was processed by Rny1, a T2-type ribonuclease, generating 3'-NMPs that were immediately converted to nucleosides by the vacuolar non-specific phosphatase Pho8. In the cytoplasm, these nucleosides were broken down by the nucleosidases Pnp1 and Urh1. Most of the resultant bases were not re-assimilated, but excreted from the cell. Bulk non-selective autophagy causes drastic perturbation of metabolism, which must be minimized to maintain intracellular homeostasis.
authors.affiliation: Department of Biotechnology, Osaka University, Suita Osaka, Japan.
authors.forename: Hanghang
authors.initials: H
authors.lastname: Huang
authors.affiliation: Frontier Research Center, Tokyo Institute of Technology, Midori-ku Yokohama, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Kawamata
authors.affiliation: Frontier Research Center, Tokyo Institute of Technology, Midori-ku Yokohama, Japan.
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Horie
authors.affiliation: Department of Biotechnology, Osaka University, Suita Osaka, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tsugawa
authors.affiliation: Department of Biotechnology, Osaka University, Suita Osaka, Japan.
authors.forename: Yasumune
authors.initials: Y
authors.lastname: Nakayama
authors.affiliation: Frontier Research Center, Tokyo Institute of Technology, Midori-ku Yokohama, Japan yohsumi@iri.titech.ac.jp fukusaki@bio.eng.osaka-u.ac.jp.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Ohsumi
authors.affiliation: Department of Biotechnology, Osaka University, Suita Osaka, Japan yohsumi@iri.titech.ac.jp fukusaki@bio.eng.osaka-u.ac.jp.
authors.forename: Eiichiro
authors.initials: E
authors.lastname: Fukusaki
mesh_terms: D000469:Alkaline Phosphatase / Q000235:genetics / Q000378:metabolism; D001343:Autophagy; D000071183:Autophagy-Related Proteins; D015153:Blotting, Western; D002853:Chromatography, Liquid; D010450:Endopeptidases / Q000235:genetics / Q000378:metabolism; D013058:Mass Spectrometry; D055442:Metabolome; D008856:Microscopy, Fluorescence; D009584:Nitrogen / Q000378:metabolism*; D020871:RNA Stability; D012260:Ribonucleases / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D013217:Starvation; D014617:Vacuoles / Q000378:metabolism
chemical_list: C434064:ATG2 protein, S cerevisiae; D000071183:Autophagy-Related Proteins; D029701:Saccharomyces cerevisiae Proteins; D012260:Ribonucleases; C540806:Rny1 protein, S cerevisiae; D000469:Alkaline Phosphatase; C510355:PHO8 protein, S cerevisiae; D010450:Endopeptidases; C503886:Bre5 protein, S cerevisiae; C101111:UBP3 protein, S cerevisiae; D009584:Nitrogen
keywords: RNA degradation; autophagy; metabolome analysis; ribosome; vacuole