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EMBO J. 2015 Jan 13;34(2):154-68. doi: 10.15252/embj.201489083. Epub 2014 Dec 2.

Bulk RNA degradation by nitrogen starvation-induced autophagy in yeast.

Author information

1
Department of Biotechnology, Osaka University, Suita Osaka, Japan.
2
Frontier Research Center, Tokyo Institute of Technology, Midori-ku Yokohama, Japan.
3
Frontier Research Center, Tokyo Institute of Technology, Midori-ku Yokohama, Japan yohsumi@iri.titech.ac.jp fukusaki@bio.eng.osaka-u.ac.jp.
4
Department of Biotechnology, Osaka University, Suita Osaka, Japan yohsumi@iri.titech.ac.jp fukusaki@bio.eng.osaka-u.ac.jp.

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.

KEYWORDS:

RNA degradation; autophagy; metabolome analysis; ribosome; vacuole

PMID:
25468960
PMCID:
PMC4337068
DOI:
10.15252/embj.201489083
[Indexed for MEDLINE]
Free PMC Article

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