Roles of vacuolar proteases in the autophagic degradation of nuclei and other substrates in Aspergillus oryzae
- 1Department of Biotechnology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-Ku, Tokyo, 113-8657 Japan
- 2Collaborative Research Institute for Innovative Microbiology (CRIIM), The University of Tokyo, 1-1-1 Yayoi, Bunkyo-Ku, Tokyo, 113-8657 Japan
Abstract
Background: We previously reported that in the filamentous fungus Aspergillus oryzae entire nuclei were degraded by autophagy when cells are exposed to nutrient starvation. In this study we investigated the role of vacuolar proteases in autophagic degradation of nuclei (nucleophagy) and bulk autophagy in A. oryzae.
Methods and results: We constructed A. oryzae mutants disrupted for pepE and Aoprb1 encoding the orthologs of major vacuolar proteases Pep4 and Prb1, respectively, in Saccharomyces cerevisiae. Surprisingly, disruption of pepE did not result in any autophagy-related phenotypic alterations such as reduced conidiation and decrease in starvation-induced substrate degradation. In contrast, Aoprb1 disruptant exhibited apparently contradictory phenotypes: while conidiation was severely impaired and accumulation of autophagic bodies in the vacuoles was observed, degradation of AoAtg8 and histone H2B, markers for autophagic flux and nucleophagy, respectively, only slightly or not significantly reduced. Double disruption of pepE and Aoprb1 markedly impaired AoAtg8 degradation, whereas nucleophagy was only partially reduced.
Conclusions: These results suggest that in A. oryzae PepE does not play a major role in the autophagic processes, and that nuclear degradation requires additional protease(s) besides PepE and AoPrb1.
Supplementary Information: The online version contains supplementary material available at https://doi.org/10.1007/s11033-026-13002-3.
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BibTeX
@article{yamaguchi2026roles,
title = {{Roles of vacuolar proteases in the autophagic degradation of nuclei and other substrates in Aspergillus oryzae}},
author = {Hiroto Yamaguchi and Junka Fujita and Manabu Arioka},
journal = {Molecular Biology Reports},
year = {2026},
month = oct,
doi = {10.1007/s11033-026-13002-3},
url = {https://doi.org/10.1007/s11033-026-13002-3},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - JOUR
TI - Roles of vacuolar proteases in the autophagic degradation of nuclei and other substrates in Aspergillus oryzae
AU - Hiroto Yamaguchi
AU - Junka Fujita
AU - Manabu Arioka
PY - 2026
DA - 2026/10/25
JO - Molecular Biology Reports
DO - 10.1007/s11033-026-13002-3
UR - https://doi.org/10.1007/s11033-026-13002-3
AB - Background: We previously reported that in the filamentous fungus Aspergillus oryzae entire nuclei were degraded by autophagy when cells are exposed to nutrient starvation. In this study we investigated the role of vacuolar proteases in autophagic degradation of nuclei (nucleophagy) and bulk autophagy in A. oryzae. Methods and results: We constructed A. oryzae mutants disrupted for pepE and Aoprb1 encoding the orthologs of major vacuolar proteases Pep4 and Prb1, respectively, in Saccharomyces cerevisiae. Surprisingly, disruption of pepE did not result in any autophagy-related phenotypic alterations such as reduced conidiation and decrease in starvation-induced substrate degradation. In contrast, Aoprb1 disruptant exhibited apparently contradictory phenotypes: while conidiation was severely impaired and accumulation of autophagic bodies in the vacuoles was observed, degradation of AoAtg8 and histone H2B, markers for autophagic flux and nucleophagy, respectively, only slightly or not significantly reduced. Double disruption of pepE and Aoprb1 markedly impaired AoAtg8 degradation, whereas nucleophagy was only partially reduced. Conclusions: These results suggest that in A. oryzae PepE does not play a major role in the autophagic processes, and that nuclear degradation requires additional protease(s) besides PepE and AoPrb1. Supplementary Information: The online version contains supplementary material available at https://doi.org/10.1007/s11033-026-13002-3.
SN - 0301-4851
SN - 1573-4978
ER -