期刊
JOURNAL OF BIOLOGICAL CHEMISTRY
卷 291, 期 7, 页码 3239-3253出版社
ELSEVIER
DOI: 10.1074/jbc.M115.699124
关键词
autophagy; deubiquitylation (deubiquitination); proteasome; protein translocation; vacuole; yeast; nitrogen starvation; proteaphagy; ribophagy
资金
- National Institutes of Health from NIGMS [1R15GM112142-01A1]
- National Institutes of Health [P20 GM103418]
- Johnson Cancer Research Center
The proteasome is responsible for the degradation of many cellular proteins. If and how this abundant and normally stable complex is degraded by cells is largely unknown. Here we show that in yeast, upon nitrogen starvation, proteasomes are targeted for vacuolar degradation through autophagy. Using GFP-tagged proteasome subunits, we observed that autophagy of a core particle (CP) subunit depends on the deubiquitinating enzyme Ubp3, although a regulatory particle (RP) subunit does not. Furthermore, upon blocking of autophagy, RP remained largely nuclear, although CP largely localized to the cytosol as well as granular structures within the cytosol. In all, our data reveal a regulated process for the removal of proteasomes upon nitrogen starvation. This process involves CP and RP dissociation, nuclear export, and independent vacuolar targeting of CP and RP. Thus, in addition to the well characterized transcriptional up-regulation of genes encoding proteasome subunits, cells are also capable of down-regulating cellular levels of proteasomes through proteaphagy.
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