Is the Rsp5 ubiquitin ligase involved in the regulation of ribophagy?

• Published in: Autophagy Vol. 4; no. 6; pp. 838 - 840
• Main Authors: Kraft, Claudine, Peter, Matthias
• Format: Journal Article
• Language: English
• Published: United States Taylor & Francis 16.08.2008
• Subjects: Autophagy - physiology; Binding; Biology; Bioscience; Calcium; Cancer; Cell; Cycle; Endopeptidases - metabolism; Endosomal Sorting Complexes Required for Transport; Landes; Organogenesis; Proteins; Ribosomes - metabolism; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - metabolism; Signal Transduction - physiology; Ubiquitin - metabolism; Ubiquitin-Protein Ligase Complexes - genetics; Ubiquitin-Protein Ligase Complexes - metabolism
• ISSN: 1554-8627; 1554-8635; 1554-8635
• DOI: 10.4161/auto.6603

Under nutrient limiting conditions, cytoplasmic components are randomly sequestered into double-membrane vesicles called autophagosomes and delivered to the lysosome/vacuole for degradation and recycling. In the last few years, however, it has been observed that several cytoplasmic components such as organelles, pathogens or specific protein complexes can also be selectively targeted for degradation by autophagy-related pathways (reviewed in reference 1). We have recently shown that in S. cerevisiae, mature ribosomes are subject to such selective degradation by autophagy under starvation conditions, in a process that we termed 'ribophagy'. 2 By genetic screening, we found that selective degradation of 60S large ribosomal subunits depends on the ubiquitin protease Ubp3 and its cofactor Bre5, implying that ribophagy is regulated by ubiquitin-dependent steps. Interestingly, several ubiquitinated proteins accumulate in ribosome fractions isolated from ubp3∆ cells, suggesting that the regulation of ribophagy by ubiquitin may be direct. Here we present data on a potential role of the ubiquitin ligase Rsp5 as a positive regulator of ribophagy, and discuss the possible involvement of ubiquitin as a signaling molecule in this process. Addendum to: Kraft C, Deplazes A, Sohrmann M, Peter M. Mature ribosomes are selectively degraded upon starvation by an autophagy pathway requiring the Ubp3p/Bre5p ubiquitin protease. Nat Cell Biol 2008; 10:602-10.