Identification of a conserved receptor for degrading ribosomes through autophagy.

Abstract

Ribosomes consist of approximately 80 distinct ribosomal proteins and rRNA. The genes encoding these ribosomal components are among the most highly expressed in growing cells. Changes in ribosome composition, such as those induced by oxidative stress, may compromise ribosome function. Such ribosomes are subsequently targeted for degradation. Additionally, under stress, both protein synthesis and ribosome biogenesis are downregulated. Under starvation stress, excess ribosomes are degraded through a process called ribophagy, a selective form of macroautophagy/autophagy that utilizes the autophagy pathway. While receptors for several selective autophagy pathways are known, the evolutionarily conserved ribophagy receptor was not identified until recently. In a recent publication, the authors identify Rpl12 and its homologs as receptors that promotes ribophagy from yeast to humans. They also demonstrate that ribophagy enhances lifespan and facilitates the clearance of pathogenic bacteria.