Mitophagy in Yeast

Mitochondria play a crucial role in energy production, general cell metabolism, cell signaling, and apoptosis. Mitochondria are also the main source of reactive oxygen species, especially in the case of their dysfunction. Therefore, damaged or even superfluous mitochondria not required for normal cell functioning represent risk factors and should be removed in order to maintain cell homeostasis. Mitochondria removal occurs via mitophagy, a type of selective autophagy (from Greek autos, self and phagein, to eat) that takes place in parallel with mitochondrial biogenesis and other processes. This review outlines general views on autophagy and mitophagy and summarizes information on the autophagy-related (Atg) proteins and their complexes involved in these processes. Yeast, especially Saccharomyces cerevisiae, is a convenient model system for studying molecular mechanisms of mitophagy because yeast genome, transcriptome, and proteome have been well characterized and because genetic manipulations with yeast are relatively simple and fast. Furthermore, yeast contain a number of orthologs of human proteins. Mitophagy in yeast is promoted by various factors, such as starvation, aging, oxidative stress, mitochondrial dysfunction, signaling proteins, and modification of mitochondrial proteins. In this review, we discuss molecular mechanisms underlying mitophagy and its regulation in yeast and present examples of relationships between mitophagy and ubiquitination-deubiquitination processes, as well as between mitophagy and other types of autophagy.