The mitochondrial phosphatidylserine decarboxylase Psd1 is involved in nitrogen starvation-induced mitophagy in yeast
Pierre Vigié 1,2, Elodie Cougouilles1,2, Ingrid Bhatia-Kiššová 3 , Bénédicte Salin1,2, Corinne Blancard1,2 and Nadine Camougrand1,2,*Link to the original article
Year of publication
J Cell Science
1 CNRS, UMR5095, 1 rue Camille Saint-Saëns, 33077 Bordeaux, France. 2 Université de Bordeaux, UMR5095, 1 rue Camille Saint-Saëns, 33077 Bordeaux,France. 3 Comenius University, Faculty of Natural Sciences, Department of Biochemistry, Mlynská dolina CH1, 84215 Bratislava, Slovak Republic.
Mitophagy allows the selective degradation, by an autophagic process, of healthy or damaged mitochondria depending on the physiological state of the cells. In this work, we investigated the involvement of different pools of phosphatidyl ethanolamine (PE) in the induction of autophagy and mitophagy—either into nitrogen starvation or into the stationary growth phase. Indeed, PE plays an important role in these processes because it conjugates with the Atg8 protein on the side of the Cterminal end. Thus, the lipidated Atg8 protein is inserted into the membranes of autophagosomes. In yeast, several routes of PE synthesis have been characterized. With regard to mitophagy, our results showed that the enzyme Psd2, located in the Golgi and vacuolar membranes, is one of the major sources of PE in the stationary phase of growth. However, during nitrogen starvation, the enzyme Psd1 that produces PE in the mitochondria is required for mitophagy. By employing different approaches, we have shown that the Atg8, Atg4, and Atg3 proteins are localized to mitochondria during nitrogen starvation. We hypothesized that in this condition, mitochondria provide PE for the phagophore membranes or for conjugation with the Atg8 protein, which are two essential steps of mitophagy process. In addition, contact between mitochondria and the vacuole has been observed during the first hours of nitrogen starvation. This could suggest a direct sequestration of mitochondria by the vacuole and the need for proximity among PAS, mitochondria, and vacuole. The importance of enzymes feeding the pool of PE required for mitophagy differs depending on the conditions of mitophagy induction. Thus, the sequestration of mitochondria could be executed by various mechanisms and controlled by several signaling pathways