The Observation of Saccharomyces cerevisiae infrastructure Changes under Proline Limitation
Microscopy and Microanalysis
Proline is an important amino acid, which involves in not only protein synthesis, but also in various stress response in many organisms  . It was suggested that increase of intracellular proline level protects plants or yeast cell against stress via improvement vacuole biogenesis since vacuole is an important compartment for cell survive under various stress  . Autophagy is a conserved cellular process that mediates protein degradation in lysosomes called vacuoles in yeast  . It plays
... ast  . It plays an important role in resource energy when cells undergoing nutrient starvation. Nitrogen starvation is a common used assay to test whether or not cells bear functional autophagy to nutrient starvation. Here we report the proline biosynthesis gene PRO3 null mutant of Saccharomyces cerevisiae BY4741 is hyper sensitive to nitrogen starvation, the survive rate under nitrogen starvation is similar to that of atg8 mutant strain in which autophagy is deficient. However other amino acid starvation such as leucine, histidine doses not affect yeast cells survive under shortage of nitrogen source. The autophagy bodies were further examined using transmission electron microscope. While growing in minimal medium without nitrogen for 4 hours, similar to atg8 mutant, the yeast cells of pro3 strain showed significant fewer autophagy bodies compared with wild-type and pep4 mutant. Our data suggests that proline may play an important role in autophagy formation.