AUT3, a serine/threonine kinase gene, is essential for autophagocytosis in Saccharomyces cerevisiae.


Autophagocytosis is a starvation-induced process, carrying proteins destined for degradation to the lysosome. In the yeast Saccharomyces cerevisiae, the autophagic process is visualized by the appearance of autophagic vesicles in the vacuoles of proteinase yscB-deficient strains during starvation. aut3-1 mutant cells which exhibit a block in the autophagic process have been isolated previously. By using the drastically reduced sporulation frequency of homozygous aut3-1 diploid cells, the AUT3 gene was cloned by complementation. The Aut3 protein consists of 897 amino acids. The amino-terminal part of the protein shows significant homologies to serine/threonine kinases. aut3 null mutant cells are fully viable on rich media but show a reduced survival rate upon starvation. They are unable to accumulate autophagic vesicles in the vacuole during starvation. Starvation-induced vacuolar protein breakdown is almost completely impaired in aut3-deficient cells. Vacuolar morphology and acidification are not influenced in aut3-deficient cells. Also, secretion of invertase, endocytic uptake of Lucifer Yellow, and vacuolar protein sorting appear wild type like in aut3-deficient cells, suggesting autophagocytosis as a novel route for the transport of proteins from the cytosol to the vacuole. By using a fusion of Aut3p with green-fluorescent protein, Aut3p was localized to the cytosol.


Citations per Year

93 Citations

Semantic Scholar estimates that this publication has 93 citations based on the available data.

See our FAQ for additional information.

Cite this paper

@article{Straub1997AUT3AS, title={AUT3, a serine/threonine kinase gene, is essential for autophagocytosis in Saccharomyces cerevisiae.}, author={Moritz Straub and Monika Bredschneider and Michael Thumm}, journal={Journal of bacteriology}, year={1997}, volume={179 12}, pages={3875-83} }