Previous Article | Next Article ![]()
J. Bacteriol., 06 1997, 3875-3883, Vol 179, No. 12
M Straub, M Bredschneider and M Thumm
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.
Copyright © 1997, American Society for Microbiology
AUT3, a serine/threonine kinase gene, is essential for autophagocytosis in Saccharomyces cerevisiae
Institute fur Biochemie, Universitat Stuttgart, Germany.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»