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Molecular and Cellular Biology, May 2000, p. 2984-2995, Vol. 20, No. 9
SFB Biomembrane Research Center, Institut
für Biochemie und Lebensmittelchemie, Technische
Universität Graz,1 and Institut
für Pflanzenphysiologie, Karl-Franzens
Universität,3 A-8010 Graz, Austria, and
Department of Biochemistry, New York University Medical Center,
New York, New York 100162
Received 14 September 1999/Returned for modification 19 November
1999/Accepted 2 February 2000
The yeast vacuole functions both as a degradative organelle and as
a storage depot for small molecules and ions. Vacuoles are dynamic
reticular structures that appear to alternately fuse and fragment as a
function of growth stage and environment. Vac8p, an armadillo
repeat-containing protein, has previously been shown to function both
in vacuolar inheritance and in protein targeting from the cytoplasm to
the vacuole. Both myristoylation and palmitoylation of Vac8p are
required for its efficient localization to the vacuolar membrane (Y.-X.
Wang, N. L. Catlett, and L. S. Weisman, J. Cell Biol.
140:1063-1074, 1998). We report that mutants with conditional defects
in the rate-limiting enzyme of fatty acid synthesis, acetyl coenzyme A
carboxylase (ACC1), display unusually multilobed vacuoles, similar to those observed in vac8 mutant cells. This
vacuolar phenotype of acc1 mutant cells was shown
biochemically to be accompanied by a reduced acylation of Vac8p which
was alleviated by fatty acid supplementation. Consistent with the
proposed defect of acc1 mutant cells in acylation of Vac8p,
vacuolar membrane localization of Vac8p was impaired upon shifting
acc1 mutant cells to nonpermissive condition. The function
of Vac8p in protein targeting, on the other hand, was not affected
under these conditions. These observations link fatty acid synthesis
and availability to direct morphological alterations of an organellar membrane.
0270-7306/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
A Novel Cold-Sensitive Allele of the Rate-Limiting
Enzyme of Fatty Acid Synthesis, Acetyl Coenzyme A Carboxylase,
Affects the Morphology of the Yeast Vacuole through Acylation
of Vac8p

*
Corresponding author. Mailing address: Institut
für Biochemie und Lebensmittelchemie, Technische
Universität Graz, Petersgasse 12, A-8010 Graz, Austria. Phone:
43-316-873-6955. Fax: 43-316-873-6952. E-mail:
f548roge{at}mbox.tu-graz.ac.at.
Present address: Department of Microbiology and Molecular Genetics,
UMDNJ-New Jersey Medical School, Newark, NJ 07103.
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