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Molecular and Cellular Biology, December 1998, p. 7064-7074, Vol. 18, No. 12
Department of Biochemistry and Molecular
Biology, SUNY Health Science Center at Syracuse, Syracuse, New York
13210
Received 12 May 1998/Returned for modification 29 June
1998/Accepted 2 September 1998
The yeast vacuolar H+-ATPase (V-ATPase) is a
multisubunit complex responsible for organelle acidification. The
enzyme is structurally organized into two major domains: a peripheral
domain (V1), containing the ATP binding sites, and an
integral membrane domain (V0), forming the proton pore.
Dissociation of the V1 and V0 domains inhibits ATP-driven proton pumping, and extracellular glucose concentrations regulate V-ATPase activity in vivo by regulating the extent of association between the V1 and V0 domains. To
examine the mechanism of this response, we quantitated the extent of
V-ATPase assembly in a variety of mutants with known effects on other
glucose-responsive processes. Glucose effects on V-ATPase assembly did
not involve the Ras-cyclic AMP pathway, Snf1p, protein kinase C, or the
general stress response protein Rts1p. Accumulation of glucose
6-phosphate was insufficient to maintain or induce assembly of the
V-ATPase, suggesting that further glucose metabolism is required. A
transient decrease in ATP concentration with glucose deprivation occurs quickly enough to help trigger disassembly of the V-ATPase, but increases in cellular ATP concentrations with glucose readdition cannot
account for reassembly. Disassembly was inhibited in two mutant enzymes
lacking ATPase and proton pumping activities or in the presence of the
specific V-ATPase inhibitor, concanamycin A. We propose that glucose
effects on V-ATPase assembly occur by a novel mechanism that requires
glucose metabolism beyond formation of glucose 6-phosphate and
generates a signal that can be sensed efficiently only by a
catalytically competent V-ATPase.
0270-7306/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Reversible Association between the V1
and V0 Domains of Yeast Vacuolar H+-ATPase Is
an Unconventional Glucose-Induced Effect
*
Corresponding author. Mailing address: Dept. of
Biochemistry and Molecular Biology, SUNY Health Science Center at
Syracuse, 750 E. Adams St., Syracuse, NY 13210. Phone: (315) 464-8742. Fax: (315) 464-8750. E-mail:
kanepm{at}vax.cs.hscsyr.edu.
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