Affiliation:
1. Faculty of Science, Swammerdam Institute for Life Science, University of Amsterdam, 1018 TV Amsterdam,1 and
2. Faculty of Biology, Department of Molecular Cell Physiology, Free University, 1081 HV Amsterdam,2 The Netherlands
Abstract
ABSTRACT
Hexokinase II is an enzyme central to glucose metabolism and glucose repression in the yeast
Saccharomyces cerevisiae
. Deletion of
HXK2
, the gene which encodes hexokinase II, dramatically changed the physiology of
S. cerevisiae
. The
hxk2
-null mutant strain displayed fully oxidative growth at high glucose concentrations in early exponential batch cultures, resulting in an initial absence of fermentative products such as ethanol, a postponed and shortened diauxic shift, and higher biomass yields. Several intracellular changes were associated with the deletion of hexokinase II. The
hxk2
mutant had a higher mitochondrial H
+
-ATPase activity and a lower pyruvate decarboxylase activity, which coincided with an intracellular accumulation of pyruvate in the
hxk2
mutant. The concentrations of adenine nucleotides, glucose-6-phosphate, and fructose-6-phosphate are comparable in the wild type and the
hxk2
mutant. In contrast, the concentration of fructose-1,6-bisphosphate, an allosteric activator of pyruvate kinase, is clearly lower in the
hxk2
mutant than in the wild type. The results suggest a redirection of carbon flux in the
hxk2
mutant to the production of biomass as a consequence of reduced glucose repression.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
62 articles.
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