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J. Biol. Chem., Vol. 283, Issue 35, 23524-23532, August 29, 2008

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Quantitative Analysis of the High Temperature-induced Glycolytic Flux Increase in Saccharomyces cerevisiae Reveals Dominant Metabolic Regulation^*

Jarne Postmus, André B. Canelas, Jildau Bouwman^¶, Barbara M. Bakker^¶, Walter van Gulik, M. Joost Teixeira de Mattos^||, Stanley Brul, and Gertien J. Smits¹

From the Department of Molecular Biology and Microbial Food Safety, University of Amsterdam, Nieuwe Achtergracht 166, 1018 WV Amsterdam, Kluyver Laboratory for Biotechnology, Julianalaan 67, 2628 BC Delft, the ^¶Department of Molecular Cell Physiology, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam, and the ^||Department of Molecular Microbial Physiology, University of Amsterdam, Nieuwe Achtergracht 166, 1018 WV Amsterdam, The Netherlands

A major challenge in systems biology lies in the integration of processes occurring at different levels, such as transcription, translation, and metabolism, to understand the functioning of a living cell in its environment. We studied the high temperature-induced glycolytic flux increase in Saccharomyces cerevisiae and investigated the regulatory mechanisms underlying this increase. We used glucose-limited chemostat cultures to separate regulatory effects of temperature from effects on growth rate. Growth at increased temperature (38 °C versus 30 °C) resulted in a strongly increased glycolytic flux, accompanied by a switch from respiration to a partially fermentative metabolism. We observed an increased flux through all enzymes, ranging from 5- to 10-fold. We quantified the contributions of direct temperature effects on enzyme activities, the gene expression cascade and shifts in the metabolic network, to the increased flux through each enzyme. To do this we adapted flux regulation analysis. We show that the direct effect of temperature on enzyme kinetics can be included as a separate term. Together with hierarchical regulation and metabolic regulation, this term explains the total flux change between two steady states. Surprisingly, the effect of the cultivation temperature on enzyme catalytic capacity, both directly through the Arrhenius effect and indirectly through adapted gene expression, is only a moderate contribution to the increased glycolytic flux for most enzymes. The changes in flux are therefore largely caused by changes in the interaction of the enzymes with substrates, products, and effectors.

Received for publication, April 15, 2008 , and in revised form, May 27, 2008.

^* This work was supported by SenterNovem through the IOP Genomics Initiative, Project IGE3006A. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

The on-line version of this article (available at http://www.jbc.org) contains supplemental Table 1.

¹ To whom correspondence should be addressed. Tel.: 31-20-525-5143; Fax: 31-20-525-7924; E-mail: gertien{at}science.uva.nl.

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