Article abstract
Nature Chemical Biology 4, 602 - 608 (2008)
Published online: 24 August 2008 | doi:10.1038/nchembio.108
A domino effect in antifolate drug action in Escherichia coli
Yun Kyung Kwon1, Wenyun Lu1, Eugene Melamud1, Nurussaba Khanam2, Andrew Bognar2 & Joshua D Rabinowitz1
Abstract
Mass spectrometry technologies for measurement of cellular metabolism are opening new avenues to explore drug activity. Trimethoprim is an antibiotic that inhibits bacterial dihydrofolate reductase (DHFR). Kinetic flux profiling with 15N-labeled ammonia in Escherichia coli reveals that trimethoprim leads to blockade not only of DHFR but also of another critical enzyme of folate metabolism: folylpoly-
-glutamate synthetase (FP-
-GS). Inhibition of FP-
-GS is not directly due to trimethoprim. Instead, it arises from accumulation of DHFR's substrate dihydrofolate, which we show is a potent FP-
-GS inhibitor. Thus, owing to the inherent connectivity of the metabolic network, falling DHFR activity leads to falling FP-
-GS activity in a domino-like cascade. This cascade results in complex folate dynamics, and its incorporation in a computational model of folate metabolism recapitulates the dynamics observed experimentally. These results highlight the potential for quantitative analysis of cellular metabolism to reveal mechanisms of drug action.
- Department of Chemistry and Lewis-Sigler Institute for Integrative Genomics, Carl Icahn Laboratory, Princeton University, Washington Road, Princeton, New Jersey 08544, USA.
- Department of Microbiology, Medical Sciences Building #4383, University of Toronto, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada.
Correspondence to: Joshua D Rabinowitz1 e-mail: joshr@genomics.princeton.edu
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