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The Saccharomyces cerevisiae zinc factor protein Stb5p is required as a basal regulator of the pentose phosphate pathway
Author(s) -
Cadière Axelle,
Galeote Virginie,
Dequin Sylvie
Publication year - 2010
Publication title -
fems yeast research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.991
H-Index - 92
eISSN - 1567-1364
pISSN - 1567-1356
DOI - 10.1111/j.1567-1364.2010.00672.x
Subject(s) - pentose phosphate pathway , biology , overproduction , biochemistry , auxotrophy , saccharomyces cerevisiae , mutant , metabolism , yeast , gene , glycolysis
In Saccharomyces cerevisiae , the oxidative stress‐activated zinc cluster protein Stb5p activates genes involved in NADPH production and most genes of the pentose phosphate (PP) pathway. To gain insight into the role of Stb5p, we studied the behaviour of stb5 deletion mutants during aerobic and anaerobic growth on glucose. stb5 mutants were auxotrophic for methionine and pyrimidine nucleotides. The methionine auxotrophy phenotype was air dependent, suggesting an impaired aerobic NADPH status. Consistent with this, the acetate level was reduced and the α‐ketoglutarate level was increased in the stb5 mutant. stb5 cells also required pyrimidine nucleotides for aerobic and anaerobic growth, consistent with a reduction in 5‐phosphoribosyl‐1‐pyrophosphate production caused by a reduced flux through the PP pathway. Strains overexpressing STB5 could not grow on glucose. This growth defect was restored by overproduction of an NADPH‐butanediol dehydrogenase, which reoxidizes the excess NADPH in the oxidative PP pathway. These findings suggest a major role for the transcription factor Stb5p in maintaining a basal flux through the PP pathway to meet the NADPH requirements for aerobic growth, and to provide the nucleotide precursors. Our data also demonstrate the potential use of a system based on overproduction of this transcription factor to increase flux through the PP pathway.

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