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Retrograde signaling in glutamate dehydrogenase mutants of yeast
Author(s) -
Trotter Pamela J.,
Hutchison Justin,
Logsdon Mallory,
Schmitt Holly
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a663-d
Subject(s) - glutamate dehydrogenase , biochemistry , saccharomyces cerevisiae , mutant , yeast , glutamate receptor , wild type , nad+ kinase , chemistry , alcohol dehydrogenase , oleic acid , biology , enzyme , gene , receptor
Saccharomyces cerevisiae has three glutamate dehydrogenase enzymes encoded by the GDH1 and GDH3 (NADP + ‐dependent) and GDH2 (NAD + ‐dependent) genes. NADP + ‐dependent GDH activity in glucose‐grown gdh1 Δ cells is <5% as compared to wild type, while activity in gdh3 Δ and gdh2 Δ cells is comparable to wild type. Yet, strains carrying single disruptions in the GDH genes show no clear requirement for glutamate. Cells were tested for growth on glucose, ethanol, acetate or oleic acid as sole carbon source in synthetic complete medium; only gdh1 Δ strains show any impairment, unable to grow on ethanol, acetate and oleic acid. Retrograde signaling (RTG) is a pathway activated in response to decreased cellular glutamate levels due to mitochondrial dysfunction. The sensitivity of this pathway to glutamate homeostasis in glutamate dehydrogenase mutants was examined. A reporter plasmid with a promoter sensitive to RTG signaling (the CIT2 gene) fused to the lacZ gene was used to observe activity of the pathway. Strains carrying gdh2 Δ or gdh3 Δ disruptions showed activity comparable to wild type cells. In contrast, RTG activity in gdh1 Δ cells is elevated 6‐fold as compared to wild type cells, and is comparable to respiratory deficient rho ° cells. These data support the primacy of Gdh1p in glutamate homeostasis on fermentable and non‐fermentable carbon sources.