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Effects of mitochondrial transport protein mutations on retrograde signaling
Author(s) -
Carter Bradley S.,
TawiahBoateng MaryAnne,
Trotter Pamela J.
Publication year - 2006
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.20.5.a956
Subject(s) - mutant , mitochondrion , retrograde signaling , transporter , cytosol , microbiology and biotechnology , biochemistry , gene , biology , citric acid cycle , saccharomyces cerevisiae , chemistry , metabolism , enzyme
Efficient glutamate biosynthesis is dependent on movement of α‐ketoglutarate created in the citric acid cycle from the mitochondria to the cytosol. The subcellular distribution of α‐ketoglutarate in Saccharomyces cerevisiae with mutations in mitochondrial transporters suspected of carrying α‐ketoglutarate was investigated. The genes for four transporters ( ODC1 , ODC2 , YMC1 , YMC2 ) were disrupted to create a double mutant strain ( odc1 Δ, odc2 Δ) and a quad mutant strain ( odc1 Δ, odc2 Δ, ymc1 Δ , ymc2 Δ). Evidence of α‐ketoglutarate accumulation in the mitochondria in mutants compared to the wild type supports involvement of these transporters in α‐ketoglutarate movement. Retrograde signaling (RTG) is a pathway activated in response to decreased cellular glutamate levels due to mitochondrial dysfunction. Since inhibition of these transporters impairs glutamate synthesis, we hypothesized that RTG activity should be increased in the mutants. A gene targeted by the RTG pathway is the CIT2 gene, which encodes peroxisomal citrate synthase. A construct with the CIT2 promoter fused to the lacZ gene was used to observe changes in RTG activity. The double mutant showed increased RTG signaling as compared to wild type. The quad mutant did not show increased RTG signaling under the same conditions. Further studies will explore this unexpected occurrence. This work was funded by NIH grant GM069372 (to P.J.T.).