Current Genetics

, Volume 49, Issue 1, pp 1–6 | Cite as

Increased phosphoglucomutase activity suppresses the galactose growth defect associated with elevated levels of Ras signaling in S. cerevisiae

  • Susie C. Howard
  • Stephen J. Deminoff
  • Paul K. Herman
Research Article


The Ras proteins regulate many aspects of cell growth in the budding yeast, Saccharomyces cerevisiae, via the cAMP-dependent protein kinase (PKA). Here, we show that a RAS2val19 mutant that exhibits elevated levels of Ras/PKA signaling activity is unable to grow on media with galactose as the sole source of carbon. This growth defect was due, at least in part, to a defect in the expression of genes, like GAL1, that encode enzymes needed for the metabolism of galactose. This growth defect was used as the basis for a genetic screen for dosage suppressors of the RAS2val19 mutant. This screen identified two genes, PGM1 and PCM1, that encode proteins with phosphoglucomutase activity. This activity is responsible for converting the glucose-1-phosphate produced during the metabolism of galactose to glucose-6-phosphate, a precursor that can be metabolized via the glycolytic pathway. The over-expression of PGM1 was not able to suppress any other RAS2val19 phenotype or the galactose growth defect associated with a gal1Δ mutant. Overall, these data suggest that the elevated levels of phosphoglucomutase activity allow for the more efficient utilization of the limiting levels of glucose-1-phosphate that are present in the RAS2val19 mutant.


Ras proteins cAMP-dependent protein kinase Phosphoglucomutase PGM1 Phosphoacetylglucosamine mutase 



We thank David Bedwell for the PGM2 plasmid, David Aiello and David Bedwell for the assistance with the glucose-6-phosphate assays, Ruma Pengal for technical assistance and Joseph Stephan for comments on the manuscript. This work was supported by a grant from the National Institutes of Health (GM65227) to P.K.H.


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Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  • Susie C. Howard
    • 1
  • Stephen J. Deminoff
    • 1
  • Paul K. Herman
    • 1
  1. 1.Department of Molecular GeneticsThe Ohio State UniversityColumbusUSA

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