The yeast A kinases differentially regulate iron uptake and respiratory function.
Yeast has three A kinase catalytic subunits, which have greater than 75% identity and are encoded by the TPK genes (TPK1, TPK2, and TPK3) [Toda, T., Cameron, S., Sass, P., Zoller, M. & Wigler, M. (1987) Cell 50, 277-287]. Although they are redundant for viability, the three A kinases are not redundant for pseudohyphal growth [Robertson, L. S. & Fink, G. R. (1998) Proc. Natl. Acad. Sci. USA 95, 13783-13787; Pan, X. & Heitman, J. (1999) Mol. Cell. Biol. 19, 4874-4887]; Tpk2, but not Tpk1 or Tpk3, is required for pseudohyphal growth. Genome-wide transcriptional profiling has revealed unique signatures for each of the three A kinases leading to the identification of additional functional diversity among these proteins. Tpk2 negatively regulates genes involved in iron uptake and positively regulates genes involved in trehalose degradation and water homeostasis. Tpk1 is required for the derepression of branched chain amino acid biosynthesis genes that seem to have a second role in the maintenance of iron levels and DNA stability within mitochondria. The fact that TPK2 mutants grow better than wild types on nonfermentable carbon sources and on media deficient in iron supports the unique role of Tpk2 in respiratory growth and carbon source use.
Robertson
L S
LS
Whitehead Institute for Biomedical Research, Nine Cambridge Center, Cambridge, MA, 02142, USA.
Causton
H C
HC
Young
R A
RA
Fink
G R
GR
D015072:2-Acetolactate Mutase / Q000096:biosynthesis / Q000235:genetics; D018528:ATP-Binding Cassette Transporters / Q000096:biosynthesis / Q000235:genetics; D020346:Aquaporins / Q000096:biosynthesis / Q000235:genetics; D020134:Catalytic Domain / Q000235:genetics; D003470:Culture Media; D017868:Cyclic AMP-Dependent Protein Kinases / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D000431:Ethanol / Q000378:metabolism; D005297:Ferrozine / Q000494:pharmacology; D005656:Fungal Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D020869:Gene Expression Profiling; D015966:Gene Expression Regulation, Fungal; D005990:Glycerol / Q000378:metabolism; D007501:Iron / Q000378:metabolism*; D007502:Iron Chelating Agents / Q000494:pharmacology; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D010101:Oxygen Consumption / Q000235:genetics; D010641:Phenotype; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins; D014158:Transcription, Genetic; D014198:Trehalase / Q000096:biosynthesis / Q000235:genetics
D018528:ATP-Binding Cassette Transporters; D020346:Aquaporins; D003470:Culture Media; D005656:Fungal Proteins; D007502:Iron Chelating Agents; D007527:Isoenzymes; D029701:Saccharomyces cerevisiae Proteins; C106609:YBT1 protein, S cerevisiae; D005297:Ferrozine; D000431:Ethanol; D007501:Iron; D017868:Cyclic AMP-Dependent Protein Kinases; D014198:Trehalase; D015072:2-Acetolactate Mutase; D005990:Glycerol