Deficiency of
PKC1 activity affects glycerol metabolism in Saccharomyces cerevisiae.
Rogelio L. Brandão,
Luciano G. Fietto, Kátia N. Gomes, Ieso M. Castro, Suzy M. A. C. Freitas,
Thiago M. Pais
DEFAR/EF/NUPEB, Federal University Ouro Preto, Campus M. Cruzeiro, Ouro Preto,
MG 35.400-000, Brazil (rlbrand@nupeb.ufop.br)
Originally, protein kinase C was described as a regulator of a MAP kinase cascade controlling cell integrity. We have demonstrated that Pkc1 plays a role in carbon metabolism independent of the MAP kinase cascade controlling cell integrity. Pkc1 appears to be involved in controlling the response to glucose during the initiation of fermentative growth and it affects the expression of glucose transporter genes (Brandão et al, 2002 Fems Yeast Research, 2 (2): 93-102. Our results suggest an involvement of Pkc1p in the control of glycerol metabolism which is not shared by the downstream MAP kinase cascade. A yeast strain with a deletion of the PKC1 gene is unable to grow on glycerol as sole carbon source. We demonstrate that pkc1 mutants are deficient in glycerol kinase activity due to a problem in the GUT1 expression. We demonstrated that Pkc1p is important for the control of the cellular localization of the Mig1 transcription factor (Salgado et al., 2002 FEBS Letters 532 324-332). Therefore we suppose that Pkc1p could regulate the cellular localization of Adr1 a transcription factor that acts at an upstream activating sequence (UAS) on the GUT1 gene. We also isolated a new mutant that recovered the normal growth on glycerol. From this strain, we were able to isolate two transformants that recovered the original phenotype of pkc1 mutant. By this way, two extragenic suppressors of this mutation were identified: the Nuclear Exportin Msn5 and the Histone Deacetylase Hos2.