The glucose-regulated nuclear localization of hexokinase 2 in Saccharomyces cerevisiae is Mig1-dependent.
Two major mediators of glucose repression in Saccharomyces cerevisiae are the proteins Mig1 and Hxk2. The mechanism of Hxk2-dependent glucose repression pathway is not well understood, but the Mig1-dependent part of the pathway has been elucidated in great detail. Here we report that Hxk2 has a glucose-regulated nuclear localization and that Mig1, a transcriptional repressor responsible for glucose repression of many genes, is required to sequester Hxk2 into the nucleus. Mig1 and Hxk2 interacted in vivo in a yeast two-hybrid assay and in vitro in immunoprecipitation and glutathione S-transferase pull-down experiments. We found that the Lys(6)-Met(15) decapeptide of Hxk2, which is necessary for nuclear localization of the protein, is also essential for interaction with the Mig1 protein. Our results also show that the Hxk2-Mig1 interaction is of physiological significance because both proteins have been found interacting together in a cluster with DNA fragments containing the MIG1 site of SUC2 promoter. We conclude that Hxk2 operates by interacting with Mig1 to generate a repressor complex located in the nucleus of S. cerevisiae during growth in glucose medium.
Ahuatzi
Deifilia
D
Departamento de Bioquímica y Biología Molecular, Universidad de Oviedo, Campus del Cristo, 33006 Oviedo, Spain.
Herrero
Pilar
P
de la Cera
Tamara
T
Moreno
Fernando
F
D002467:Cell Nucleus / Q000201:enzymology; D004268:DNA-Binding Proteins / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D005947:Glucose / Q000378:metabolism*; D006593:Hexokinase / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D014158:Transcription, Genetic / Q000502:physiology; D043324:beta-Fructofuranosidase / Q000378:metabolism
D004268:DNA-Binding Proteins; C085976:MIG1 protein, S cerevisiae; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D006593:Hexokinase; C468437:SUC2 protein, S cerevisiae; D043324:beta-Fructofuranosidase; D005947:Glucose