title: Hap4p overexpression in glucose-grown Saccharomyces cerevisiae induces cells to enter a novel metabolic state.
abstract: BACKGROUND
  Metabolic and regulatory gene networks generally tend to be stable. However, we have recently shown that overexpression of the transcriptional activator Hap4p in yeast causes cells to move to a state characterized by increased respiratory activity. To understand why overexpression of HAP4 is able to override the signals that normally result in glucose repression of mitochondrial function, we analyzed in detail the changes that occur in these cells.
  
  
  RESULTS
  Whole-genome expression profiling and fingerprinting of the regulatory activity network show that HAP4 overexpression provokes changes that also occur during the diauxic shift. Overexpression of HAP4, however, primarily acts on mitochondrial function and biogenesis. In fact, a number of nuclear genes encoding mitochondrial proteins are induced to a greater extent than in cells that have passed through a normal diauxic shift: in addition to genes required for mitochondrial energy conservation they include genes encoding mitochondrial ribosomal proteins.
  
  
  CONCLUSIONS
  We show that overproduction of a single nuclear transcription factor enables cells to move to a novel state that displays features typical of, but clearly not identical to, other derepressed states.
authors.affiliation: Swammerdam Institute for Life Sciences, University of Amsterdam, 1098 SM Amsterdam, The Netherlands. r.lascaris@nki.nl
authors.forename: Romeo
authors.initials: R
authors.lastname: Lascaris
authors.forename: Harmen J
authors.initials: HJ
authors.lastname: Bussemaker
authors.forename: André
authors.initials: A
authors.lastname: Boorsma
authors.forename: Matt
authors.initials: M
authors.lastname: Piper
authors.forename: Hans
authors.initials: H
authors.lastname: van der Spek
authors.forename: Les
authors.initials: L
authors.lastname: Grivell
authors.forename: Jolanda
authors.initials: J
authors.lastname: Blom
mesh_terms: D023081:CCAAT-Binding Factor / Q000235:genetics* / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects / Q000235:genetics; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects; D005800:Genes, Fungal / Q000235:genetics; D005947:Glucose / Q000494:pharmacology*; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects; D015854:Up-Regulation / Q000187:drug effects; D015032:Zinc / Q000378:metabolism
chemical_list: D023081:CCAAT-Binding Factor; C061437:HAP4 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D005947:Glucose; D015032:Zinc