Mutations in SIN4 and RGR1 cause constitutive expression of MAL structural genes in Saccharomyces cerevisiae.
Transcription of the Saccharomyces MAL structural genes is induced 40-fold by maltose and requires the MAL-activator and maltose permease. To identify additional players involved in regulating MAL gene expression, we carried out a genetic selection for MAL constitutive mutants. Strain CMY4000 containing MAL1 and integrated copies of MAL61promoter-HIS3 and MAL61promoter-lacZ reporter genes was used to select constitutive mutants. The 29 recessive mutants fall into at least three complementation groups. Group 1 and group 2 mutants exhibit pleiotropic phenotypes and represent alleles of Mediator component genes RGR1 and SIN4, respectively. The rgr1 and sin4 constitutive phenotype does not require either the MAL-activator or maltose permease, indicating that Mediator represses MAL basal expression. Further genetic analysis demonstrates that RGR1 and SIN4 work in a common pathway and each component of the Mediator Sin4 module plays a distinct role in regulating MAL gene expression. Additionally, the Swi/Snf chromatin-remodeling complex is required for full induction, suggesting a role for chromatin remodeling in the regulation of MAL gene expression. A sin4Delta mutation is unable to suppress the defects in MAL gene expression resulting from loss of the Swi/Snf complex component Snf2p. The role of the Mediator in MAL gene regulation is discussed.
Wang
Xin
X
Department of Biology, Queens College and the Graduate School of City University of New York, Flushing, New York 11367, USA.
Michels
Corinne A
CA
D042002:Chromatin Assembly and Disassembly; D015966:Gene Expression Regulation, Fungal; D007763:Lac Operon; D008320:Maltose / Q000378:metabolism; D056892:Mediator Complex; D026901:Membrane Transport Proteins / Q000235:genetics; D009004:Monosaccharide Transport Proteins / Q000235:genetics* / Q000378:metabolism; D009154:Mutation / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism; D027981:Symporters / Q000235:genetics* / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D000520:alpha-Glucosidases / Q000235:genetics
D056892:Mediator Complex; D026901:Membrane Transport Proteins; D009004:Monosaccharide Transport Proteins; C095061:RGR1 protein, S cerevisiae; D012097:Repressor Proteins; C076878:SIN4 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D027981:Symporters; D015534:Trans-Activators; D014157:Transcription Factors; C067575:maltose transport system, S cerevisiae; D008320:Maltose; C021534:maltose permease; D000520:alpha-Glucosidases