The E2 ubiquitin conjugase Rad6 is required for the ArgR/Mcm1 repression of ARG1 transcription.
Transcription of the Saccharomyces cerevisiae ARG1 gene is under the control of both positive and negative elements. Activation of the gene in minimal medium is induced by Gcn4. Repression occurs in the presence of arginine and requires the ArgR/Mcm1 complex that binds to two upstream arginine control (ARC) elements. With the recent finding that the E2 ubiquitin conjugase Rad6 modifies histone H2B, we examined the role of Rad6 in the regulation of ARG1 transcription. We find that Rad6 is required for repression of ARG1 in rich medium, with expression increased approximately 10-fold in a rad6 null background. Chromatin immunoprecipitation analysis indicates increased binding of TATA-binding protein in the absence of Rad6. The active-site cysteine of Rad6 is required for repression, implicating ubiquitination in the process. The effects of Rad6 at ARG1 involve two components. In one of these, histone H2B is the likely target for ubiquitination by Rad6, since a strain expressing histone H2B with the principal ubiquitination site converted from lysine to arginine shows a fivefold relief of repression. The second component requires Ubr1 and thus likely the pathway of N-end rule degradation. Through the analysis of promoter constructs with ARC deleted and an arg80 rad6 double mutant, we show that Rad6 repression is mediated through the ArgR/Mcm1 complex. In addition, analysis of an ada2 rad6 deletion strain indicated that the SAGA acetyltransferase complex and Rad6 act in the same pathway to repress ARG1 in rich medium.
Turner
Suzanne D
SD
Department of Biochemistry, University of Western Ontario, London, Canada N6A 5C1.
Ricci
Andrea R
AR
Petropoulos
Helen
H
Genereaux
Julie
J
Skerjanc
Ilona S
IS
Brandl
Christopher J
CJ
D001120:Arginine; D001124:Argininosuccinate Synthase / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D003470:Culture Media; D004268:DNA-Binding Proteins; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D006657:Histones / Q000235:genetics / Q000378:metabolism; D008025:Ligases / Q000235:genetics / Q000378:metabolism*; D026341:Minichromosome Maintenance 1 Protein / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D017853:Phosphotransferases (Alcohol Group Acceptor); D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D044763:Ubiquitin-Conjugating Enzymes; D044767:Ubiquitin-Protein Ligases; D015003:Yeasts / Q000235:genetics / Q000378:metabolism
C090575:ADA2 protein, S cerevisiae; C066955:ARG80 protein, S cerevisiae; C067875:ARG81 protein, S cerevisiae; D003470:Culture Media; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D006657:Histones; D026341:Minichromosome Maintenance 1 Protein; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D001120:Arginine; C471606:RAD6 protein, S cerevisiae; D044763:Ubiquitin-Conjugating Enzymes; C066066:UBR1 protein, S cerevisiae; D044767:Ubiquitin-Protein Ligases; C425775:ARG82 protein, S cerevisiae; D017853:Phosphotransferases (Alcohol Group Acceptor); D008025:Ligases; D001124:Argininosuccinate Synthase