The yeast protein complex containing cdc68 and pob3 mediates core-promoter repression through the cdc68 N-terminal domain.
Transcription of nuclear genes usually involves trans-activators, whereas repression is exerted by chromatin. For several genes the transcription mediated by trans-activators and the repression mediated by chromatin depend on the CP complex, a recently described abundant yeast nuclear complex of the Pob3 and Cdc68/Spt16 proteins. We report that the N-terminal third of the Saccharomyces cerevisiae Cdc68 protein is dispensable for gene activation but necessary for the maintenance of chromatin repression. The absence of this 300-residue N-terminal domain also decreases the need for the Swi/Snf chromatin-remodeling complex in transcription and confers an Spt- effect characteristic of chromatin alterations. The repression domain, and indeed the entire Cdc68 protein, is highly conserved, as shown by the sequence of the Cdc68 functional homolog from the yeast Kluyveromyces lactis and by database searches. The repression-defective (truncated) form of Cdc68 is stable but less active at high temperatures, whereas the known point-mutant form of Cdc68, encoded by three independent mutant alleles, alters the N-terminal repression domain and destabilizes the mutant protein.
Evans
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DR
Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia B3H 4H7, Canada.
Brewster
N K
NK
Xu
Q
Q
Rowley
A
A
Altheim
B A
BA
Johnston
G C
GC
Singer
R A
RA
D000251:Adenosine Triphosphatases; D000595:Amino Acid Sequence; D001665:Binding Sites; D002352:Carrier Proteins / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002868:Chromosomal Proteins, Non-Histone; D017124:Conserved Sequence; D004268:DNA-Binding Proteins / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal; D006657:Histones; D007716:Kluyveromyces / Q000235:genetics; D008969:Molecular Sequence Data; D009687:Nuclear Proteins; D010455:Peptides / Q000235:genetics; D017354:Point Mutation; D011401:Promoter Regions, Genetic; D046988:Proteasome Endopeptidase Complex; D012097:Repressor Proteins / Q000235:genetics; D000071796:SMARCB1 Protein; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D013696:Temperature; D014157:Transcription Factors / Q000235:genetics; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D035602:Transcriptional Elongation Factors
D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D006657:Histones; D009687:Nuclear Proteins; C106768:POB3 protein, S cerevisiae; D010455:Peptides; D012097:Repressor Proteins; D000071796:SMARCB1 Protein; C513266:SMARCB1 protein, human; C066190:SNF5 protein, S cerevisiae; C071238:SPT16 protein, S cerevisiae; C489489:SUPT16H protein, human; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D035602:Transcriptional Elongation Factors; D046988:Proteasome Endopeptidase Complex; D000251:Adenosine Triphosphatases; C499333:SNF2 protein, S cerevisiae; C069670:RPT6 protein, S cerevisiae