Prelich, G. & Winston, F. Mutations that suppress the deletion of an upstream activating sequence in yeast: involvement of a protein kinase and histone H3 in repressing transcription in vivo. Genetics 135, 665-676

Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115.
Genetics (Impact Factor: 5.96). 12/1993; 135(3):665-76.
Source: PubMed


Regulated transcription of most protein-encoding genes in Saccharomyces cerevisiae requires an upstream activating sequence (UAS); in the absence of UAS elements, little or no transcription occurs. In certain mutant strains, however, promoters that have been deleted for their UAS can direct significant levels of transcription, indicating that the remaining promoter elements (the basal promoter) are capable of directing higher levels of transcription, but they are normally represented in wild-type strains. To analyze this repression, we have selected for mutations that cause increased transcription of the SUC2 gene in the absence of its UAS. In addition to some previously studied genes, this selection has identified five genes that we have designated BUR1, BUR2, BUR3, BUR5 and BUR6 (for Bypass UAS Requirement). The bur mutations cause pleiotropic phenotypes, indicating that they affect transcription of many genes. Furthermore, some bur mutations suppress the requirement for the SNF5 trans-activator at both SUC2 and Ty. Additional analysis has demonstrated that BUR1 is identical to SGV1, which encodes a CDC28-related protein kinase. This result indicates that protein phosphorylation is important for repression of the SUC2 basal promoter as well as other aspects of transcription in vivo. Finally, BUR5 is identical to HHT1, encoding histone H3, further implicating chromatin structure as important for expression of SUC2.

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    • "Our lab has been using a genetic approach to identify transcriptional regulators in Saccharomyces cerevisiae, screening for mutations that increase transcription from the UAS-less suc2Δuas(−1900/−390) reporter [30], [31]. This Bur- (Bypass UAS Requirement) selection has been very successful, revealing mutations in genes that regulate TATA-Binding Protein, RNA polymerase II, and histones [30], [32], [33]. A yeast strain containing the suc2Δuas(−1900/−390) reporter was subsequently screened for genes whose overexpression causes in the Bur- phenotype, resulting in the isolation of a single gene, IRC20 [34]. "
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    ABSTRACT: A considerable percentage of the genome is dedicated to the ubiquitin-proteasome system, with the yeast genome predicted to encode approximately 100 ubiquitin ligases (or E3s), and the human genome predicted to encode more than 600 E3s. The most abundant class of E3s consists of RING finger-containing proteins. Although many insights have been obtained regarding the structure and catalytic mechanism of the E3s, much remains to be learned about the function of the individual E3s. Here we characterize IRC20, which encodes a dual RING- and Snf/Swi family ATPase domain-containing protein in yeast that has been implicated in DNA repair. We found that overexpression of IRC20 causes two transcription-associated phenotypes and demonstrate that the Irc20 RING domain possesses ubiquitin E3 activity in vitro. Two mass spectrometry approaches were undertaken to identify Irc20-associated proteins. Wild-type Irc20 associated with Cdc48, a AAA-ATPase that serves as an intermediary in the ubiquitin-proteasome system. A second approach using a RING mutant derivative of Irc20 detected increased association of the Irc20 mutant with SUMO. These findings provide a foundation for understanding the roles of Irc20 in transcription and DNA repair.
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    • "The SPT genes encode many proteins important in transcription, including subunits of the SAGA histone-modifying complex (Grant et al. 1998), TBP itself, and histones (Clark-Adams et al. 1988; Winston and Sudarsanam 1998; Yamaguchi et al. 2001). SPT10 is not an essential gene, but the null allele is associated with very slow growth and defects in gene regulation (Denis and Malvar 1990; Natsoulis et al. 1991; Prelich and Winston 1993; Yamashita 1993; Dollard et al. 1994; Natsoulis et al. 1994). Spt10 contains a histone acetyltransferase (HAT) domain similar to that of Gcn5 (Neuwald and Landsman 1997), but it has not been possible to demonstrate HAT activity, despite many attempts by our laboratory and others. "
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    ABSTRACT: We discuss the regulation of the histone genes of the budding yeast Saccharomyces cerevisiae. These include genes encoding the major core histones (H3, H4, H2A, and H2B), histone H1 (HHO1), H2AZ (HTZ1), and centromeric H3 (CSE4). Histone production is regulated during the cell cycle because the cell must replicate both its DNA during S phase and its chromatin. Consequently, the histone genes are activated in late G1 to provide sufficient core histones to assemble the replicated genome into chromatin. The major core histone genes are subject to both positive and negative regulation. The primary control system is positive, mediated by the histone gene-specific transcription activator, Spt10, through the histone upstream activating sequences (UAS) elements, with help from the major G1/S-phase activators, SBF (Swi4 cell cycle box binding factor) and perhaps MBF (MluI cell cycle box binding factor). Spt10 binds specifically to the histone UAS elements and contains a putative histone acetyltransferase domain. The negative system involves negative regulatory elements in the histone promoters, the RSC chromatin-remodeling complex, various histone chaperones [the histone regulatory (HIR) complex, Asf1, and Rtt106], and putative sequence-specific factors. The SWI/SNF chromatin-remodeling complex links the positive and negative systems. We propose that the negative system is a damping system that modulates the amount of transcription activated by Spt10 and SBF. We hypothesize that the negative system mediates negative feedback on the histone genes by histone proteins through the level of saturation of histone chaperones with histone. Thus, the negative system could communicate the degree of nucleosome assembly during DNA replication and the need to shut down the activating system under replication-stress conditions. We also discuss post-transcriptional regulation and dosage compensation of the histone genes.
    Full-text · Article · May 2012 · Genetics
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    • "First, it was shown that suppressors of snf2/swi2 mutations included mutations in HTA1-HTB1, encoding histones H2A-H2B, and in SPT6, encoding a histone chaperone (Neigeborn et al. 1986, 1987; Clark-Adams and Winston 1987; Hirschhorn et al. 1992). This genetic relationship between Swi/Snf and chromatin was fortified by other results that showed that suppressors of swi1, swi2, and swi3 mutations were in histone H3-and H4-encoding genes (Prelich and Winston 1993; Kruger et al. 1995). Thus, genetics suggested that the transcriptional activation defects caused by loss of Swi/Snf could be bypassed by reducing or altering nucleosome function. "
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    ABSTRACT: Understanding the mechanisms by which chromatin structure controls eukaryotic transcription has been an intense area of investigation for the past 25 years. Many of the key discoveries that created the foundation for this field came from studies of Saccharomyces cerevisiae, including the discovery of the role of chromatin in transcriptional silencing, as well as the discovery of chromatin-remodeling factors and histone modification activities. Since that time, studies in yeast have continued to contribute in leading ways. This review article summarizes the large body of yeast studies in this field.
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