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Query: UNIPROT:P06126 (CD1a)
 2,221 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Changes in histone gene dosage as well as mutations within some histone genes suppress delta insertion mutations in the HIS4 and LYS2 loci of Saccharomyces cerevisiae by altering the site of transcription initiation. We have found that three histone regulatory (hir) mutations, identified by their effects on the regulation of histone gene expression, suppress the same insertion mutations. In addition, we have examined whether any previously identified spt (suppressor of Ty) mutations might suppress the delta insertion alleles because of effects on histone gene regulation. Our results demonstrate that mutations in the histone genes SPT11/HTA1 and SPT12/HTB1 and in three other SPT genes, SPT1, SPT10 and SPT21, confer Hir- phenotypes. The spt1 mutation was found to be an allele of HIR2 while the spt10 and spt21 mutations are not in any of the known HIR genes.
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PMID:Histone regulatory (hir) mutations suppress delta insertion alleles in Saccharomyces cerevisiae. 165 65

Both activation and repression have been implicated in the cell cycle-regulated transcription of the histone HTA1-HTB1 locus in Saccharomyces cerevisiae. Transcriptional repressors have been identified through the isolation of recessive mutations in the HIR1, HIR2 and HIR3 genes. These three regulatory genes encode proteins that act at a negative site in the HTA1-HTB1 promoter, and their inactivation results in cell cycle-independent transcription. We report here on the characterization of a fourth HIR mutant. The HIR4-1 mutation is dominant, and the phenotypes that it confers suggest that the mutant gene encodes an altered transcriptional activator. The function of this activator is very specific: it uniquely regulates transcription of the HTA1-HTB1 locus, and it may antagonize repressors that act through the HTA1-HTB1 negative site.
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PMID:The HIR4-1 mutation defines a new class of histone regulatory genes in Saccharomyces cerevisiae. 822 24

The products of the HIR1 and HIR2 genes have been defined genetically as repressors of histone gene transcription in S. cerevisiae. A mutation in either gene affects cell cycle regulation of three of the four histone gene loci; transcription of these loci occurs throughout the cell cycle and is no longer repressed in response to the inhibition of DNA replication. The same mutations also eliminate autogenous regulation of the HTA1-HTB1 locus by histones H2A and H2B. The HIR1 and HIR2 genes have been isolated, and their roles in the transcriptional regulation of the HTA1-HTB1 locus have been characterized. Neither gene encodes an essential protein, and null alleles derepress HTA1-HTB1 transcription. Both HIR genes are expressed constitutively under conditions that lead to repression or derepression of the HTA1 gene, and neither gene regulates the expression of the other. The sequence of the HIR1 gene predicts an 88-kDa protein with three repeats of a motif found in the G beta subunit of retinal transducin and in a yeast transcriptional repressor, Tup1. The sequence of the HIR2 gene predicts a protein of 98 kDa. Both gene products contain nuclear targeting signals, and the Hir2 protein is localized in the nucleus.
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PMID:Characterization of HIR1 and HIR2, two genes required for regulation of histone gene transcription in Saccharomyces cerevisiae. 841 31

The SPT4, SPT5, and SPT6 gene products define a class of transcriptional repressors in Saccharomyces cerevisiae that are thought to function through their effects on chromatin assembly or stability. Mutations in these genes confer a similar range of phenotypes to mutations in HIR genes, which encode transcriptional repressors that regulate expression of many of the core histone genes. Here we show that mutations in the three SPT genes also affect transcription of the histone genes that reside at the HTA1-HTB1 locus. HTA1-lacZ transcription was reduced in each spt mutant background, an effect that required a negative site in the HTA1 promoter. The transcriptional effect could be reversed by the overproduction of histones H2A and H2B in an spt4 mutant and histones H3 and H4 in all three spt mutants. Suppression of the spt4 transcriptional defect was dependent on the overproduction of both histones H2A and H2B, and required the presence of N-terminal amino acids in both histones. The results are consistent with the idea that the effects of the spt mutations on nucleosome assembly and/or stability activate repressors of HTA1 transcription.
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PMID:Mutations in the SPT4, SPT5, and SPT6 genes alter transcription of a subset of histone genes in Saccharomyces cerevisiae. 884 44

The HIR/HPC (histone regulation/histone periodic control) negative regulators play important roles in the transcription of six of the eight core histone genes during the Saccharomyces cerevisiae cell cycle. The phenotypes of hir1 and hir2 mutants suggested that the wild-type HIR1 and HIR2 genes encode transcriptional repressors that function in the absence of direct DNA binding. When Hir1p and Hir2p were artificially tethered to yeast promoters, each protein repressed transcription, suggesting that they represent a new class of transcriptional corepressors. The two proteins might function as a complex in vivo: Hir2p required both Hir1p and another Hir protein, Hir3p, to repress transcription when it was tethered to an HTA1-lacZ reporter gene, and Hir1p and Hir2p could be coimmunoprecipitated from yeast cell extracts. Tethered Hir1p also directed the periodic transcription of the HTA1 gene and repressed HTA1 transcription in response to two cell cycle regulatory signals. Thus, it represents the first example of a transcriptional corepressor with a direct role in cell cycle-regulated transcription.
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PMID:Hir1p and Hir2p function as transcriptional corepressors to regulate histone gene transcription in the Saccharomyces cerevisiae cell cycle. 900 Dec 7

Transcription of the four yeast histone gene pairs (HTA1-HTB1, HTA2-HTB2, HHT1-HHF1, and HHT2-HHF2) is repressed during G1, G2, and M. For all except HTA2-HTB2, this repression requires several trans-acting factors, including the products of the HIR genes, HIR1, HIR2, and HIR3. ASF1 is a highly conserved protein that has been implicated in transcriptional silencing and chromatin assembly. In this analysis, we show that HIR1 interacts with ASF1 in a two-hybrid analysis. Further, asf1 mutants, like hir mutants, are defective in repression of histone gene transcription during the cell cycle and in cells arrested in early S phase in response to hydroxyurea. asf1 and hir1 mutations also show very similar synergistic interactions with mutations in cac2, a subunit of the yeast chromatin assembly factor CAF-I. The results suggest that ASF1 and HIR1 function in the same pathway to create a repressive chromatin structure in the histone genes during the cell cycle.
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PMID:Yeast ASF1 protein is required for cell cycle regulation of histone gene transcription. 1140 24

We describe a fluorescent reporter system that exploits the functional genomic tools available in budding yeast to systematically assess consequences of genetic perturbations on gene expression. We used our Reporter-Synthetic Genetic Array (R-SGA) method to screen for regulators of core histone gene expression. We discovered that the histone chaperone Rtt106 functions in a pathway with two other chaperones, Asf1 and the HIR complex, to create a repressive chromatin structure at core histone promoters. We found that activation of histone (HTA1) gene expression involves both relief of Rtt106-mediated repression by the activity of the histone acetyltransferase Rtt109 and restriction of Rtt106 to the promoter region by the bromodomain-containing protein Yta7. We propose that the maintenance of Asf1/HIR/Rtt106-mediated repressive chromatin domains is the primary mechanism of cell-cycle regulation of histone promoters. Our data suggest that this pathway may represent a chromatin regulatory mechanism that is broadly used across the genome.
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PMID:Two-color cell array screen reveals interdependent roles for histone chaperones and a chromatin boundary regulator in histone gene repression. 1968 97

In Saccharomyces cerevisiae, the histone chaperone Rtt106 binds newly synthesized histone proteins and mediates their delivery into chromatin during transcription, replication, and silencing. Rtt106 is also recruited to histone gene regulatory regions by the HIR histone chaperone complex to ensure S-phase-specific expression. Here we showed that this Rtt106:HIR complex included Asf1 and histone proteins. Mutations in Rtt106 that reduced histone binding reduced Rtt106 enrichment at histone genes, leading to their increased transcription. Deletion of the chromatin boundary element Yta7 led to increased Rtt106:H3 binding, increased Rtt106 enrichment at histone gene regulatory regions, and decreased histone gene transcription at the HTA1-HTB1 locus. These results suggested a unique regulatory mechanism in which Rtt106 sensed the level of histone proteins to maintain the proper level of histone gene transcription. The role of these histone chaperones and Yta7 differed markedly among the histone gene loci, including the two H3-H4 histone gene pairs. Defects in silencing in rtt106 mutants could be partially accounted for by Rtt106-mediated changes in histone gene repression. These studies suggested that feedback mediated by histone chaperone complexes plays a pivotal role in regulating histone gene transcription.
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PMID:Direct interplay among histones, histone chaperones, and a chromatin boundary protein in the control of histone gene expression. 2290 59