HPR1 encodes a global positive regulator of transcription in Saccharomyces cerevisiae.
The Hpr1 protein has an unknown function, although it contains a region of homology to DNA topoisomerase I. We have found that hpr1 null mutants are defective in the transcription of many physiologically unrelated genes, including GAL1, HO, ADH1, and SUC2, by using a combination of Northern (RNA) blot analysis, primer extension, and upstream activation sequence-lacZ fusions. Many of the genes positively regulated by HPR1 also require SWI1, SWI2-SNF2, SWI3, SNF5, and SNF6. The transcriptional defect at HO and the CCB::lacZ upstream activation sequence in hpr1 mutants is partially suppressed by a deletion of SIN1, which encodes an HMG1p-like protein. Elevated gene dosage of either histones H3 and H4 or H2A and H2B results in a severe growth defect in combination with an hpr1 null mutation. However, increased gene dosage of all four histones simultaneously restores near-normal growth in hpr1 mutants. Altered in vivo Dam methylase sensitivity is observed at two HPR1-dependent promoters (GAL1 and SUC2). Most of the Hpr1 protein present in the cell is in a large complex (10(6) Da) that is distinct from the SWI-SNF protein complex. We propose that HPR1 affects transcription and recombination by altering chromatin structure.
Zhu
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Y
Department of Radiation Oncology, University of California, San Francisco 94143.
Peterson
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CL
Christman
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MF
D001483:Base Sequence; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D017931:DNA Primers; D005656:Fungal Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D005838:Genotype; D008780:Methyltransferases / Q000378:metabolism; D008969:Molecular Sequence Data; D009687:Nuclear Proteins; D010957:Plasmids; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D017384:Sequence Deletion; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific); D013489:Suppression, Genetic; D014157:Transcription Factors / Q000096:biosynthesis*; D014158:Transcription, Genetic
D017931:DNA Primers; D005656:Fungal Proteins; C063494:HPR1 protein, S cerevisiae; D009687:Nuclear Proteins; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D008780:Methyltransferases; C058693:Dam methyltransferase; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific)