Ash1p is a site-specific DNA-binding protein that actively represses transcription.
ASH1 encodes a protein that is localized specifically to the daughter cell nucleus, where it has been proposed to repress transcription of the HO gene. Using Ash1p purified from baculovirus-infected insect cells, we have shown that Ash1p binds specific DNA sequences in the HO promoter. DNase I protection analyses showed that Ash1p recognizes a consensus sequence, YTGAT. Mutation of this consensus abolishes Ash1p DNA binding in vitro. We have shown that Ash1p requires an intact zinc-binding domain in its C terminus for repression of HO in vivo and that this domain may be involved in DNA binding. A heterologous DNA-binding domain fused to an N-terminal segment of Ash1p functions as an active repressor of transcription. Our studies indicate that Ash1p is a DNA-binding protein of the GATA family with a separable transcriptional repression domain.
Maxon
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ME
Department of Biochemistry and Biophysics, University of California, 513 Parnassus Avenue, San Francisco, CA 94143-0448, USA.
Herskowitz
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I
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D011817:Rabbits; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D018411:Spodoptera / Q000166:cytology; D013329:Structure-Activity Relationship; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D016335:Zinc Fingers
C098733:ASH1 protein, S cerevisiae; D004268:DNA-Binding Proteins; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors