Interaction of a Swi3 homolog with Sth1 provides evidence for a Swi/Snf-related complex with an essential function in Saccharomyces cerevisiae.
The Saccharomyces cerevisiae Swi/Snf complex has a role in remodeling chromatin structure to facilitate transcriptional activation. The complex has 11 components, including Swi1/Adr6, Swi2/Snf2, Swi3, Snf5, Snf6, Snf11, Swp73/Snf12, and Tfg3. Mammalian homologs of these proteins have been shown to form multiple Swi/Snf-related complexes. Here we characterize an S. cerevisiae Swi3 homolog (Swh3) and present evidence that it associates in a complex with a Snf2 homolog, Sthl. We identified Swh3 as a protein that interacts with the N terminus of Snf2 in the two-hybrid system. Swh3 and Swi3 are functionally distinct, and overexpression of one does not compensate for loss of the other. Swh3 is essential for viability and does not activate transcription of reporters. The Snf2 sequence that interacts with Swh3 was mapped to a region conserved in Sth1. We show that Swh3 and Sth1 fusion proteins interact in the two-hybrid system and coimmunoprecipitate from yeast cell extracts. We also map interactions between Swh3 and Sth1 and examine the role of a leucine zipper motif in self-association of Swh3. These findings, together with previous analysis of Sth1, indicate that Swh3 and Sth1 are associated in a complex that is functionally distinct from the Swi/Snf complex and essential for viability.
Treich
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Department of Genetics and Development and Institute of Cancer Research, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA.
Carlson
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D000251:Adenosine Triphosphatases; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D018797:Cell Cycle Proteins; D017124:Conserved Sequence; D004265:DNA Helicases; D004271:DNA, Fungal / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics; D005800:Genes, Fungal; D017930:Genes, Reporter; D006801:Humans; D016350:Leucine Zippers / Q000235:genetics; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics; D009838:Oligodeoxyribonucleotides / Q000235:genetics; D012318:RNA Polymerase I / Q000235:genetics; D012320:RNA Polymerase III / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000254:growth & development; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D015534:Trans-Activators / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics; D015533:Transcriptional Activation
D018797:Cell Cycle Proteins; D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D009687:Nuclear Proteins; D009838:Oligodeoxyribonucleotides; C084011:SMARCA2 protein, human; C072981:SWI3 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D012318:RNA Polymerase I; D012320:RNA Polymerase III; D000251:Adenosine Triphosphatases; C084108:SMARCA4 protein, human; C499333:SNF2 protein, S cerevisiae; C077392:STH1 protein, S cerevisiae; D004265:DNA Helicases