title: Interaction of the yeast Swi4 and Swi6 cell cycle regulatory proteins in vitro.
abstract: In budding yeast, two transcription factors, Swi4 and Swi6, control the expression of important cell cycle regulatory proteins (the G1 cyclins, Cln1 and Cln2, and the cyclin-like Hcs26) as well as the HO gene, whose product initiates mating-type switching. Both Swi4 and Swi6 are components of a protein complex that forms at a repeated sequence element, SCB (SWI4, -6-dependent cell cycle box), found in the upstream regulatory sequences of target genes. We show, by using proteins synthesized in vitro, a direct association between Swi4 and Swi6. The cdc10-Swi6 or ankyrin motifs present in both Swi4 and Swi6 are dispensable for their association, which is mediated instead by a region near the C terminus of each protein. Furthermore, we show that interaction with Swi6 is not necessary for specific recognition of the SCB sequence by the Swi4 protein; we propose that Swi4 is responsible for binding to the SCB sequence while Swi6, through its association with Swi4, regulates activity of the complex.
authors: Department of Molecular and Medical Genetics, University of Toronto, ON, Canada.
authors: B J
authors: BJ
authors: Andrews
authors: L A
authors: LA
authors: Moore
mesh_terms: D002453:Cell Cycle; D004268:DNA-Binding Proteins / Q000502:physiology*; D005656:Fungal Proteins / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D066298:In Vitro Techniques; D046911:Macromolecular Substances; D011994:Recombinant Proteins; D012441:Saccharomyces cerevisiae / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins; D017384:Sequence Deletion; D013329:Structure-Activity Relationship; D014157:Transcription Factors / Q000378:metabolism* / Q000502:physiology*
chemical_list: D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D046911:Macromolecular Substances; D011994:Recombinant Proteins; C062214:SWI4 protein, S cerevisiae; C075111:SWI6 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors