Beyond the Identification of Transcribed Sequences:
Functional, Evolutionary and Expression Analysis
12th International Workshop
October 25-28, 2002
Washington, DC

List of Abstracts * Speakers * Organizers * Authors * Original Announcement

Complex Transcriptional Circuitry at the G1/S transition in Saccharomyces cerevisiae

Christine E. Horak, Nicholas M. Luscombe, Jiang Qian, Stacy Piccirrillo, Mark Gerstein and Michael Snyder
Department of Molecular, Cellular and Developmental Biology and Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8103
Telephone: 203 432 6139
Fax: 203 432 3597

In the yeast Saccharomyces cerevisiae, SBF (Swi4-Swi6 cell cycle box binding factor) and MBF (MluI binding factor) are the major transcription factors regulating the START of the cell cycle, a time just before DNA replication, bud growth initiation and spindle pole body duplication. These two factors bind to the promoters of 235 genes, but bind less than a quarter of the promoters upstream of genes with peak transcript levels at the G1 phase of the cell cycle (Iyer et al. 2001). Several functional categories, which are known to be crucial for G1/S events, such as spindle pole body duplication/migration and DNA synthesis are underrepresented in the list of SBF and MBF gene targets. SBF binds the promoters of several other transcription factors including HCM1, PLM2, POG1, TOS4, TOS8, TYE7, YAP5, YHP1 and YOX1. Here, we demonstrate that these factors are targets of SBF using an independent assay. To further elucidate the transcriptional circuitry that regulates the G1 to S phase progression, these factors were epitope-tagged and their binding targets were identified by chIp-chip analysis. These factors bind the promoters of genes with roles in G1/S events including DNA replication, bud growth, spindle pole complex formation, as well as the general activities of mitochondrial function, transcription and protein synthesis. While functional overlap exists between these factors and MBF and SBF, each of these factors has distinct functional roles. Most of these factors bind the promoters of other transcription factors known to be cell cycle regulated or known to be important for cell cycle progression and differentiation processes indicating that a complex network of transcription factors coordinates the diverse activities that initiate a new cell cycle.

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