A central role for SWI6 in modulating cell cycle Start-specific transcription in yeast
Abstract
MOST genes involved in DNA replication in the yeast Saccharomyces cerevisiaeare transcribed transiently during late Gl as cells become committed to a new cell cycle at Start1. Their promoters all contain one or more versions of an 8-base-pair motif (ACGCGTNA) containing an Mlu I restriction enzyme site and called the Mlu I cell-cycle box (MCB)2. MCBs are both necessary and sufficient for the late Gl-specific transcription of theTMP1 thymidylate synthase andPOL1 DNA polymerase genes3,4. A different late Gl-specific 8-base-pair transcription element called the SCB (CACGAAAA; ref. S) is bound by a factor containing the Swi4 and Swi6 proteins6,7. We describe here the formation in vitro of complexes on TMP1 MCBs that contain the Swi6 protein and, we suggest, a protein of relative molecular mass 120,000 (p!20) that is distinct from Swi4. Transcription due to SCBs and MCBs occurs in the absence of Swi6 but it is no longer correctly regulated in the cell cycle. We suggest that Swi6 is an essential regulatory subunit of two different Start-dependent transcription factors. One factor (SBF) contains Swi4 and binds to SCBs, whereas the other (MBF) contains the protein p120 and binds MCBs.
- Publication:
-
Nature
- Pub Date:
- June 1992
- DOI:
- 10.1038/357508a0
- Bibcode:
- 1992Natur.357..508D