SWI5 instability may be necessary but is not sufficient for asymmetric HO expression in yeast.
Open Access
- 1 March 1993
- journal article
- research article
- Published by Cold Spring Harbor Laboratory in Genes & Development
- Vol. 7 (3), 517-528
- https://doi.org/10.1101/gad.7.3.517
Abstract
Homothallic haploid yeast cells divide to produce a mother cell that switches mating type and a daughter cell that does not. This pattern is the result of HO endonuclease transcription exclusively in mother cells, and there only transiently in late G1 as cells undergo Start. SWI5 encodes an HO transcription factor that is expressed during the S, G2, and M phases of the cell cycle. The lack of synthesis of SWI5 during G1 is essential to prevent HO transcription in daughter cells. Thus, HO must be activated by SWI5 protein synthesized in the previous cell cycle if it is to be properly regulated. SWI5 is inherited by both mother and daughter cells, and we show here that most of it is rapidly degraded during early G1. More stable mutant SWI5 proteins cause daughter cells to switch mating type, suggesting that SWI5 destruction is necessary to prevent HO expression in daughters. We show further that mother cells can still express HO when stimulated to undergo Start after arrest in early G1 for several hours. We propose that a small fraction of the SWI5 protein inherited by mother cells is extremely stable and that the crucial difference between mothers and daughters with regard to HO transcription is their differential ability to sequester SWI5 in a stable form, possibly as a component of transcription complexes on the HO promoter.Keywords
This publication has 37 references indexed in Scilit:
- Adjacent zinc-finger motifs in multiple zinc-finger peptides from SWI5 form structurally independent, flexibly linked domainsJournal of Molecular Biology, 1992
- Characterization of the yeast SWI1, SWI2, and SWI3 genes, which encode a global activator of transcriptionCell, 1992
- Changes in a SWI4,6-DNA-binding complex occur at the time of HO gene activation in yeast.Genes & Development, 1991
- Zinc-finger motifs expressed in E. coli and folded in vitro direct specific binding to DNANature, 1988
- Both positive and negative regulators of HO transcription are required for mother-cell-specific mating-type switching in yeastCell, 1987
- Five SWI genes are required for expression of the HO gene in yeastJournal of Molecular Biology, 1984
- Structural rearrangements of tubulin and actin during the cell cycle of the yeast Saccharomyces.The Journal of cell biology, 1984
- Molecular analysis of a cell lineageNature, 1983
- Directionality of yeast mating-type interconversionCell, 1982
- Binding of a simian virus 40 T antigen-related protein to DNAJournal of Molecular Biology, 1981