Pathology

E-mail: david.stillman@utah.edu
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Regulation of the Yeast HO gene

The transcriptional regulation of the HO gene is very complex, and has been a prototypic promoter where changes in chromatin structure regulate gene expression. Chromatin Immunoprecipitation experiments show that transcriptional activation of HO involves the sequential binding of various factors, both sequence specific DNA-binding factors and general chromatin factors such as chromatin remodeling factors, histone acetyltransferase complexes, architectural transcription factors, and the Mediator complex. The Swi5 DNA-binding protein is the earliest factor that binds to the HO promoter, and it then recruits other regulatory complexes that remain stably bind long after the unstable Swi5 factor is degraded. Importantly, one can experimentally extend the time between when Swi5 was last bound and when the gene is activated, and the promoter “remembers” the actions of the Swi5 activator. Thus the HO promoter has been described as having a “memory,” and current experiments are defining  this molecularly.

1/2008