Steven J. Triezenberg Research Interests continued
These two subdomains seem to function by distinct mechanisms, including preferences for different kinds of core gene promoters. Although VP16 and other activators are rich in acidic amino acids, the most important residues are hydrophobic or aromatic amino acids. The structure of this domain is quite flexible until it interacts with its target proteins as part of the mechanism of activation. A surprising number of such target proteins have been identified, including basal transcription factors and co-activator or adaptor proteins. These discoveries have significant implications for models of transcriptional regulation in general and for the potential of VP16 as a target for antiviral therapy.
In collaboration with MSU colleague Mike Thomashow, we have begun to explore one mechanism of transcriptional activation in plants. The expression of certain genes is induced when plants encounter cold temperatures, as one aspect of the protective mechanism termed cold acclimation. When a transcription factor involved in this genetic switch was introduced into yeast cells, its activity depended on a complex of proteins termed transcriptional adaptors (initially identified in yeast experiments performed with VP16!). One function of this adaptor complex is to acetylate histones and thereby to relieve the repression of transcription caused by packaging DNA into chromatin. We have now isolated genes encoding several transcriptional adaptor proteins from the model plant organism Arabidopsis, and are launching molecular genetic and biochemical studies of the role of histone acetylation by these proteins during plant gene expression.
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