Activation Domain Shielding

Synonyms

Shielding of activation domain

Definition

In budding yeast, several GAL genes including GAL1, GAL10, and GAL7 are activated by Gal4p, which is a transcriptional activator for the GAL regulon. Expression of the GAL genes allows the cell to utilize the sugar galactose as a carbon source. In the absence of galactose, Gal4p is bound to DNA but is inactive because its activation domain (AD) is masked by Gal80p (Fig. 1a) (Wong and Struhl 2011). Once galactose is added to the media, the signal transduction protein Gal3p binds the sugar along with ATP to allow activation of Gal4p. Specifically, the galactose- and ATP-bound form of Gal3p can form a stable complex with Gal80p, thereby titrating out the inhibitory effect of Gal80p on Gal4p (Lavy et al. 2012). It is not known whether Gal80p is released from the transcription complex upon activation or instead remains in complex with Gal3p, possibly in a different position or orientation. Regardless, upon binding of Gal3p and Gal80p, the...