A Single Amino Acid Change Converts an Inhibitory Transcription Factor into an Activator

This is the authors' abstract. We don't add key points for this paper.

The closely related POU family transcription factors Brn-3a and Brn-3b differ in their functional activity with Brn-3a activating several target promoters, which are repressed by Brn-3b. Brn-3b also prevents promoter activation by Brn-3a. Here we have altered a single isoleucine residue in the POU homeodomain of Brn-3b to the valine residue found at the equivalent position in Brn-3a. This change not only abolishes the ability of Brn-3b to repress basal and Brn-3a-stimulated promoter activity but also converts it to an activator of similar potency to Brn-3a. Hence a single amino acid difference determines the difference between an activator and a repressor in the Brn-3 family.