Mapping of yeast Rpn4p transactivation domains.

The 26S proteasome is a multi-subunit protease complex and plays an essential role in many basic cellular processes. The abundance of the 26S proteasome is controlled by a negative feedback circuit that involves the Rpn4p transcriptional activator. To date, the functional regions of Rpn4p are largely unknown. We mapped the Rpn4p transactivation domains by deletion analysis. The distal acidic domain has stronger transactivation potential than that of the proximal acidic domain. However, the N-terminal region, and not the acidic domains of Rpn4p, is crucial for Rpn4p function. Within the N-terminus, we mapped a novel transactivation domain, which may be regulated by some modification of lysines in a proteolysis-independent manner.