Rpn4p acts as a transcription factor by binding to PACE, a nonamer box found upstream of 26S proteasomal and other genes in yeast

Abstract

We identified a new, unique upstream activating sequence (5′‐GGTGGCAAA‐3′) in the promoters of 26 out of the 32 proteasomal yeast genes characterized to date, which we propose to call proteasome‐associated control element. By using the one‐hybrid method, we show that the factor binding to the proteasome‐associated control element is Rpn4p, a protein containing a C2H2‐type finger motif and two acidic domains. Electrophoretic mobility shift assays using proteasome‐associated control element sequences from two regulatory proteasomal genes confirmed specific binding of purified Rpn4p to these sequences. The role of Rpn4p to function as a transregulator in yeast is corroborated by its ability of stimulating proteasome‐associated control element‐driven lacZ expression and by experiments using the RPT4 and RPT6 gene promoters coupled to the bacterial cat gene as a reporter. Additionally, we found the proteasome‐associated control element to occur in a number of promoters to genes which are related to the ubiquitin‐proteasome pathway in yeast.