Candida glabrata Rpn4-like Protein Complements the RPN4 Deletion in Saccharomyces cerevisiae

Abstract

Expression of Saccharomyces cerevisiae proteasomal genes is regulated in a coordinated manner by a system that includes the ScRpn4 transcription factor and its binding site known as PACE. Earlier we showed that, Rpn4-like proteins from the biotechnologically important yeast species Komagataellapfaffii (Pichiapastoris), Yarrowia lipolytica, and Debaryomyces hansenii are capable of complementing the RPN4 deletion in S. cerevisiae in spite of their low structural similarity to ScRpn4. The opportunistic yeast pathogen Candida glabrata has a gene coding for a Rpn4-like protein, which has not been characterized experimentally yet. The C. glabrata ortholog ScRpn4 was expressed heterologously and found to restore the stress resistance and expression of proteasomal genes in a mutant S. cerevisiae strain with a RPN4 deletion. This complementation required the unique N-terminal region of CgRpn4. The results indicate that CgRpn4 acts as a transcriptional activator of proteasomal genes. The S. cerevisiae model can be used for further structural and functional analyses of CgRpn4.