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

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 Komagataella pfaffii ( Pichia pastoris ), 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.