Functional analysis of Debaryomyces hansenii Rpn4 on a genetic background of Saccharomyces cerevisiae

The transcription factor ScRpn4 coordinates the expression of Saccharomyces cerevisiae proteasomal genes. ScRpn4 orthologs are found in a number of other Saccharomycetes yeasts. Their functions, however, have not yet been characterised experimentally in vivo. We expressed the Debaryomyces hansenii DEHA2D12848 gene encoding an ScRpn4 ortholog (DhRpn4), in an S. cerevisiae strain lacking RPN4 . We showed that DhRpn4 activates transcription of proteasomal genes using ScRpn4 binding site and provides resistance to various stresses. The 43–238 aa segment of DhRpn4 contains an unique portable transactivation domain. Similar to the ScRpn4 N-terminus, this domain lacks a compact structure. Moreover, upon overexpression in D. hansenii , DhRpn4 upregulates protesomal genes. Thus, we show that DhRpn4 is the activator for proteasomal genes.