The yeast ubiquitin-like and ubiquitin-associated protein Dsk2 is one of the ubiquitin receptors that function in the ubiquitin-proteasome pathway. We screened the Dsk2-interacting proteins in Saccharomyces cerevisiae
by a two-hybrid assay and identified a novel Dsk2-interacting protein, Irc22, the gene locus of which has previously been described as YEL001C
, but the function of which is unknown. IRC22
encodes 225 amino acid residues with a calculated molecular weight of 25 kDa. The Irc22 protein was detected in yeast cells. IRC22
was a nonessential gene for yeast growth, and its homologs were found among ascomycetous yeasts. Irc22 interacted with Dsk2 in yeast cells, but not with Rad23 and Ddi1. Ubiquitin-dependent degradation was impaired mildly by over-expression or disruption of IRC22.
Compared with the wild-type strain, dsk2D
exhibited salt sensitivity while irc22D
exhibited salt tolerance at high temperatures. The salt-tolerant phenotype that was observed in irc22D
disappeared in the dsk2Dirc22D
double disruptant, indicating that DSK2
is positively and IRC22
is negatively involved in salt stress tolerance. IRC22
disruption did not affect any responses to DNA damage and oxidative stress when comparing the irc22D
and wild-type strains. Collectively, these results suggest that Dsk2 and Irc22 are involved in salt stress tolerance in yeast.