The Zygosaccharomyces rouxii strain CBS732 contains only one copy of the HOG1 and the SOD2 genes

The osmotolerant yeast Zygosaccharomyces rouxii CBS732 contains only one co py of the ZrHOG1 and ZrSOD2-22 genes. Both genes were cloned and sequenced (Acc. Nos. AJ132606 and AJ252273, respectively) and their sequences were co mpared to homologous pairs of genes from Z. rouxii ATCC42981 (genes Z-HOG1, Z-HOG2, 2-SOD2, Z-SOD22). The CBS732 ZrHog1p is shorter than its ATCC42981 counterparts (380 aa residues vs. 407 and 420 aa, respectively) and is mor e similar to ATCC42981 Z-Hog2p than to Z-Hog1p. Also its promoter region co rresponds to that one of Z-NOG2. The CBS732 ZrHOG1 promoter region is recog nised by Saccharomyces cerevisiae, and the gene product (MAP kinase ZrHog1p ) presence fully complements the osmosensitivity of a S. cerevisiae hog1 mu tant strain. The CBS ZrSOD2-22 gene is highly similar to ATCC42981 Z-SOD2 b ut it contains also a segment of 15 aa residues specific for 2-SOD22. Z. ro uxii ZrSod2-22 Na+/H+ antiporter expressed in S. cerevisiae shows better ac tivity toward toxic Na+ and Li+ cations than does S. cerevisiae's own Nha1 antiporter, and is efficient in improving the halotolerance of some S. cere visiae wild types. (C) 2001 Elsevier Science B.V. All rights reserved.