Enhancement of menadione stress tolerance in yeast by accumulation of hypotaurine and taurine: co-expression of cDNA clones, from Cyprinus carpio, for cysteine dioxygenase and cysteine sulfinate decarboxylase in Saccharomyces cerevisiae.

Taurine is known to function as a protectant against various stresses in animal cells. In order to utilize taurine as a compatible solute for stress tolerance of yeast, isolation of cDNA clones for genes encoding enzymes involved in biosynthesis of taurine was attempted. Two types of cDNA clones corresponding to genes encoding cysteine dioxygenase (CDO1 and CDO2) and a cDNA clone for cysteine sulfinate decarboxylase (CSD) were isolated from Cyprinus carpio.

Two low-temperature-inducible Chlorella genes for delta12 and omega-3 fatty acid desaturase (FAD): isolation of delta12 and omega-3 fad cDNA clones, expression of delta12 fad in Saccharomyces cerevisiae, and expression of omega-3 fad in Nicotiana tabacum.

In an attempt to clarify the involvement of fatty acid desaturases (FADs) in the freezing tolerance of Chlorella vulgaris IAM C-27, developed by hardening, we have isolated cDNA clones for two types of FADs from the Chlorella strain, based on the sequence information of genes for delta12 and omega-3 FADs, respectively desaturating oleic acid (18:1) to linoleic acid (18:2) and linoleic acid (18:2) to linolenic acid (18:3). The deduced amino acid sequence of the first clone, designated CvFad2, showed about 66% similarity to the microsomal delta12 FADs from several higher plants and this gene had delta12 FAD activity when expressed in Saccharomyces cerevisiae. The predicted protein encoded by a second gene, designated CvFad3, showed about 60% similarity to the microsomal and plastidial omega-3 FADs from several higher plants.