Complementary function of mitogen-activated protein kinase Hog1 from Trichosporonoides megachiliensis in Saccharomyces cerevisiae under hyper-osmotic stress.

A (TmHog1) gene encoding a mitogen-activated protein kinase (MAPK) homologous to Saccharomyces cerevisiae Hog1 (ScHog1) involved in hyper-osmotic stress signaling was isolated from Trichosporonoides megachiliensis SN-124A, an erythritol-producing yeast. Although TmHog1, like other Hog1 homologs, encoded a kinase catalytic domain containing TGY motif, it was 50-60 amino acid residues shorter than the ScHog1. A TmHog1 transgene rescued the osmotic sensitivity and glycerol production defect of S. cerevisiae hog1Δ, a highly osmo-sensitive strain that does not produce glycerol, a compatible solute, during osmotic stress. Functional analyses of chimeric Hog1 proteins constructed from ScHog1 and TmHog1 sequences indicated that the C-terminal region of TmHog1 is more effective for glycerol biosynthesis than ScHog1 under osmotic stress.