Functional characterization of human and fungal MAP kinases in Saccharomyces cerevisiae

A functional comparison of three human SAPKs with fungal Hog1p was undertaken, using Saccharomyces cerevisiae as a heterologous expression system. We characterized the role of mammalian MAP kinases in sensitivity to both osmotic and oxidative stress of a S. cerevisiae hog1 mutant. Western blot analyses indicated that S. cerevisiae can only phosphorylate mammalian MAP kinases in response to osmotic stress but not to oxidative stress, while morphogenetic defects characteristic of hog1 mutants under hyperosmotic stress are only suppressed by fungal and not mammalian Hog1p. Our data demonstrate the functional conservation of MAPKs although they also evidence differential aspects among the three human SAPKs and the fungal MAPKs. Copyright (c) 2007 John Wiley & Sons, Ltd.