Functions Of Protein Kinases RCK2 And HOG1 In High Osmolar Stress, Oxidative Stresses And Cell Wall Integrity In Saccharomycese Cerevisiae And Candida Albicans

Rck2p is a Hog1p-MAP kinase activated protein kinase and regulates osmotic and oxidative stresses in budding yeast. In this study, we have demonstrated that in both Saccharomycese cerevisiae and, the most medically important human fungal pathogen, Candida albicans deletion of RCK2 causes cells sensitive to rapamycin, the inhibitor of TOR (target of rapamycin) protein kinase controlling cell growth. In addition, the kinase activity of Rck2p seems to be not required for this rapamycin sensitive function in both eukaryotic microorganisms. We also have found that CaRCK2 and its kinase activity are required for cell growth in C. albicans. Furthermore, we have found that Candida cells deleted for CaRCK2 display an increased sensitivity to high osmotic stress, oxidative stress and agents disrupting cell wall integrity, whereas yeast cells deleted for ScRCK2 only show an increased sensitivity to oxidative stress. Our results indicate that RCK2 plays divergent roles in C. albicans and budding yeast cells.We also found that deletion of HOG1 and PBS2 as well as genes encoding HOG1-regulated transcription factors does not affect the rapamycin sensitivity in S. cerevisiae, whereas disruption of CaHOG1 causes cells sensitive to rapamycin in C. albicans. These results suggest that the HOG pathway also plays divergent roles in C. albicans and budding yeast cells.