Differential gene expression and Hog1 interaction with osmoresponsive genes in the extremely halotolerant black yeast <it>Hortaea werneckii</it>

• Main Authors: Plemenitaš Ana, Vaupotič Tomaž
• Format: Article
• Language: English
• Published: BMC 2007-08-01
• Series: BMC Genomics
• Online Access: http://www.biomedcentral.com/1471-2164/8/280

<p>Abstract</p> <p>Background</p> <p>Fluctuations in external salinity force eukaryotic cells to respond by changes in the gene expression of proteins acting in protective biochemical processes, thus counteracting the changing osmotic pressure. The high-osmolarity glycerol (HOG) signaling pathway is essential for the efficient up-regulation of the osmoresponsive genes. In this study, the differential gene expression of the extremely halotolerant black yeast <it>Hortaea werneckii </it>was explored. Furthermore, the interaction of mitogen-activated protein kinase HwHog1 and RNA polymerase II with the chromatin in cells adapted to an extremely hypersaline environment was analyzed.</p> <p>Results</p> <p>A cDNA subtraction library was constructed for <it>H. werneckii</it>, adapted to moderate salinity or an extremely hypersaline environment of 4.5 M NaCl. An uncommon osmoresponsive set of 95 differentially expressed genes was identified. The majority of these had not previously been connected with the adaptation of salt-sensitive <it>S. cerevisiae </it>to hypersaline conditions. The transcriptional response in hypersaline-adapted and hypersaline-stressed cells showed that only a subset of the identified genes responded to acute salt-stress, whereas all were differentially expressed in adapted cells. Interaction with HwHog1 was shown for 36 of the 95 differentially expressed genes. The majority of the identified osmoresponsive and HwHog1-dependent genes in <it>H. werneckii </it>have not been previously reported as Hog1-dependent genes in the salt-sensitive <it>S. cerevisiae</it>. The study further demonstrated the co-occupancy of HwHog1 and RNA polymerase II on the chromatin of 17 up-regulated and 2 down-regulated genes in 4.5 M NaCl-adapted <it>H. werneckii </it>cells.</p> <p>Conclusion</p> <p>Extremely halotolerant <it>H. werneckii </it>represents a suitable and highly relevant organism to study cellular responses to environmental salinity. In comparison with the salt-sensitive <it>S. cerevisiae</it>, this yeast shows a different set of genes being expressed at high salt concentrations and interacting with HwHog1 MAP kinase, suggesting atypical processes deserving of further study.</p>