Author/Editor		Turk, Martina
Title		Signalna pot odziva HOG na povečano slanost pri halofilni črni kvasovki Hortaea werneckii
Type		monografija
Place		Ljubljana
Publisher		Medicinska fakulteta
Publication year		2003
Volume		str. 91
Language		slo
Abstract		Hortaea werneckii (Dothideales, Ascomycota) is a halophilic melanized yeast-like fungal species, a member of an arbitrary group of so-called black yeasts. It can tolerate extremely high salt concentrations in its environment and can grow at salinities ranging from 0% to a saturated solution of NaCI (32% NaCI (w/v)). It represents a good model organism for studying the adaptations to hypersaline environments. Previous studies have shown that H. werneckii responds to an increased NaCI concentration with changes in the lipid composition which affect membrane fluidity and glycerol accumulation. Glycerol-3-phosphate dehydrogenase is the key enzyme in glycerol production. There are two genes encoding glycerol-3-phosphate dehydrogenase (GPD) in H. werneckii and at least one of them is differentially expressed at increased salinity. We assumed that a pathway similar to the HOG signaling pathway in Saccharomyces cerevisiae is present in H. werneckii and plays an important role in its adaptation to an extremely high salinity. In the present study we investigated whether the hyperosmotic signaling pathway similar to HOG pathway in S. cerevisiae exists in H. werneckii. We demonstrated the presence of MAPK homologue Hoglp and its upstream kinase Pbs2p in H. werneckii. The hypothetical model of interactions among HwHoglp and HwPbs2p under different NaCI concentrations was proposed. A homologue of the HOGI gene, HwHOGl, was isolated and analysed. The existence of only one copy of the HwHOGI gene in the genome of H. werneckii was observed. Its activation by increased salinity is regulated at the post-translational level. We checked the function of kinase HwHoglp with complementation of S. cerevisiae hogld mutant and found that HwHoglp can only partially replace Hoglp. A structural model of kinase HwHoglp in phosphorylated and dephosphorylated form was established. (Abstract truncated at 2000 characters).
Descriptors		PLASMIDS SODIUM CHLORIDE PROTEIN KINASES GLYCEROLPHOSPHATE DEHYDROGENASE ASCOMYCETES BASE SEQUENCE AMINO ACID SEQUENCE SIGNAL TRANSDUCTION DNA, FUNGAL RNA, FUNGAL