Biokemija steroidov pri glivah (Slovene)

According to our previous results the existence of steroid hormone signalling system in the filamentous fungus Cochliobolus lunatus was suggested. In the mentioned ascomycetous fungus we were able to prove the presence of the three components of the system: 17beta-hydroxysteroid dehydrogenase (17beta-HSD), androgen binding proteins and steroid hormone signalling molecule testosterone. Our main interest was focused to the characterization of the individual components, especially to 17beta-hydroxysteroid dehydrogenase in order to find out their role in the fungus. Later the study of the system was extended to basidiomycetous fungus Pleurotus ostreatus. Some differences between the individual components of the two fungal steroid hormone systems were detected. Since we are interested in the distribution of the individual components of the system in eucaryotic microorganisms 17beta-HSD activity will also be tested in the representatives of halophilic and mesophilic yeasts. For our future experiments, a more detailed characterization of the mentioned 17beta-HSD is planned; e.g. kinetic study of the recombinant 17beta-HSD from Cochliobolus lunatus and the study of 17beta-HSD from Pleurotus ostreatus and other fungi by modern mass spectrometry techniques. Because of its suggested involvment in beta-oxidation of fatty acids and thus possible homology to 17beta-HSD type IV beta-hydroxybutyryl CoA dehydrogenase from Pleurotus ostreatus will be studied as well. The results will contribute to the elucidation of the role of 17beta-HSD in eucaryotic microorganisms and the evolution of 17beta-HSD.