Author/Editor		Jeraj, Nataša
Title		Vpliv steroidov na aktivacijo znotrajceličnih signalnih poti pri glivi Rhizopus nigricans
Type		monografija
Place		Ljubljana
Publisher		Univerza v Ljubljani, Medicinska fakulteta
Publication year		2005
Volume		str. 97
Language		slo
Abstract		Several steroids are toxic for the filamentous fungus Rhizopus nigricans and, at high concentrations, inhibit its growth; therefore, a detoxification system has evolved in the fungus that hydroxylates steroids via multienzyme complex with cytochrome P45011a as terminal oxidase. While studing the mechanism of the steroid action in R. nigricans a genomic action of progesterone was discovered that involves intracellular receptors and an induction of 11 ahydroxylation system. Apart from the genomic action progesterone initiates also a nongenomic response through binding to receptors coupled to G proteins found in the plasma membrane; the further signalling pathways are not known. The goal of our study was to examine the nongenomic signalling pathways in R. nigricans induced by steroids and to investigate their impact on growth inhibition. We established that several steroids in 300 uM concentration, in particular progesterone, inhibit growth of the fungus R. nigricans in agar medium. The influence of steroids on the growth is dose-dependent. When cultivated in progesterone-containing mediu the fungus exhibited changes in hyphal morphology-hyphal branching was enhanced and conseguently, colonies were more compact. The specific progesterone binding sites in the plasma membrane were confirmed by binding of fluorescently labelled progesterone to fungal protoplasts. The presence of G proteins Gia-1 (45 kDa) and Gb (34 kDa) in the plasma membrane fraction of R. nigricans was demonstrated. (Abstract truncated at 2000 characters)
Descriptors		RHIZOPUS STEROIDS PROGESTERONE RECEPTORS, PROGESTERONE SIGNAL TRANSDUCTION BINDING SITES GTP-BINDING PROTEINS DNA, COMPLEMENTARY BASE SEQUENCE CYCLIC AMP