Role of HogA and SskB protein kinases in mycotoxin production in the Filamentous Fungus Aspergillus nidulans
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Aspergillus nidulans is a filamentous fungus that is often used as a model organism in genetics and molecular biology studies. The species has a well- characterized life-cycle and its genome has been sequenced. Aspergillus species are commonly found in the environment. Some species can cause health problems in humans. Some Aspergillus species produce aflatoxin, a toxic compound that causes acute necrosis, cirrhosis, and carcinoma of the liver in some animal species and can potentially cause similar symptoms in humans (Center for Integrated Fungal Research, 2005). A. nidulans produces the carcinogenic mycotoxin sterigmatocystin (ST), a precursor in the aflatoxin biosynthetic pathway (Adams, 1994). The focus of this project is to characterize the possible involvement of two A. nidulans stress- response protein kinases in the regulation of mycotoxin production. The two protein kinases under study are HogA and SskB. They are part of a phosphorelay system that senses osmotic and oxidative stress and triggers an adaptive response to these stimuli (Miskei, 2009). Our results suggest that the HogA pathway negatively regulates ST biosynthesis. This is the first study of the connection between elements of the HogA response pathway and the regulation of ST production.