Studies On The Function Of Histidine Kinase In Penicillium Marneffei

Among the more than 100,000 different species of environmental fungi are six phylogenetically related ascomycetes called the dimorphic fungi:Blastomyces dermatitidis,Coccidioides immitis,Histoplasma capsulatum,Paracoccidioides brasiliensis,Sporothrix schenkii,and Penicillium marneffei.These fungi change morphology once spores are inhaled into the lungs of a mammalian host from hyphal molds in the environment to pathogenic yeast forms.Penicillium marneffei is the only known species of its genus that is temperature-dependent dimorphic.Now,it has emerged as one of the most common opportunistic pathogen causing respiratory,skin and systemic mycosis among immunocompromised and AIDS patients,endemic in South-east Asia and Southern China.To obtain a better understanding of the key elements involved in Penicillium marneffei virulence and to identify possible drug targets,it is necessary to be able to study the important genes which are related to virulence of P.marneffei.In our study, we are interested in the histidine kinase.It is a major signal transduction pathway by which fungus sense and adapt to their environment.Recent work has revealed that the HK gene can regulate diverse processes,including differentiation,chemotaxis, secondary metabolite production,and virulence in plant and animal pathogens.We cloned a novel Penicillium marneffei histidine kinase-PmHHK1 gene from cDNA library and investigated the biological functions using dsRNAi mediated by A. tumefaciens.The activity of RNA interference is under control of promoter xy1P, which can be induced by xylose.The reduction of PmHHK1 activity displays the morphogenesis changes including that sporulation and cell wall composition. Furthermore,several lines of evidence strongly indicate a central regulating role of PmHHK1 in virulence factor.Taken together,we propose that PmHHK1 gene might be involved in regulation of morphogenesis and pathogenicity.Two-component signaling systems are widespread in the eukaryotes outside the animal kingdom, therefore having potential implication for treating fungal diseases.