Mechanisms of copper and zinc homeostasis in pathogenic black fungi

Abstract

Black fungi comprise a diverse group of melanized microorganisms, many of which are able to infect humans. One of the recognized diseases that arise with black fungi infection is chromoblastomycosis, a neglected implantation mycosis. Considering their ecology, black fungi may face conditions with distinct metal availability. Zinc and copper are essential transition metals, which become toxic in excess. During the interaction with host, fungi may face either metal deprivation or poisoning. Here we report an in silico analysis of four black fungi genomes concerning zinc and copper homeostasis. Overall, these organisms share apparatus of metal uptake, storage and detoxification with other pathogenic and non-pathogenic fungi. Genes coding plasma membrane and organelle transporters, as well as metal binding proteins were identified. Althought putatives zinc and copper responsive transcription factors have been found in the analyzed genomes, remarkable structural differences were perceived when compared to the already characterized regulators. Black fungi may harbor unique features concerning the regulation of zinc and copper homeostasis, which is probably a result of the niches they can inhabit. The data provided here add knowlegde to a still unexplored aspect of black fungi biology that may be useful in the understanding of their pathogenicity.

Keywords: Black fungus pathogenesis; Chromoblastomycosis; Fungal virulence; Metal sensing.