The interface of mycology and endocrinology

Message molecules such as hormones or pheromones have been described in non-pathogenic fungi and largely control mating. In one instance, a fungal hormone has a sequence homologous with a mammalian hormone, binds to a mammalian receptor and produces a functional response in a mammalian cell. Some mammalian hormones have also been shown to inhibit or stimulate pathogenic and non-pathogenic fungi, although until recently fungal binders (receptors) had not been demonstrated and the concentrations studied were not physiologic. We studied Paracoccidioides brasiliensis, for human sex hormone binding and functional effect, because of the predominance of paracoccidioidomycosis in males. We found a cytosolic 17-beta-estradiol (E2) binding protein in mycelia with Kd = 13 nM and a capacity of 78 fmol mg-1 protein. E2 prevents mycelium-to-yeast or conidium-to-yeast conversion in vitro at close to physiologic concentrations. In vivo this action could inhibit or delay conversion to the pathogenic form, allowing sufficient time for stimulation of an effective immune response. More recent studies have demonstrated E2 block of fungal proteins associated with mycelium-to-yeast conversion, and effects on methionine uptake. In other studies, a progesterone binder in dermatophytes has been described. Progesterone inhibits the growth of these fungi, a finding which may also relate to the relative resistance of females to dermatophyte infection. A corticosteroid-binding protein has been described in Candida species.(ABSTRACT TRUNCATED AT 250 WORDS)