title: Detection of DOPA-melanin in the dimorphic fungal pathogen Penicillium marneffei and its effect on macrophage phagocytosis in vitro.
abstract: The fungal pathogen Penicillium marneffei produces melanin-like pigment in vitro. The synthetic pathway of melanin and its possible influence in the protective yeast cells surviving within macrophage cells are not known. In this work, P. marneffei produced brown black pigment in the presence of L-DOPA and black particles were extracted from yeast cells treated with proteolytic enzymes, denaturant and concentrated hot acid. Kojic acid inhibited the brown-black pigment production of P. marneffei yeast grown on brain heart infusion agar. Transmitting electron microscopy showed spherical granular electron-dense particles with an average diameter of 100 nm in a beaded arrangement in the innermost cell wall. Electron-paramagnetic resonance revealed that the black particles contain a stable free radical compound. The UV-visible and Fourier transform infrared spectra of particles extracted from P. marneffei and synthetic DOPA-melanin showed a high degree of similarity. Melanized yeast cells decreased phagocytosis by macrophage cells and increased resistance to intracellular digestion in vitro. These results indicate that P. marneffei can synthesize DOPA-melanin or melanin-like compounds in vitro and suggest that the DOPA-melanin pathway is associated with cell wall structure and enhances the resistance to phagocytosis by macrophages.
authors.affiliation: Department of Dermatology and Venereology, First Affiliated Hospital, Guangxi Medical University, Nanning, China.
authors.forename: Donghua
authors.initials: D
authors.lastname: Liu
authors.affiliation: Department of Dermatology and Venereology, First Affiliated Hospital, Guangxi Medical University, Nanning, China.
authors.forename: Lili
authors.initials: L
authors.lastname: Wei
authors.affiliation: Department of Dermatology and Venereology, First Affiliated Hospital, Guangxi Medical University, Nanning, China.
authors.forename: Ting
authors.initials: T
authors.lastname: Guo
authors.affiliation: Department of Dermatology and Venereology, First Affiliated Hospital, Guangxi Medical University, Nanning, China.
authors.forename: Weifen
authors.initials: W
authors.lastname: Tan
mesh_terms: D004295:Dihydroxyphenylalanine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D004578:Electron Spin Resonance Spectroscopy; D008855:Microscopy, Electron, Scanning; D010407:Penicillium / Q000378:metabolism* / Q000472:pathogenicity*; D010587:Phagocytosis / Q000187:drug effects*
chemical_list: D004295:Dihydroxyphenylalanine; C040616:DOPA melanin