| Abstract
| - Melanin is a virulence factor for many pathogenic fungal species, including Cryptococcusneoformans. Melanin is deposited in the cell wall, and melanin isolated from this fungus retains the shapeof the cells, resulting in hollow spheres called “ghosts”. In this study, atomic force, scanning electron,and transmission electron microscopy revealed that melanin ghosts are covered with roughly sphericalgranular particles approximately 40−130 nm in diameter, and that the melanin is arranged in multipleconcentric layers. Nuclear magnetic resonance cryoporometry indicated melanin ghosts contain pores withdiameters between 1 and 4 nm, in addition to a small number of pores with diameters near 30 nm. Bindingof the antibodies to melanin reduced the apparent measured volume of these pores, suggesting a mechanismfor their antifungal effect. We propose a model of cryptococcal melanin structure whereby the melaningranules are held together in layers. This structural model has implications for cell division, cell wallremodeling, and antifungal drug discovery.
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