Cryptococcus neoformans can utilize the bacterial melanin precursor homogentisic acid for fungal melanogenesis

Susana Frases, Angela Salazar, Ekaterina Dadachova, Arturo Casadevall

Research output: Contribution to journalArticle

41 Citations (Scopus)

Abstract

Cryptococcus neoformans melanizes in the environment and in mammalian tissues, but the process of melanization in either venue is mysterious given that this microbe produces melanin only from exogenous substrates. Understanding the process of melanization is important because melanization is believed to protect against various stresses in the environment, including UV radiation, and pigment production is associated with virulence. Melanization in C. neoformans requires the availability of diphenolic precursors. In contrast, many bacteria synthesize melanin from homogentisic acid (HGA). We report that C. neoformans strains representing all four serotypes can produce a brown pigment from HGA. The brown pigment was acid resistant and had the electron paramagnetic resonance spectrum of a stable free radical, qualities that identified it as a melanin. Melanin "ghost"-like particles obtained from pigmented C. neoformans cells were hydrophobia, fluorescent under a variety of irradiation wavelengths, negatively charged, insoluble in organic solvents and alcohols, resistant to degradation by strong acids, and vulnerable to bleaching. HGA melanization was laccase dependent and repressed by high concentrations of glucose. The ability of C. neoformans to utilize a bacterial melanin precursor compound suggests a new substrate source for melanization in the environment.

Original languageEnglish (US)
Pages (from-to)615-621
Number of pages7
JournalApplied and Environmental Microbiology
Volume73
Issue number2
DOIs
StatePublished - Jan 2007

Fingerprint

Homogentisic Acid
melanogenesis
melanin
melanization
Cryptococcus neoformans
Melanins
acids
acid
pigment
pigments
substrate
Laccase
Acids
Rabies
Electron Spin Resonance Spectroscopy
free radical
electron spin resonance
bleaching
virulence
laccase

ASJC Scopus subject areas

  • Environmental Science(all)
  • Biotechnology
  • Microbiology

Cite this

Cryptococcus neoformans can utilize the bacterial melanin precursor homogentisic acid for fungal melanogenesis. / Frases, Susana; Salazar, Angela; Dadachova, Ekaterina; Casadevall, Arturo.

In: Applied and Environmental Microbiology, Vol. 73, No. 2, 01.2007, p. 615-621.

Research output: Contribution to journalArticle

Frases, Susana ; Salazar, Angela ; Dadachova, Ekaterina ; Casadevall, Arturo. / Cryptococcus neoformans can utilize the bacterial melanin precursor homogentisic acid for fungal melanogenesis. In: Applied and Environmental Microbiology. 2007 ; Vol. 73, No. 2. pp. 615-621.
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