DOPA and DHN pathway orchestrate melanin synthesis in Aspergillus species

Melanins are high molecular weight hydrophobic pigments that have been studied for their role in the virulence of fungal pathogens. We investigated the amount and type of melanin in 20 isolates of Aspergillus spp.; A. niger (n = 3), A. flavus (n = 5), A. tamarii (n = 3), A. terreus (n = 3), A. tubin...

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Bibliographic Details
Published in:Medical mycology (Oxford) 2014-01, Vol.52 (1), p.10-18
Main Authors: Pal, Anuradha K., Gajjar, Devarshi U., Vasavada, Abhay R.
Format: Article
Language:English
Subjects:
Aspergillus
Aspergillus - classification
Aspergillus - genetics
Aspergillus - metabolism
Aspergillus flavus
Dihydroxyphenylalanine - metabolism
DNA, Intergenic - chemistry
DNA, Intergenic - genetics
Melanins - biosynthesis
Metabolic Networks and Pathways
Molecular Sequence Data
Naphthols - metabolism
Sequence Analysis, DNA
Spectrum Analysis
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Summary:Melanins are high molecular weight hydrophobic pigments that have been studied for their role in the virulence of fungal pathogens. We investigated the amount and type of melanin in 20 isolates of Aspergillus spp.; A. niger (n = 3), A. flavus (n = 5), A. tamarii (n = 3), A. terreus (n = 3), A. tubingensis (n = 3), A. sydowii (n = 3). Aspergillus spp. were identified by sequencing the internal transcribed spacer (ITS) region. Extraction of melanin from culture filtrate and fungal biomass was done and followed by qualitative and quantitative analysis of melanin pigment. Ultraviolet (UV), Fourier transformed infrared (FT-IR), and electron paramagnetic resonance (EPR) spectra analyses confirmed the presence of melanin. The melanin pathway was studied by analyzing the effects of inhibitors; kojic acid, tropolone, phthalide, and tricyclazole. The results indicate that in A. niger and A. tubingensis melanin was found in both culture filtrate and fungal biomass. For A. tamarii and A. flavus melanin was extracted from biomass only, whereas melanin was found only in culture filtrate for A. terreus. A negligible amount of melanin was found in A. sydowii. The maximum amount of melanin from culture filtrate and fungal biomass was found in A. niger and A. tamarrii, respectively. The DOPA (3,4-dihydroxyphenylalanine) pathway produces melanin in A. niger, A. tamarii and A. flavus, whereas the DHN (1,8-dihydroxynaphthalene) pathway produces melanin in A. tubingensis and A. terreus. It can be concluded that the amount and type of melanin in aspergilli largely differ from species to species.
ISSN:1369-3786
1460-2709
DOI:10.3109/13693786.2013.826879