Premium
Melanization of flavonoids by fungal and bacterial laccases
Author(s) -
Fowler Zachary L.,
Baron Christopher M.,
Panepinto John C.,
Koffas Mattheos A. G.
Publication year - 2011
Publication title -
yeast
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.923
H-Index - 102
eISSN - 1097-0061
pISSN - 0749-503X
DOI - 10.1002/yea.1829
Subject(s) - laccase , biology , melanin , flavonoid , cryptococcus neoformans , pigment , bacillus subtilis , polyphenol , yeast , resveratrol , biochemistry , microbiology and biotechnology , bacteria , enzyme , chemistry , genetics , organic chemistry , antioxidant
Laccase activity in plants results in the formation of a number of brown pigments, often referred to as tannins. Laccase‐dependent pigment production is also catalogued in numerous fungal and bacterial species. The laccase of the haploid yeast Cryptococcus neoformans forms melanin‐like pigmentation outside the cell wall in the presence of exogenous substrates. While this process is a contributing factor to its virulence in humans, the evolutionary intent for the laccase function remains a mystery. We show here that C. neoformans and Bacillus subtilis have the ability to create melanin‐like pigments from a variety of flavonoid molecules across a range of conformations, preferring those with 3′,4′‐dihydroxylations. Since flavonoids are ubiquitous plant molecules and often‐considered antimicrobial agents, we postulate that they are the intended natural targets of laccase activity and result in the formation of a defensive melanin‐like coat. These results suggests a new mechanism by which flavonoid‐melanin formation may occur, using not only A‐ and C‐ring linkages, but also monomer links through the B‐ring of the flavonoid structure. We also show that resveratrol and other non‐ and mono‐hydroxylated polyphenol substrates have the ability to restrict pigment formation and may be potent inhibitors of laccase activity. Copyright © 2010 John Wiley & Sons, Ltd.