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Regioselective Dichlorination of a Non‐Activated Aliphatic Carbon Atom and Phenolic Bismethylation by a Multifunctional Fungal Flavoenzyme
Author(s) -
Chankhamjon Pranatchareeya,
Tsunematsu Yuta,
IshidaIto Mie,
Sasa Yuzuka,
Meyer Florian,
BoettgerSchmidt Daniela,
Urbansky Barbara,
Menzel KlausDieter,
Scherlach Kirstin,
Watanabe Kenji,
Hertweck Christian
Publication year - 2016
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201604516
Subject(s) - regioselectivity , chemistry , halogenation , geminal , enzyme , substrate (aquarium) , stereochemistry , organic chemistry , biology , catalysis , ecology
The regioselective functionalization of non‐activated carbon atoms such as aliphatic halogenation is a major synthetic challenge. A novel multifunctional enzyme catalyzing the geminal dichlorination of a methyl group was discovered in Aspergillus oryzae (Koji mold), an important fungus that is widely used for Asian food fermentation. A biosynthetic pathway encoded on two different chromosomes yields mono‐ and dichlorinated polyketides (diaporthin derivatives), including the cytotoxic dichlorodiaporthin as the main product. Bioinformatic analyses and functional genetics revealed an unprecedented hybrid enzyme (AoiQ) with two functional domains, one for halogenation and one for O‐methylation. AoiQ was successfully reconstituted in vivo and in vitro, unequivocally showing that this FADH 2 ‐dependent enzyme is uniquely capable of the stepwise gem ‐dichlorination of a non‐activated carbon atom on a freestanding substrate. Genome mining indicated that related hybrid enzymes are encoded in cryptic gene clusters in numerous ecologically relevant fungi.