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Two novel decarboxylase genes play a key role in the stereospecific catabolism of dehydrodiconiferyl alcohol in Sphingobium sp. strain SYK‐6
Author(s) -
Takahashi Kenji,
Miyake Kyohei,
Hishiyama Shojiro,
Kamimura Naofumi,
Masai Eiji
Publication year - 2018
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/1462-2920.14099
Subject(s) - stereochemistry , catabolism , decarboxylation , biology , biochemistry , side chain , alcohol , strain (injury) , enzyme , chemistry , catalysis , organic chemistry , polymer , anatomy
Summary Sphingobium sp. strain SYK‐6 is able to use a phenylcoumaran‐type biaryl, dehydrodiconiferyl alcohol (DCA), as a sole source of carbon and energy. In SYK‐6 cells, the alcohol group of the B‐ring side chain of DCA was first oxidized to the carboxyl group, and then the alcohol group of the A‐ring side chain was oxidized to generate 5‐(2‐carboxyvinyl)‐2‐(4‐hydroxy‐3‐methoxyphenyl)‐7‐methoxy‐2,3‐dihydrobenzofuran‐3‐carboxylate (DCA‐CC). We identified phcF , phcG and phcH , which conferred the ability to convert DCA‐CC into 3‐(4‐hydroxy‐3‐(4‐hydroxy‐3‐methoxystyryl)‐5‐methoxyphenyl)acrylate (DCA‐S) in a host strain. These genes exhibited no significant sequence similarity with known enzyme genes, whereas phcF and phcG , which contain a DUF3237 domain of unknown function, showed 32% amino acid sequence identity with each other. The DCA‐CC conversion activities were markedly decreased by disruption of phcF and phcG , indicating that phcF and phcG play dominant roles in the conversion of DCA‐CC. Purified PhcF and PhcG catalysed the decarboxylation of the A‐ring side chain of DCA‐CC, producing DCA‐S, and showed enantiospecificity towards (+)‐ and (–)‐DCA‐CC respectively. PhcF and PhcG formed homotrimers, and their K m for DCA‐CC were determined to be 84 μM and 103 μM, and V max were 307 μmol⋅min −1 ⋅mg −1 and 137 μmol⋅min −1 ⋅mg −1 respectively. In conclusion, PhcF and PhcG are enantiospecific decarboxylases involved in phenylcoumaran catabolism.