Characterization of a novel angular dioxygenase from fluorene-degrading Sphingomonas sp. strain LB126

TL;DR

This study characterizes a novel angular dioxygenase from Sphingomonas sp. LB126 that oxidizes fluorene and related compounds, revealing its substrate specificity and potential for bioremediation.

Contribution

It identifies and characterizes a new angular dioxygenase enzyme with unique substrate oxidation capabilities from Sphingomonas sp. LB126.

Findings

FlnA1A2 oxidizes fluorene, fluorenol, fluorenone, dibenzofuran, and dibenzo-p-dioxin.

FlnA1A2 prefers fluorene and phenanthrene as substrates.

The enzyme shows broader substrate range than similar dioxygenases.

Abstract

In this study, the genes involved in the initial attack on fluorene by Sphingomonas sp. LB126 were investigated. The ? and ? subunits of a dioxygenase complex (FlnA1A2), showing 63% and 51% sequence identity respectively, with the subunits of an angular dioxygenase from Gram-positive Terrabacter sp. DBF63, were identified. When overexpressed in E. coli, FlnA1A2 was responsible for the angular oxidation of fluorene, fluorenol, fluorenone, dibenzofuran and dibenzo-p-dioxin. Moreover, FlnA1A2 was able to oxidize polycyclic aromatic hydrocarbons and heteroaromatics, some of which were not oxidized by the dioxygenase from Terrabacter sp. DBF63. Quantification of resulting oxidation products showed that fluorene and phenanthrene were preferred substrates.