A Novel Aerobic Degradation Pathway for Thiobencarb Is Initiated by the TmoAB Two-Component Flavin Mononucleotide-Dependent Monooxygenase System in Acidovorax sp. Strain T1

• DOI: 10.1128/aem.01490-17
• Publication Date: 2017-09-23T00:40:28Z
• Authors: Cui-Wei Chu; Bin Liu; Na Li; Shi-Gang Yao; Dan Cheng; Jia-Dong Zhao; Ji-Guo Qiu; Xin Yan; Qin He; Jian He
• Keywords: Flavin mononucleotide; Dioxygenase

Thiobencarb is a thiocarbamate herbicide used in rice paddies worldwide. Microbial degradation plays crucial role the dissipation of thiobencarb environment. However, physiological and genetic mechanisms underlying remain unknown. In this study, novel pathway was proposed Acidovorax sp. strain T1. oxidized cleaved at C-S bond, generating diethylcarbamothioic S-acid 4-chlorobenzaldehyde (4CDA). 4CDA then to 4-chlorobenzoic acid (4CBA) hydrolytically dechlorinated 4-hydroxybenzoic (4HBA). The identification catabolic genes suggested further hydroxylation protocatechuic (PCA) finally through protocatechuate 4,5-dioxygenase pathway. A two-component monooxygenase system identified strain, TmoAB, responsible for initial reaction. TmoA shared 28 32% identity with oxygenase components pyrimidine from Agrobacterium fabrum, alkanesulfonate Pseudomonas savastanoi, dibenzothiophene Rhodococcus TmoB 25 37% reported flavin reductases NADH but not NADPH. TmoAB mononucleotide (FMN)-dependent catalyzed bond cleavage thiobencarb. Introduction tmoAB into cells degradation-deficient mutant T1m restored its ability degrade utilize dehydrogenase gene, tmoC, located 7,129 bp downstream tmoAB, transcription clearly induced by purified TmoC dehydrogenation 4CBA using NAD+ as cofactor. gene cluster complete metabolic also cloned, involvement preliminarily verified transcriptional analysis.IMPORTANCE main factor soil. previous studies, degraded initially via N-deethylation, sulfoxidation, hydroxylation, dechlorination. enzymes involved microbial have been studied. This study revealed new T1 FMN-dependent system, TmoAB. Under TmoAB-mediated catalysis, producing 4CDA. Furthermore, proposed. Our provides physiological, biochemical, foundation microorganism.