2-Haloacrylate Hydratase, a New Class of Flavoenzyme That Catalyzes the Addition of Water to the Substrate for Dehalogenation

Abstract

Enzymes catalyzing the conversion of organohalogen compounds are useful in the chemical industry and environmental technology. Here we report the occurrence of a new reduced flavin adenine dinucleotide (FAD) (FADH 2 )-dependent enzyme that catalyzes the removal of a halogen atom from an unsaturated aliphatic organohalogen compound by the addition of a water molecule to the substrate. A soil bacterium, Pseudomonas sp. strain YL, inducibly produced a protein named Caa67 YL when the cells were grown on 2-chloroacrylate (2-CAA). The caa67 YL gene encoded a protein of 547 amino acid residues (M r of 59,301), which shared weak but significant sequence similarity with various flavoenzymes and contained a nucleotide-binding motif. We found that 2-CAA is converted into pyruvate when the reaction was carried out with purified Caa67 YL

D-Specific Dehalogenases, a Review

“…enzymes involved in the conversion of organohalogen compounds have potential applications in environmental technologies and the chemical industry (18,23,24). For the catabolism of recalcitrant halogenated organic compounds in the biosphere, dehalogenation is regarded as the key first step (12).…”

Novel Dehalogenase Mechanism for 2,3-Dichloro-1-Propanol Utilization in Pseudomonas putida Strain MC4

“…Further degradation of 2-chloroacrylic acid was not studied in MC4, but known pathways are hydrolytic dechlorination of 2-chloroacrylic acid, which yields pyruvate (32), or reduction of 2-chloroacrylic acid to 2-chloropropionic acid, which can be dehalogenated to lactate (35).…”

A Mechanistic Analysis of Enzymatic Degradation of Organohalogen Compounds

“…YL apparently does not have 2-haloacrylate reductase, as judged by the results of twodimensional PAGE analysis of the proteins and genomic DNA analysis. 62) Thus 2-haloacrylate hydratase probably plays a major role in the metabolism of 2-CAA in Pseudomonas sp. YL.…”

“…YL, as described in section V below. 62) 2-Haloacrylate reductase is useful in the production of L-2-chloropropionate, a building block in the synthesis of aryloxyphenoxypropionate herbicides.…”

“…62) A homology search revealed that CAA67 YL shares 84.6% sequence identity with CAA67 from another 2-CAA-utilizable bacterium, Burkholderia sp. WS (referred to as CAA67 WS in this section to avoid confusion).…”