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Identification and characterization of a novel CprA reductive dehalogenase specific to highly chlorinated phenols from Desulfitobacterium hafniense strain PCP-1.

Abstract：

:Desulfitobacterium hafniense strain PCP-1 reductively dechlorinates pentachlorophenol (PCP) to 3-chlorophenol and a variety of halogenated aromatic compounds at the ortho, meta, and para positions. Several reductive dehalogenases (RDases) are thought to be involved in this cascade of dehalogenation. We partially purified a novel RDase involved in the dechlorination of highly chlorinated phenols from strain PCP-1 cultivated in the presence of 2,4,6-trichlorophenol. The RDase was membrane associated, and the activity was sensitive to oxygen, with a half-life of 128 min upon exposure to air. The pH and temperature optima were 7.0 and 55°C, respectively. Several highly chlorinated phenols were dechlorinated at the ortho positions. The highest dechlorinating activity levels were observed with PCP, 2,3,4,5-tetrachlorophenol, and 2,3,4-trichlorophenol. 3-Chloro-4-hydroxyphenylacetate, 3-chloro-4-hydroxybenzoate, dichlorophenols, and monochlorophenols were not dechlorinated. The apparent K(m) value for PCP was 46.7 μM at a methyl viologen concentration of 2 mM. A mixture of iodopropane and titanium citrate caused a light-reversible inhibition of the dechlorinating activity, suggesting the involvement of a corrinoid cofactor. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the partially purified preparation revealed 2 bands with apparent molecular masses of 42 and 47 kDa. Mass spectrometry analysis using Mascot to search the genome sequence of D. hafniense strain DCB-2 identified the 42-kDa band as NADH-quinone oxidoreductase, subunit D, and the 47-kDa band as the putative chlorophenol RDase CprA3. This is the first report of an RDase with high affinity and high dechlorinating activity toward PCP.

journal_name

Appl Environ Microbiol

journal_title

Applied and environmental microbiology

authors

Bisaillon A,Beaudet R,Lépine F,Déziel E,Villemur R

doi

10.1128/AEM.01362-10

subject

Has Abstract

pub_date

2010-11-01 00:00:00

pages

7536-40

issue

eissn

0099-2240

issn

1098-5336

pii

AEM.01362-10

journal_volume

pub_type

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Identification and characterization of a novel CprA reductive dehalogenase specific to highly chlorinated phenols from Desulfitobacterium hafniense strain PCP-1.