Occurrence and expression ofcrdAandcprA5encoding chloroaromatic reductive dehalogenases inDesulfitobacteriumstrains

Abstract

Desulfitobacterium hafniense PCP-1 (formerly frappieri PCP-1) has two reductive dehalogenases (RDases) that have been characterized. One is a membrane-associated 2,4,6-trichlorophenol RDase, which is encoded by crdA, and the other is a 3,5-dichlorophenol RDase encoded by cprA5. In this report, we determined the occurrence of these two RDase genes in seven other Desulfitobacterium strains. The presence or absence of these two RDases may explain the differences in the spectrum of halogenated compounds by these Desulfitobacterium strains. crdA gene sequences were found in all of the tested strains. It was expressed in strain PCP-1 regardless of the absence or presence of chlorophenols in the culture medium. crdA was also expressed in D. hafniense strains DCB-2 and TCE-1. cprA5 was detected only in D. hafniense strains PCP-1, TCP-A, and DCB-2. In these strains, cprA5 transcripts were detected only in the presence of chlorophenols. We also examined the expression of putative cprA RDases (cprA2, cprA3, and cprA4) that were shown to exist in the D. hafniense DCB-2 genome. RT-PCR experiments showed that cprA2, cprA3, and cprA4 were expressed in D. hafniense strains PCP-1, DCB-2, and TCP-A in the presence of chlorophenols. However, contrary to cprA5, these three genes were also expressed in the absence of halogenated compounds in the culture medium.

Identification and Characterization of a Novel CprA Reductive Dehalogenase Specific to Highly Chlorinated Phenols from Desulfitobacterium hafniense Strain PCP-1

“…In previous work, at least two other genes encoding CprAtype RDases were found in strain PCP-1, cprA2 and cprA4 (8,32). Whether or not CprA2 and CprA4 are true RDases is still unknown, but based on the large spectrum of the reductive dehalogenation activity of this strain, it would not be surprising if they are.…”

“…Extraction of D. hafniense strain PCP-1 total DNA was performed according to the method described by Gauthier et al (8). Two oligonucleotides (CprA3_1047F, 5Ј TGC CCG TCT GAA GCC ATA ACT CAT 3Ј, and CprA3_1399R, 5Ј GCA AAG TTT GAG ACC GGC TA 3Ј) were designed based on the D. hafniense strain DCB-2 genome sequence (GenBank accession number CP001336) to amplify the region between nucleotides 1047 and 1399 from the start site of the cprA3 gene.…”

“…The second enzyme, CprA5, catalyzes the meta and para dechlorination of 3,5-DCP and several chlorophenols (28). Three other putative cprA genes were identified in strain PCP-1 (cprA2, cprA3, and cprA4), which suggests that other RDases with different specificities toward halogenated compounds exist in this strain (8,31,32). In this study, we have partially purified and characterized a new CprA-type RDase (CprA3) from strain PCP-1.…”

Desulfitobacterium contributes to the microbial transformation of 2,4,5‐T by methanogenic enrichment cultures from a Vietnamese active landfill

“…An orthologue of RdhA3 from strain DCB‐2 T had overall the highest protein abundance, which was almost 20‐fold higher in the presence of 2,4,5‐T (−/+YE), and was produced as soon as 2,4,5‐TCP started to accumulate (Table 2). RdhA3 and its orthologue CprA5 in D. hafniense strains DCB‐2 T and PCP‐1 were described to be inducible by 3,5‐dichlorophenol (Gauthier et al ., 2006; Bisaillon et al ., 2011; Mac Nelly et al ., 2014). Both enzymes dehalogenated 3,5‐DCP at the meta ‐position and exhibited highest activity with this compound but they also accepted 2,4,5‐TCP as substrate.…”

“…The other detected reductive dehalogenase is an orthologue of Dhaf_0713 or the identical CprA3 of D. hafniense strains DCB‐2 T and PCP‐1 respectively (Table 3). The cprA3 gene was shown to be transcriptionally induced by 2,4,6‐trichlorophenol (Bisaillon et al ., 2011) but was also transcribed in the absence of chlorophenols (Gauthier et al ., 2006). Interestingly, the purified CprA3 of strain PCP‐1 dechlorinated highly chlorinated phenols such as penta‐ and tetrachlorophenols and some trichlorophenols, but not 2,4,5‐TCP (Bisaillon et al ., 2010).…”