Dataset Information

Functional analyses of a variety of chimeric dioxygenases constructed from two biphenyl dioxygenases that are similar structurally but different functionally.

ABSTRACT: The biphenyl dioxygenases (BP Dox) of strains Pseudomonas pseudoalcaligenes KF707 and Pseudomonas cepacia LB400 exhibit a distinct difference in substrate ranges of polychlorinated biphenyls (PCB) despite nearly identical amino acid sequences. The range of congeners oxidized by LB400 BP Dox is much wider than that oxidized by KF707 BP Dox. The PCB degradation abilities of these BP Dox were highly dependent on the recognition of the chlorinated rings and the sites of oxygen activation. The KF707 BP Dox recognized primarily the 4'-chlorinated ring (97%) of 2,5,4'-trichlorobiphenyl and introduced molecular oxygen at the 2',3' position. The LB400 BP Dox recognized primarily the 2,5-dichlorinated ring (95%) of the same compound and introduced O2 at the 3,4 position. It was confirmed that the BphA1 subunit (iron-sulfur protein of terminal dioxygenase encoded by bphA1) plays a crucial role in determining the substrate selectivity. We constructed a variety of chimeric bphA1 genes by exchanging four common restriction fragments between the KF707 bphA1 and the LB400 bphA1. Observation of Escherichia coli cells expressing various chimeric BP Dox revealed that a relatively small number of amino acids in the carboxy-terminal half (among 20 different amino acids in total) are involved in the recognition of the chlorinated ring and the sites of dioxygenation and thereby are responsible for the degradation of PCB. The site-directed mutagenesis of Thr-376 (KF707) to Asn-376 (LB400) in KF707 BP Dox resulted in the expansion of the range of biodegradable PCB congeners.

SUBMITTER: Kimura N

PROVIDER: S-EPMC179202 | biostudies-other | 1997 Jun

REPOSITORIES: biostudies-other

ACCESS DATA

Publications

Functional analyses of a variety of chimeric dioxygenases constructed from two biphenyl dioxygenases that are similar structurally but different functionally.

Kimura N N Nishi A A Goto M M Furukawa K K

Journal of bacteriology 19970601 12

The biphenyl dioxygenases (BP Dox) of strains Pseudomonas pseudoalcaligenes KF707 and Pseudomonas cepacia LB400 exhibit a distinct difference in substrate ranges of polychlorinated biphenyls (PCB) despite nearly identical amino acid sequences. The range of congeners oxidized by LB400 BP Dox is much wider than that oxidized by KF707 BP Dox. The PCB degradation abilities of these BP Dox were highly dependent on the recognition of the chlorinated rings and the sites of oxygen activation. The KF707 ...[more]

PMID: 9190809

Similar Datasets

Project description:In this work, we examined the profile of metabolites produced from the doubly para-substituted biphenyl analogs 4,4'-dihydroxybiphenyl, 4-hydroxy-4'-chlorobiphenyl, 3-hydroxy-4,4'-dichlorobiphenyl, and 3,3'-dihydroxy-4,4'-chlorobiphenyl by biphenyl-induced Pandoraea pnomenusa B356 and by its biphenyl dioxygenase (BPDO). 4-Hydroxy-4'-chlorobiphenyl was hydroxylated principally through a 2,3-dioxygenation of the hydroxylated ring to generate 2,3-dihydro-2,3,4-trihydroxy-4'-chlorobiphenyl and 3,4-dihydroxy-4'-chlorobiphenyl after the removal of water. The former was further oxidized by the biphenyl dioxygenase to produce ultimately 3,4,5-trihydroxy-4'-chlorobiphenyl, a dead-end metabolite. 3-Hydroxy-4,4'-dichlorobiphenyl was oxygenated on both rings. Hydroxylation of the nonhydroxylated ring generated 2,3,3'-trihydroxy-4'-chlorobiphenyl with concomitant dechlorination, and 2,3,3'-trihydroxy-4'-chlorobiphenyl was ultimately metabolized to 2-hydroxy-4-chlorobenzoate, but hydroxylation of the hydroxylated ring generated dead-end metabolites. 3,3'-Dihydroxy-4,4'-dichlorobiphenyl was principally metabolized through a 2,3-dioxygenation to generate 2,3-dihydro-2,3,3'-trihydroxy-4,4'-dichlorobiphenyl, which was ultimately converted to 3-hydroxy-4-chlorobenzoate. Similar metabolites were produced when the biphenyl dioxygenase of Burkholderia xenovorans LB400 was used to catalyze the reactions, except that for the three substrates used, the BPDO of LB400 was less efficient than that of B356, and unlike that of B356, it was unable to further oxidize the initial reaction products. Together the data show that BPDO oxidation of doubly para-substituted hydroxychlorobiphenyls may generate nonnegligible amounts of dead-end metabolites. Therefore, biphenyl dioxygenase could produce metabolites other than those expected, corresponding to dihydrodihydroxy metabolites from initial doubly para-substituted substrates. This finding shows that a clear picture of the fate of polychlorinated biphenyls in contaminated sites will require more insights into the bacterial metabolism of hydroxychlorobiphenyls and the chemistry of the dihydrodihydroxylated metabolites derived from them.

Dataset Information

Functional analyses of a variety of chimeric dioxygenases constructed from two biphenyl dioxygenases that are similar structurally but different functionally.

Publications

Functional analyses of a variety of chimeric dioxygenases constructed from two biphenyl dioxygenases that are similar structurally but different functionally.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets