Identification and modification of biphenyl dioxygenase sequences that determine the specificity of polychlorinated biphenyl degradation.
AUTOR(ES)
Mondello, F J
RESUMO
The polychlorinated biphenyl (PCB) congener specificities and partial BphA sequences of biphenyl dioxygenase were determined for a set of PCB-degrading bacteria. The strains examined were categorized into two groups based on their ability to degrade 17 PCB congeners. Strains that degraded a broad range of PCBs but had relatively weak activity against di-para-substituted PCBs were designated as having an LB400-type specificity. Strains designated as having a KF707-type specificity degraded a much narrower range of PCBs but had strong activity against certain di-para-substituted congeners. BphA protein sequence comparisons between these two types of strains identified four regions (designated I, II, III, and IV) in which specific sequences were consistently associated with either broad or narrow PCB substrate specificity. The dramatic differences in substrate specificity between LB400 and KF707 appear to result primarily from a combination of mutations in regions III and IV. Altering these regions in the LB400 BphA subunit to correspond to those in the KF707 sequence produced a narrow substrate specificity very similar to that of KF707. Some individual mutations within region III alone were found to improve PCB degradative activity, especially for di-para-substituted congeners. However, the greatest improvements in activity resulted from multiple amino acid modifications in region III, suggesting that the effects of these mutations are cooperative. These results demonstrate the ability to significantly improve PCB oxidative activity through sequence modifications of biphenyl dioxygenase.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=168606Documentos Relacionados
- Cloning and expression in Escherichia coli of Pseudomonas strain LB400 genes encoding polychlorinated biphenyl degradation.
- Identification of the bphA4 gene encoding ferredoxin reductase involved in biphenyl and polychlorinated biphenyl degradation in Pseudomonas sp. strain KKS102.
- Novel Approach to the Improvement of Biphenyl and Polychlorinated Biphenyl Degradation Activity: Promoter Implantation by Homologous Recombination
- Degradation of Polychlorinated Biphenyl Metabolites by Naphthalene-Catabolizing Enzymes
- Nucleotide sequencing and transcriptional mapping of the genes encoding biphenyl dioxygenase, a multicomponent polychlorinated-biphenyl-degrading enzyme in Pseudomonas strain LB400.
