Biphenyl-inducible Promoters in a Polychlorinated Biphenyl-degrading Bacterium,<i>Rhodococcus</i>sp. RHA1

Takeda, Hisashi; Hara, Naho; Sakai, Masayuki; Yamada, Akira; Miyauchi, Keisuke; Masai, Eiji; Fukuda, Masao

doi:10.1271/bbb.68.1249

Cited by 31 publications

(31 citation statements)

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“…The current study indicates that during growth on styrene, only the bphABC genes are induced. The expression of the bph and etb genes is regulated by two-component regulatory systems in which BphS phosphorylates BphT in response to the presence of a range of aromatic compounds (51,52). Phosphorylated BphT promotes transcription from at least five bph and etb promoters.…”

Section: Discussionmentioning

confidence: 99%

Roles of Ring-Hydroxylating Dioxygenases in Styrene and Benzene Catabolism inRhodococcus jostiiRHA1

et al. 2008

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Proteomics and targeted gene disruption were used to investigate the catabolism of benzene, styrene, biphenyl, and ethylbenzene in Rhodococcus jostii RHA1, a well-studied soil bacterium whose potent polychlorinated biphenyl (PCB)-transforming properties are partly due to the presence of the related Bph and Etb pathways. Of 151 identified proteins, 22 Bph/Etb proteins were among the most abundant in biphenyl-, ethylbenzene-, benzene-, and styrene-grown cells. Cells grown on biphenyl, ethylbenzene, or benzene contained both Bph and Etb enzymes and at least two sets of lower Bph pathway enzymes. By contrast, styrene-grown cells contained no Etb enzymes and only one set of lower Bph pathway enzymes. Gene disruption established that biphenyl dioxygenase (BPDO) was essential for growth of RHA1 on benzene or styrene but that ethylbenzene dioxygenase (EBDO) was not required for growth on any of the tested substrates. Moreover, whole-cell assays of the ⌬bphAa and etbAa1::cmrA etbAa2::aphII mutants demonstrated that while both dioxygenases preferentially transformed biphenyl, only BPDO transformed styrene. Deletion of pcaL of the ␤-ketoadipate pathway disrupted growth on benzene but not other substrates. Thus, styrene and benzene are degraded via meta-and ortho-cleavage, respectively. Finally, catalases were more abundant during growth on nonpolar aromatic compounds than on aromatic acids. This suggests that the relaxed specificities of BPDO and EBDO that enable RHA1 to grow on a range of compounds come at the cost of increased uncoupling during the latter's initial transformation. The stress response may augment RHA1's ability to degrade PCBs and other pollutants that induce similar uncoupling.Rhodococci are mycolic acid-producing actinomycetes that degrade a wide variety of organic compounds (13). These catabolic capabilities are of interest for a range of bioremediation and biocatalytic applications (53). To better understand the physiology and metabolism of this important genus, we have conducted genomic studies of Rhodococcus jostii RHA1 (formerly Rhodococcus sp. strain RHA1, the species was recently identified by A. L. Jones and M. Goodfellow [personal communication]), a strain that possesses an exceptional ability to aerobically degrade polychlorinated biphenyls (PCBs) (47). Annotation of the 9.7-Mb RHA1 genome (31; http://www .rhodococcus.ca) predicted over 200 oxygenases and 30 pathways involved in the catabolism of aromatic compounds. Transcriptomic and proteomic studies have revealed a number of unique features of RHA1 metabolism, including a novel nitrile hydratase (37) and multiple steroid-degrading pathways (54).RHA1 transforms PCBs using the homologous Bph and Etb pathways (19), so named for their presumed respective specificities for biphenyl (47) and ethylbenzene (16, 57), respectively. The pathways utilize a meta-cleavage strategy in which vicinal dihydroxylation of an aromatic ring enables oxygenolytic extradiol (or meta) ring opening (Fig.

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Section: Discussionmentioning

confidence: 99%

Roles of Ring-Hydroxylating Dioxygenases in Styrene and Benzene Catabolism inRhodococcus jostiiRHA1

et al. 2008

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“…The involvement of BphS2T2 in the transcriptional induction of bphAap, etbAa1p, etbAa2p, etbAdp, and etbD1p was examined, because these five promoters are under the control of bphS1T1 (37). The bphS2T2 gene fragment was inserted into a recombinant plasmid containing each fragment of these promoters in a promoter probe vector, pKLA1 (46).…”

Section: Resultsmentioning

confidence: 99%

“…The genes etbD1 and etbD2 encode 2-hydroxy-6-oxohepta-2,4-dienoate hydrolase, which has little activity toward 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoate, a meta-cleavage intermediate product of biphenyl (10,46), and the genes etbAa1Ab1 and etbAa2Ab2 are duplicated genes with the same amino acid sequences. The expression of these genes is simultaneously induced from the promoters of bphAa, etbAa1, etbAa2, etbAd, and etbD1 (bphAap, etbAa1p, etbAa2p, etbAdp, and etbD1p, respectively) in the presence of aromatic compounds, including biphenyl and ethylbenzene (37,38,46). All these promoters are under the control of a two-component system encoded by bphS and bphT, which encode the sensor histidine kinase and response regulator, respectively, since the heterologous expression of bphST in Rhodococcus erythropolis IAM1399 has been shown to promote transcriptional activation of bphAap, etbAa1p, etbAa2p, etbAdp, and etbD1p connected to the luxAB luciferase reporter genes in the presence of biphenyl (37,38).…”

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“…The expression of these genes is simultaneously induced from the promoters of bphAa, etbAa1, etbAa2, etbAd, and etbD1 (bphAap, etbAa1p, etbAa2p, etbAdp, and etbD1p, respectively) in the presence of aromatic compounds, including biphenyl and ethylbenzene (37,38,46). All these promoters are under the control of a two-component system encoded by bphS and bphT, which encode the sensor histidine kinase and response regulator, respectively, since the heterologous expression of bphST in Rhodococcus erythropolis IAM1399 has been shown to promote transcriptional activation of bphAap, etbAa1p, etbAa2p, etbAdp, and etbD1p connected to the luxAB luciferase reporter genes in the presence of biphenyl (37,38). Disruption of the bphS gene in RHA1 resulted in growth deficiency on biphenyl, suggesting that the bphS-dependent two-component system is solely responsible for the induction of biphenyl degradation gene promoters by biphenyl.…”

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Dual Two-Component Regulatory Systems Are Involved in Aromatic Compound Degradation in a Polychlorinated-Biphenyl Degrader, Rhodococcus jostii RHA1

et al. 2010

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A Gram-positive polychlorinated-biphenyl (PCB) degrader, Rhodococcus jostii RHA1, degrades PCBs by cometabolism with biphenyl. A two-component BphS1T1 system encoded by bphS1 and bphT1 (formerly bphS and bphT) is responsible for the transcription induction of the five gene clusters, bphAaAbAcAdC1B1, etbAa1Ab1CbphD1, etbAa2Ab2AcD2, etbAdbphB2, and etbD1, which constitute multiple enzyme systems for biphenyl/PCB degradation. The bphS2 and bphT2 genes, which encode BphS2 and BphT2, virtually identical to BphS1 (92%) and BphT1 (97%), respectively, were characterized. BphS2T2 induced the activation of the bphAa promoter in a host, Rhodococcus erythropolis IAM1399, in the presence of a variety of aromatics, including benzene, toluene, ethylbenzene, xylenes, isopropylbenzene, and chlorinated benzenes, as effectively as BphS1T1. The substrate spectrum of BphS2T2 was the same as that of BphS1T1, except for biphenyl, which is a substrate only for BphS1T1. BphS2T2 activated transcription from the five promoters of biphenyl/PCB degradation enzyme gene clusters as effectively as BphS1T1. The targeted disruptions of the bphS1, bphS2, bphT1, and bphT2 genes indicated that all these genes are involved in the growth of RHA1 on aromatic compounds. The hybrid system with bphS1 and bphT2 and that with bphS2 and bphT1 were constructed, and both systems conducted induced activation of the bphAa promoter, indicating cross-communication. These results indicated that RHA1 employs not only multiple enzyme systems, but also dual regulatory systems for biphenyl/PCB degradation. Comparison of the sequences, including bphS2T2, with the bphS1T1-containing sequences and the corresponding sequences in other rhodococcal degraders suggests that bphS2T2 might have originated from bphS1T1.

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“…Rhodococcus strains: transcriptomic and proteomic techniques [280][281][282], analyses of regulator-operator interactions [283,284], studies of transcription using reporters [284][285][286][287], development of systems for the overexpression of genes involved in key catabolic pathways and enzymes [288][289][290][291]. Lastly, the first complete Rhodococcus genome sequences have come available, revealing very large genome sizes, partly owing to the presence of (multiple) large ( and Rhodococcus erythropolis PR4 [293] while the genome project on Rhodococcus erythropolis SK121 [294] is still in process.…”

Section: The Genus Rhodococcusmentioning

confidence: 99%

Monooxygenases involved in the n-alkanes metabolism by Rhodococcus sp. BCP1: molecular characterization and expression of alkB gene

Cappelletti

Fedi

Honda

et al. 2010

Journal of Biotechnology

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Discussion 107 Summary 113Chapter 5 -Analysis of the alkB gene expression Summary 157Chapter 6 -Proteomic analysis of n-alkanes growth of Rhodococcus sp. BCP1 Chapter 1 -General Introduction PrefaceThe quality of life on Earth is tightly related with the overall quality of the environment [1]. During the last century it was commonly believed that the abundance of land and resources were unlimited and it was rarely acknowledged that the production, use, and disposal of hazardous substances had environmental and health effects [1][2][3]. Owing to this, human activity has deliberately or inadvertently released into waters and soil a variety of toxic compounds as refrigerants, paints, solvents, herbicides and pesticides that can cause considerable environmental pollution and human health problems as a result of their persistence, toxicity, and transformation into hazardous metabolites [4,5]. Very soon, however, it became clear how the carelessness and negligence in handling the industrial wastes and gas emissions had caused dramatic effect on the nature and on human health [1].Nowadays, the concern about the global warming and the climate changing induced the government regulatory agencies to establish procedures for assessing the environmental impact and health hazards of chemicals and for controlling/limiting their utilization.International efforts have been applied to remedy many contaminated sites all over the world, either as a response to the risk of adverse health or environmental effects caused by contamination or to enable the site to be redeveloped for use [5]. In response to public and government concern and because of the intriguing research problems presented, environmental scientists, biologists and chemists have been giving increased attention to identifying and determining the behavior and fate of organic compounds in natural ecosystems [5].Bioremediation procedures offer an economical and effective possibility to degrade or render innocuous toxic pollutants using natural biological activity [1]. By definition, bioremediation implies the use of living organisms, primarily microorganisms, to degrade the Since contaminant compounds are transformed by living organisms through reactions that take place as a part of their metabolic processes, environmental biotechnology focuses on the development of techniques to optimize environmental parameters to allow these metabolic pathways to proceed faster and, therefore, to improve the bio-degradation [1]. As a result, the removal of the contaminated soil can be necessary to let the biodegradation proceed in controlled sites (such as bioreactors). These ex situ approaches provide optimal conditions out one single step of the entire bio-degradation process. Hydrocarbons in the environmentHydrocarbons are energy-rich organic compounds consisting of carbon and hydrogen atoms and they can be saturated (only single C-H bounds) or unsaturated (one ore more double or triple C-H bounds). Alkanes are saturated hydrocarbons with the general formula C n H 2n+2 ; they can b...

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Biphenyl-inducible Promoters in a Polychlorinated Biphenyl-degrading Bacterium,Rhodococcussp. RHA1

Cited by 31 publications

References 17 publications

Roles of Ring-Hydroxylating Dioxygenases in Styrene and Benzene Catabolism inRhodococcus jostiiRHA1

Roles of Ring-Hydroxylating Dioxygenases in Styrene and Benzene Catabolism inRhodococcus jostiiRHA1

Dual Two-Component Regulatory Systems Are Involved in Aromatic Compound Degradation in a Polychlorinated-Biphenyl Degrader, Rhodococcus jostii RHA1

Monooxygenases involved in the n-alkanes metabolism by Rhodococcus sp. BCP1: molecular characterization and expression of alkB gene

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