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Suzuki-Minakuchi C, Yamamoto N, Takahira S, Yamaguchi M, Takeda Y, Okada K, Shigeto S, Nojiri H. Transcriptional heterogeneity of catabolic genes on the plasmid pCAR1 causes host-specific carbazole degradation. Appl Environ Microbiol 2024; 90:e0124723. [PMID: 38289097 PMCID: PMC10880608 DOI: 10.1128/aem.01247-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Accepted: 12/21/2023] [Indexed: 02/22/2024] Open
Abstract
To elucidate why plasmid-borne catabolic ability differs among host bacteria, we assessed the expression dynamics of the Pant promoter on the carbazole-degradative conjugative plasmid pCAR1 in Pseudomonas putida KT2440(pCAR1) (hereafter, KTPC) and Pseudomonas resinovorans CA10. The Pant promoter regulates the transcription of both the car and ant operons, which are responsible for converting carbazole into anthranilate and anthranilate into catechol, respectively. In the presence of anthranilate, transcription of the Pant promoter is induced by the AraC/XylS family regulator AntR, encoded on pCAR1. A reporter cassette containing the Pant promoter followed by gfp was inserted into the chromosomes of KTPC and CA10. After adding anthranilate, GFP expression in the population of CA10 showed an unimodal distribution, whereas a small population with low GFP fluorescence intensity appeared for KTPC. CA10 has a gene, antRCA, that encodes an iso-functional homolog of AntR on its chromosome. When antRCA was disrupted, a small population with low GFP fluorescence intensity appeared. In contrast, overexpression of pCAR1-encoded AntR in KTPC resulted in unimodal expression under the Pant promoter. These results suggest that the expression of pCAR1-encoded AntR is insufficient to ameliorate the stochastic expression of the Pant promoter. Raman spectra of single cells collected using deuterium-labeled carbazole showed that the C-D Raman signal exhibited greater variability for KTPC than CA10. These results indicate that heterogeneity at the transcriptional level of the Pant promoter due to insufficient AntR availability causes fluctuations in the pCAR1-borne carbazole-degrading capacity of host bacterial cells.IMPORTANCEHorizontally acquired genes increase the competitiveness of host bacteria under selective conditions, although unregulated expression of foreign genes may impose fitness costs. The "appropriate" host for a plasmid is empirically known to maximize the expression of plasmid-borne traits. In the case of pCAR1-harboring Pseudomonas strains, P. resinovorans CA10 exhibits strong carbazole-degrading capacity, whereas P. putida KT2440 harboring pCAR1 exhibits low degradation capacity. Our results suggest that a chromosomally encoded transcription factor affects transcriptional and metabolic fluctuations in host cells, resulting in different carbazole-degrading capacities as a population. This study may provide a clue for determining appropriate hosts for a plasmid and for regulating the expression of plasmid-borne traits, such as the degradation of xenobiotics and antibiotic resistance.
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Affiliation(s)
- Chiho Suzuki-Minakuchi
- Agro-Biotechnology Research Center, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo, Japan
| | - Natsumi Yamamoto
- Agro-Biotechnology Research Center, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Saki Takahira
- Agro-Biotechnology Research Center, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Masataka Yamaguchi
- Department of Chemistry, Graduate School of Science and Technology, Kwansei Gakuin University, Hyogo, Japan
| | - Yutaro Takeda
- Agro-Biotechnology Research Center, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Kazunori Okada
- Agro-Biotechnology Research Center, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Shinsuke Shigeto
- Department of Chemistry, Graduate School of Science and Technology, Kwansei Gakuin University, Hyogo, Japan
| | - Hideaki Nojiri
- Agro-Biotechnology Research Center, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo, Japan
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Vasileiadis S, Perruchon C, Scheer B, Adrian L, Steinbach N, Trevisan M, Plaza-Bolaños P, Agüera A, Chatzinotas A, Karpouzas DG. Nutritional inter-dependencies and a carbazole-dioxygenase are key elements of a bacterial consortium relying on a Sphingomonas for the degradation of the fungicide thiabendazole. Environ Microbiol 2022; 24:5105-5122. [PMID: 35799498 DOI: 10.1111/1462-2920.16116] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 06/20/2022] [Accepted: 06/21/2022] [Indexed: 11/28/2022]
Abstract
Thiabendazole (TBZ), is a persistent fungicide/anthelminthic and a serious environmental threat. We previously enriched a TBZ-degrading bacterial consortium and provided first evidence for a Sphingomonas involvement in TBZ transformation. Here, using a multi-omic approach combined with DNA-stable isotope probing (SIP) we verified the key degrading role of Sphingomonas and identify potential microbial interactions governing consortium functioning. SIP and amplicon sequencing analysis of the heavy and light DNA fraction of cultures grown on 13 C-labelled versus 12 C-TBZ showed that 66% of the 13 C-labelled TBZ was assimilated by Sphingomonas. Metagenomic analysis retrieved 18 metagenome-assembled genomes with the dominant belonging to Sphingomonas, Sinobacteriaceae, Bradyrhizobium, Filimonas and Hydrogenophaga. Meta-transcriptomics/-proteomics and non-target mass spectrometry suggested TBZ transformation by Sphingomonas via initial cleavage by a carbazole dioxygenase (car) to thiazole-4-carboxamidine (terminal compound) and catechol or a cleaved benzyl ring derivative, further transformed through an ortho-cleavage (cat) pathway. Microbial co-occurrence and gene expression networks suggested strong interactions between Sphingomonas and a Hydrogenophaga. The latter activated its cobalamin biosynthetic pathway and Sphingomonas its cobalamin salvage pathway to satisfy its B12 auxotrophy. Our findings indicate microbial interactions aligning with the 'black queen hypothesis' where Sphingomonas (detoxifier, B12 recipient) and Hydrogenophaga (B12 producer, enjoying detoxification) act as both helpers and beneficiaries.
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Affiliation(s)
- Sotirios Vasileiadis
- Laboratory of Plant and Environmental Biotechnology, Department of Biochemistry and Biotechnology, University of Thessaly, Larissa, Viopolis, Greece
| | - Chiara Perruchon
- Laboratory of Plant and Environmental Biotechnology, Department of Biochemistry and Biotechnology, University of Thessaly, Larissa, Viopolis, Greece
| | - Benjamin Scheer
- Department of Environmental Biotechnology, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany
| | - Lorenz Adrian
- Department of Environmental Biotechnology, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany.,Chair of Geobiotechnology, Technische Universität Berlin, Berlin, Germany
| | - Nicole Steinbach
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany
| | - Marco Trevisan
- Department of Sustainable Food Process, Universitá Cattolica del Sacro Cuore, Piacenza, Italy
| | - Patricia Plaza-Bolaños
- Solar Energy Research Centre (CIESOL), Joint Center University of Almería-CIEMAT, Almeria, Spain
| | - Ana Agüera
- Solar Energy Research Centre (CIESOL), Joint Center University of Almería-CIEMAT, Almeria, Spain
| | - Antonis Chatzinotas
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany.,Institute of Biology, Leipzig University, Leipzig, Germany.,German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
| | - Dimitrios G Karpouzas
- Laboratory of Plant and Environmental Biotechnology, Department of Biochemistry and Biotechnology, University of Thessaly, Larissa, Viopolis, Greece
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Phale PS, Malhotra H, Shah BA. Degradation strategies and associated regulatory mechanisms/features for aromatic compound metabolism in bacteria. ADVANCES IN APPLIED MICROBIOLOGY 2020; 112:1-65. [PMID: 32762865 DOI: 10.1016/bs.aambs.2020.02.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
As a result of anthropogenic activity, large number of recalcitrant aromatic compounds have been released into the environment. Consequently, microbial communities have adapted and evolved to utilize these compounds as sole carbon source, under both aerobic and anaerobic conditions. The constitutive expression of enzymes necessary for metabolism imposes a heavy energy load on the microbe which is overcome by arrangement of degradative genes as operons which are induced by specific inducers. The segmentation of pathways into upper, middle and/or lower operons has allowed microbes to funnel multiple compounds into common key aromatic intermediates which are further metabolized through central carbon pathway. Various proteins belonging to diverse families have evolved to regulate the transcription of individual operons participating in aromatic catabolism. These proteins, complemented with global regulatory mechanisms, carry out the regulation of aromatic compound metabolic pathways in a concerted manner. Additionally, characteristics like chemotaxis, preferential utilization, pathway compartmentalization and biosurfactant production confer an advantage to the microbe, thus making bioremediation of the aromatic pollutants more efficient and effective.
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Affiliation(s)
- Prashant S Phale
- Department of Biosciences and Bioengineering, Indian Institute of Technology-Bombay, Mumbai, India.
| | - Harshit Malhotra
- Department of Biosciences and Bioengineering, Indian Institute of Technology-Bombay, Mumbai, India
| | - Bhavik A Shah
- Department of Biosciences and Bioengineering, Indian Institute of Technology-Bombay, Mumbai, India
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The PaaX-type repressor MeqR2 of Arthrobacter sp. strain Rue61a, involved in the regulation of quinaldine catabolism, binds to its own promoter and to catabolic promoters and specifically responds to anthraniloyl coenzyme A. J Bacteriol 2012; 195:1068-80. [PMID: 23275246 DOI: 10.1128/jb.01547-12] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The genes coding for quinaldine catabolism in Arthrobacter sp. strain Rue61a are clustered on the linear plasmid pAL1 in two upper pathway operons (meqABC and meqDEF) coding for quinaldine conversion to anthranilate and a lower pathway operon encoding anthranilate degradation via coenzyme A (CoA) thioester intermediates. The meqR2 gene, located immediately downstream of the catabolic genes, codes for a PaaX-type transcriptional repressor. MeqR2, purified as recombinant fusion protein, forms a dimer in solution and shows specific and cooperative binding to promoter DNA in vitro. DNA fragments recognized by MeqR2 contained a highly conserved palindromic motif, 5'-TGACGNNCGTcA-3', which is located at positions -35 to -24 of the two promoters that control the upper pathway operons, at positions +4 to +15 of the promoter of the lower pathway genes and at positions +53 to +64 of the meqR2 promoter. Disruption of the palindrome abolished MeqR2 binding. The dissociation constants (K(D)) of MeqR2-DNA complexes as deduced from electrophoretic mobility shift assays were very similar for the four promoters tested (23 nM to 28 nM). Anthraniloyl-CoA was identified as the specific effector of MeqR2, which impairs MeqR2-DNA complex formation in vitro. A binding stoichiometry of one effector molecule per MeqR2 monomer and a K(D) of 22 nM were determined for the effector-protein complex by isothermal titration calorimetry (ITC). Quantitative reverse transcriptase PCR analyses suggested that MeqR2 is a potent regulator of the meqDEF operon; however, additional regulatory systems have a major impact on transcriptional control of the catabolic operons and of meqR2.
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Structural and molecular genetic analyses of the bacterial carbazole degradation system. Biosci Biotechnol Biochem 2012; 76:1-18. [PMID: 22232235 DOI: 10.1271/bbb.110620] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Carbazole degradation by several bacterial strains, including Pseudomonas resinovorans CA10, has been investigated over the last two decades. As the initial reaction in degradation pathways, carbazole is commonly oxygenated at angular (C9a) and adjacent (C1) carbons as two hydroxyl groups in a cis configuration. This type of dioxygenation is termed "angular dioxygenation," and is catalyzed by carbazole 1,9a-dioxygenase (CARDO), consisting of terminal oxygenase, ferredoxin, and ferredoxin reductase components. The crystal structures of all components and the electron transfer complex between terminal oxygenase and ferredoxin indicate substrate recognition mechanisms suitable for angular dioxygenation and specific electron transfer among the three components. In contrast, the carbazole degradative car operon of CA10 is located on IncP-7 conjugative plasmid pCAR1. Together with conventional molecular genetic and biochemical investigations, recent genome sequencing and RNA mapping studies have clarified that transcriptional cross-regulation via nucleoid-associated proteins is established between pCAR1 and the host chromosome.
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Shintani M, Takahashi Y, Yamane H, Nojiri H. The behavior and significance of degradative plasmids belonging to Inc groups in Pseudomonas within natural environments and microcosms. Microbes Environ 2011; 25:253-65. [PMID: 21576880 DOI: 10.1264/jsme2.me10155] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Over the past few decades, degradative plasmids have been isolated from bacteria capable of degrading a variety of both natural and man-made compounds. Degradative plasmids belonging to three incompatibility (Inc) groups in Pseudomonas (IncP-1, P-7, and P-9) have been well studied in terms of their replication, maintenance, and capacity for conjugative transfer. The host ranges of these plasmids are determined by replication or conjugative transfer systems. The host range of IncP-1 is broad, that of IncP-9 is intermediate, and that of IncP-7 is narrow. To understand the behavior of these plasmids and their hosts in various environments, the survivability of inocula, stability or transferability, and efficiency of biodegradation in environments and microcosms have been monitored. The biodegradation and plasmid transfer in various environments have been observed for all three groups, although the kinds of transconjugants differed with the Inc groups. In some cases, the deletion and amplification of catabolic genes acted to reduce the production of toxic catabolic intermediates, or to increase the activity on a particular catabolic pathway. The combination of degradative genes, the plasmid backbone of each Inc group, and the host of the plasmids is key to the degraders adapting to various hosts or to heterogeneous environments.
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Affiliation(s)
- Masaki Shintani
- Bioresource Center, Japan Collection of Microorganisms (BRC-JCM), Riken, 2–1 Hirosawa, Wako, Saitama 351–0198, Japan
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Shintani M, Horisaki T, Yamane H, Ohkuma M, Nojiri H. Evolution of the IncP-7 carbazole-degradative plasmid pCAR1 improves survival of its host Pseudomonas fluorescens Pf0-1 in artificial water microcosms. Microbiology (Reading) 2011; 157:2276-2286. [DOI: 10.1099/mic.0.049064-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In our previous study, Pseudomonas fluorescens Pf0-1L, harbouring the IncP-7 carbazole-degradative plasmid pCAR1 : : rfp, was shown to be undetectable within 5 days post-inoculation in carbazole-contaminated artificial freshwater microcosms containing several plasmid-free bacteria in addition to Pf0-1L(pCAR1 : : rfp). Fourteen days after the inoculation, carbazole degraders become detectable. Here, we revealed that these isolates were not pCAR1 transconjugants, but Pf0-1L(pCAR1 : : rfp) mutants, based on RFLP and BOX-A1R-based repetitive extragenic palindromic-PCR (BOX-PCR) analysis. Notably, the mutants displayed more rapid initiation of carbazole degradation than the parent strain Pf0-1L(pCAR1 : : rfp). The mutants were unable to degrade anthranilate due to a 163 bp deletion in the antA gene, which was overcome by their transformation with a wild-type antABC-expressing plasmid. Quantitative RT-PCR analysis indicated that the transcriptional induction of carbazole-, anthranilate- and catechol-degradative genes was comparable in both parent and mutant strains. The deletion mutants became dominant in the artificial water microcosm. The mutation caused anthranilate to accumulate instead of catechol, a toxic compound for the parent strain, and may be beneficial to host survival in artificial microcosms.
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Affiliation(s)
- Masaki Shintani
- Japan Collection of Microorganisms, BioResource Center, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Tadafumi Horisaki
- Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Hisakazu Yamane
- Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Moriya Ohkuma
- Japan Collection of Microorganisms, BioResource Center, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Hideaki Nojiri
- Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
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Shintani M, Tokumaru H, Takahashi Y, Miyakoshi M, Yamane H, Nishida H, Nojiri H. Alterations of RNA maps of IncP-7 plasmid pCAR1 in various Pseudomonas bacteria. Plasmid 2011; 66:85-92. [PMID: 21708189 DOI: 10.1016/j.plasmid.2011.06.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2011] [Revised: 06/07/2011] [Accepted: 06/08/2011] [Indexed: 10/18/2022]
Abstract
RNA transcripts from 199-kb incompatibility P-7 plasmid pCAR1 were analyzed using microarrays with evenly tiled probes with a nine-nucleotide offset in six different Pseudomonas host strains. We re-annotated 12 ORFs based on their RNA maps and on the comparisons with other sequenced IncP-7 plasmids. Ninety six of two hundred ORFs were identified on the IncP-7 backbone related to basic functions of the plasmid (replication, partition and conjugative transfer). More than 90% ORFs on the backbone were transcribed in each host strain, suggesting their importance for the plasmid survival in the host strains. Genes related to partition and conjugative transfer were differentially transcribed host by host, whereas the repA gene encoding replication initiation protein was transcribed at comparable level in each host. As for other plasmid 'accessory genes' of pCAR1 encoding carbazole degradation, putative transporter, or transposase were also differentially transcribed among different host strains. These differences may have resulted in distinct behaviors of the plasmid or of its host strain, and RNA maps of pCAR1 give us important information to understand the plasmid behaviors in different environments.
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Affiliation(s)
- Masaki Shintani
- Biotechnology Research Center, The University of Tokyo, Tokyo, Japan
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Shintani M, Takahashi Y, Tokumaru H, Kadota K, Hara H, Miyakoshi M, Naito K, Yamane H, Nishida H, Nojiri H. Response of thePseudomonashost chromosomal transcriptome to carriage of the IncP-7 plasmid pCAR1. Environ Microbiol 2009; 12:1413-26. [DOI: 10.1111/j.1462-2920.2009.02110.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Takahashi Y, Shintani M, Li L, Yamane H, Nojiri H. Carbazole-degradative IncP-7 plasmid pCAR1.2 is structurally unstable in Pseudomonas fluorescens Pf0-1, which accumulates catechol, the intermediate of the carbazole degradation pathway. Appl Environ Microbiol 2009; 75:3920-9. [PMID: 19376894 PMCID: PMC2698365 DOI: 10.1128/aem.02373-08] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2008] [Accepted: 04/09/2009] [Indexed: 11/20/2022] Open
Abstract
We determined the effect of the host on the function and structure of the nearly identical IncP-7 carbazole-degradative plasmids pCAR1.1 and pCAR1.2. We constructed Pseudomonas aeruginosa PAO1(pCAR1.2) and P. fluorescens Pf0-1Km(pCAR1.2) and compared their growth on carbazole- and succinate-containing media with that of P. putida KT2440(pCAR1.1). We also assessed the stability of the genetic structures of the plasmids in each of the three hosts. Pf0-1Km(pCAR1.2) showed dramatically delayed growth when carbazole was supplied as the sole carbon source, while the three strains grew at nearly the same rate on succinate. Among the carbazole-grown Pf0-1Km(pCAR1.2) cells, two types of deficient strains appeared and dominated the population; such dominance was not observed in the other two strains or for succinate-grown Pf0-1Km(pCAR1.2). Genetic analysis showed that the two deficient strains possessed pCAR1.2 derivatives in which the carbazole-degradative car operon was deleted or its regulatory gene, antR, was deleted by homologous recombination between insertion sequences. From genomic information and quantitative reverse transcription-PCR analyses of the genes involved in carbazole mineralization by Pf0-1Km(pCAR1.2), we found that the cat genes on the chromosome of Pf0-1Km, which are necessary for the degradation of catechol (a toxic intermediate in the carbazole catabolic pathway), were not induced in the presence of carbazole. The resulting accumulation of catechol may have enabled the strain that lost its carbazole-degrading ability to have overall higher fitness than the wild-type strain. These results suggest that the functions of the chromosomal genes contributed to the selection of plasmid derivatives with altered structures.
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Affiliation(s)
- Yurika Takahashi
- Biotechnology Research Center, The University of Tokyo, Yayoi, Bunkyo-ku, Japan
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Pathway and evolutionary implications of diphenylamine biodegradation by Burkholderia sp. strain JS667. Appl Environ Microbiol 2009; 75:2694-704. [PMID: 19251893 DOI: 10.1128/aem.02198-08] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Diphenylamine (DPA) is a common contaminant at munitions-contaminated sites as well as at aniline manufacturing sites. Little is known about the biodegradation of the compound, and bacteria able to use DPA as the growth substrate have not been reported. Burkholderia sp. strain JS667 and Ralstonia sp. strain JS668 were isolated by selective enrichment from DPA-contaminated sediment. The isolates grew aerobically with DPA as the sole carbon, nitrogen, and energy source. During induction of DPA degradation, stoichiometric amounts of aniline accumulated and then disappeared, which suggested that aniline is on the DPA degradation pathway. Genes encoding the enzymes that catalyze the initial steps in DPA degradation were cloned from the genomic DNA of strain JS667. The Escherichia coli clone catalyzed stoichiometric transformation of DPA to aniline and catechol. Transposon mutagenesis, the sequence similarity of putative open reading frames to those of well-characterized dioxygenases, and (18)O(2) experiments support the conclusion that the initial reaction in DPA degradation is catalyzed by a multicomponent ring-hydroxylating dioxygenase. DPA is converted to aniline and catechol via dioxygenation at the 1,2 position of the aromatic ring and spontaneous rearomatization. Aniline and catechol are further biodegraded by the well-established aniline degradation pathway. Genes that encode the complete aniline degradation pathway were found 12 kb downstream of the genes that encode the initial dioxygenase. Expression of the relevant dioxygenases was confirmed by reverse transcription-PCR analysis. Both the sequence similarity and the gene organization suggest that the DPA degradation pathway evolved recently by the recruitment of two gene clusters that encode the DPA dioxygenase and aniline degradation pathway.
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Miyakoshi M, Nishida H, Shintani M, Yamane H, Nojiri H. High-resolution mapping of plasmid transcriptomes in different host bacteria. BMC Genomics 2009; 10:12. [PMID: 19134166 PMCID: PMC2642839 DOI: 10.1186/1471-2164-10-12] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2008] [Accepted: 01/09/2009] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Plasmids are extrachromosomal elements that replicate autonomously, and many can be transmitted between bacterial cells through conjugation. Although the transcription pattern of genes on a plasmid can be altered by a change in host background, the expression range of plasmid genes that will result in phenotypic variation has not been quantitatively investigated. RESULTS Using a microarray with evenly tiled probes at a density of 9 bp, we mapped and quantified the transcripts of the carbazole catabolic plasmid pCAR1 in its original host Pseudomonas resinovorans CA10 and the transconjugant P. putida KT2440(pCAR1) during growth on either carbazole or succinate as the sole carbon source. We identified the operons in pCAR1, which consisted of nearly identical transcription units despite the difference in host background during growth on the same carbon source. In accordance with previous studies, the catabolic operons for carbazole degradation were upregulated during growth on carbazole in both hosts. However, our tiling array results also showed that several operons flanking the transfer gene cluster were transcribed at significantly higher levels in the transconjugant than in the original host. The number of transcripts and the positions of the transcription start sites agreed with our quantitative RT-PCR and primer extension results. CONCLUSION Our tiling array results indicate that the levels of transcription for the operons on a plasmid can vary by host background. High-resolution mapping using an unbiased tiling array is a valuable tool for the simultaneous identification and quantification of prokaryotic transcriptomes including polycistronic operons and non-coding RNAs.
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The GAF-like-domain-containing transcriptional regulator DfdR is a sensor protein for dibenzofuran and several hydrophobic aromatic compounds. J Bacteriol 2008; 191:123-34. [PMID: 18952799 DOI: 10.1128/jb.01112-08] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Dibenzofuran (DF) is one of the dioxin carbon skeletal compounds used as a model to study the microbial degradation of dioxins. This study analyzed the transcriptional regulation of the DF dioxygenase genes dfdA1 to dfdA4 in the DF-utilizing actinomycetes Rhodococcus sp. strain YK2 and Terrabacter sp. strain YK3. An open reading frame designated dfdR was detected downstream of the dfdC genes. The C-terminal part of the DfdR amino acid sequence has high levels of similarity to several LuxR-type DNA binding helix-turn-helix domains, and a GAF domain sequence in the central part was detected by a domain search analysis. A derivative of YK2 with dfdR disrupted was not able to utilize DF and did not exhibit DF-dependent dfdA1 transcriptional induction ability, and these dysfunctions were compensated for by introduction of dfdR. Promoter analysis of dfdA1 in Rhodococcus strains indicated that activation of the dfdA1 promoter (P(dfdA1)) was dependent on dfdR and DF and not on a metabolite of the DF pathway. The cell extract of a Rhodococcus strain that heterologously expressed DfdR showed electrophoretic mobility shift (EMS) activity for the P(dfdA1) DNA fragment in a DF-dependent manner. In addition, P(dfdA1) activation and EMS activity were observed with hydrophobic aromatic compounds comprising two or more aromatic rings, suggesting that DfdR has broad effector molecule specificity for several hydrophobic aromatic compounds.
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Miyakoshi M, Shintani M, Terabayashi T, Kai S, Yamane H, Nojiri H. Transcriptome analysis of Pseudomonas putida KT2440 harboring the completely sequenced IncP-7 plasmid pCAR1. J Bacteriol 2007; 189:6849-60. [PMID: 17675379 PMCID: PMC2045235 DOI: 10.1128/jb.00684-07] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2007] [Accepted: 07/19/2007] [Indexed: 11/20/2022] Open
Abstract
The IncP-7 plasmid pCAR1 of Pseudomonas resinovorans CA10 confers the ability to degrade carbazole upon transfer to the recipient strain P. putida KT2440. We designed a customized whole-genome oligonucleotide microarray to study the coordinated expression of pCAR1 and the chromosome in the transconjugant strain KT2440(pCAR1). First, the transcriptome of KT2440(pCAR1) during growth with carbazole as the sole carbon source was compared to that during growth with succinate. The carbazole catabolic car and ant operons were induced, along with the chromosomal cat and pca genes involved in the catechol branch of the beta-ketoadipate pathway. Additionally, the regulatory gene antR encoding the AraC/XylS family transcriptional activator specific for car and ant operons was upregulated. The characterization of the antR promoter revealed that antR is transcribed from an RpoN-dependent promoter, suggesting that the successful expression of the carbazole catabolic operons depends on whether the chromosome contains the specific RpoN-dependent activator. Next, to analyze whether the horizontal transfer of a plasmid alters the transcription network of its host chromosome, we compared the chromosomal transcriptomes of KT2440(pCAR1) and KT2440 under the same growth conditions. Only subtle changes were caused by the transfer of pCAR1, except for the significant induction of the hypothetical gene PP3700, designated parI, which encodes a putative ParA-like ATPase with an N-terminal Xre-type DNA-binding motif. Further transcriptional analyses showed that the parI promoter was positively regulated by ParI itself and the pCAR1-encoded protein ParA.
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Affiliation(s)
- Masatoshi Miyakoshi
- Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
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Inoue K, Habe H, Yamane H, Nojiri H. Characterization of novel carbazole catabolism genes from gram-positive carbazole degrader Nocardioides aromaticivorans IC177. Appl Environ Microbiol 2006; 72:3321-9. [PMID: 16672473 PMCID: PMC1472339 DOI: 10.1128/aem.72.5.3321-3329.2006] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2005] [Accepted: 02/28/2006] [Indexed: 11/20/2022] Open
Abstract
Nocardioides aromaticivorans IC177 is a gram-positive carbazole degrader. The genes encoding carbazole degradation (car genes) were cloned into a cosmid clone and sequenced partially to reveal 19 open reading frames. The car genes were clustered into the carAaCBaBbAcAd and carDFE gene clusters, encoding the enzymes responsible for the degradation of carbazole to anthranilate and 2-hydroxypenta-2,4-dienoate and of 2-hydroxypenta-2,4-dienoate to pyruvic acid and acetyl coenzyme A, respectively. The conserved amino acid motifs proposed to bind the Rieske-type [2Fe-2S] cluster and mononuclear iron, the Rieske-type [2Fe-2S] cluster, and flavin adenine dinucleotide were found in the deduced amino acid sequences of carAa, carAc, and carAd, respectively, which showed similarities with CarAa from Sphingomonas sp. strain KA1 (49% identity), CarAc from Pseudomonas resinovorans CA10 (31% identity), and AhdA4 from Sphingomonas sp. strain P2 (37% identity), respectively. Escherichia coli cells expressing CarAaAcAd exhibited major carbazole 1,9a-dioxygenase (CARDO) activity. These data showed that the IC177 CARDO is classified into class IIB, while gram-negative CARDOs are classified into class III or IIA, indicating that the respective CARDOs have diverse types of electron transfer components and high similarities of the terminal oxygenase. Reverse transcription-PCR (RT-PCR) experiments showed that the carAaCBaBbAcAd and carDFE gene clusters are operonic. The results of quantitative RT-PCR experiments indicated that transcription of both operons is induced by carbazole or its metabolite, whereas anthranilate is not an inducer. Biotransformation analysis showed that the IC177 CARDO exhibits significant activities for naphthalene, carbazole, and dibenzo-p-dioxin but less activity for dibenzofuran and biphenyl.
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Affiliation(s)
- Kengo Inoue
- Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
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