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Arthrobacter aurescens TC1 atrazine catabolism genes trzN, atzB, and atzC are linked on a 160-kilobase region and are functional in Escherichia coli.

ABSTRACT: Arthrobacter aurescens strain TC1 metabolizes atrazine to cyanuric acid via TrzN, AtzB, and AtzC. The complete sequence of a 160-kb bacterial artificial chromosome clone indicated that trzN, atzB, and atzC are linked on the A. aurescens genome. TrzN, AtzB, and AtzC were shown to be functional in Escherichia coli. Hybridization studies localized trzN, atzB, and atzC to a 380-kb plasmid in A. aurescens strain TC1.

SUBMITTER: Sajjaphan K

PROVIDER: S-EPMC444770 | biostudies-literature | 2004 Jul

REPOSITORIES: biostudies-literature

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Arthrobacter aurescens TC1 atrazine catabolism genes trzN, atzB, and atzC are linked on a 160-kilobase region and are functional in Escherichia coli.

Sajjaphan Kannika K Shapir Nir N Wackett Lawrence P LP Palmer Michael M Blackmon Barbara B Tomkins Jeff J Sadowsky Michael J MJ

Applied and environmental microbiology 20040701 7

Arthrobacter aurescens strain TC1 metabolizes atrazine to cyanuric acid via TrzN, AtzB, and AtzC. The complete sequence of a 160-kb bacterial artificial chromosome clone indicated that trzN, atzB, and atzC are linked on the A. aurescens genome. TrzN, AtzB, and AtzC were shown to be functional in Escherichia coli. Hybridization studies localized trzN, atzB, and atzC to a 380-kb plasmid in A. aurescens strain TC1. ...[more]

PMID: 15240330

Similar Datasets

TrzN from Arthrobacter aurescens TC1 Is a zinc amidohydrolase.

Project description:TrzN, the broad-specificity triazine hydrolase from Arthrobacter and Nocardioides spp., is reportedly in the amidohydrolase superfamily of metalloenzymes, but previous studies suggested that a metal was not required for activity. To help resolve that conundrum, a double chaperone expression system was used to produce multimilligram quantities of functionally folded, recombinant TrzN. The TrzN obtained from Escherichia coli (trzN) cells cultured with increasing zinc in the growth medium showed corresponding increases in specific activity, and enzyme obtained from cells grown with 500 muM zinc showed maximum activity. Recombinant TrzN contained 1 mole of Zn per mole of TrzN subunit. Maximally active TrzN was not affected by supplementation with most metals nor by EDTA, consistent with previous observations (E. Topp, W. M. Mulbry, H. Zhu, S. M. Nour, and D. Cuppels, Appl. Environ. Microbiol. 66:3134-3141, 2000) which had led to the conclusion that TrzN is not a metalloenzyme. Fully active native TrzN showed a loss of greater than 90% of enzyme activity and bound zinc when treated with the metal chelator 8-hydroxyquinoline-5-sulfonic acid. While exogenously added zinc or cobalt restored activity to metal-depleted TrzN, cobalt supported lower activity than did zinc. Iron, manganese, nickel, and copper did not support TrzN activity. Both Zn- and Co-TrzN showed different relative activities with different s-triazine substrates. Co-TrzN showed a visible absorption spectrum characteristic of other members of the amidohydrolase superfamily replaced with cobalt.

| S-EPMC1540083 | biostudies-literature

Substrate specificity and colorimetric assay for recombinant TrzN derived from Arthrobacter aurescens TC1.

Project description:The TrzN protein, which is involved in s-triazine herbicide catabolism by Arthrobacter aurescens TC1, was cloned and expressed in Escherichia coli as a His-tagged protein. The recombinant protein was purified via nickel column chromatography. The purified TrzN protein was tested with 31 s-triazine and pyrimidine ring compounds; 22 of the tested compounds were substrates. TrzN showed high activity with sulfur-substituted s-triazines and the highest activity with ametryn sulfoxide. Hydrolysis of ametryn sulfoxide by TrzN, both in vitro and in vivo, yielded a product(s) that reacted with 7-chloro-4-nitrobenz-2-oxa-1,3-diazole (NBD-Cl) to generate a diagnostic blue product. Atrazine chlorohydrolase, AtzA, did not hydrolyze ametryn sulfoxide, and no color was formed by amending those enzyme incubations with NBD-Cl. TrzN and AtzA could also be distinguished by reaction with ametryn. TrzN, but not AtzA, hydrolyzed ametryn to methylmercaptan. Methylmercaptan reacted with NBD-Cl to produce a diagnostic yellow product having an absorption maximum at 420 nm. The yellow color with ametryn was shown to selectively demonstrate the presence of TrzN, but not AtzA or other enzymes, in whole microbial cells. The present study was the first to purify an active TrzN protein in recombinant form and develop a colorimetric test for determining TrzN activity, and it significantly extends the known substrate range for TrzN.

| S-EPMC1087567 | biostudies-literature

Defining lower limits of biodegradation: atrazine degradation regulated by mass transfer and maintenance demand in Arthrobacter aurescens TC1.

Project description:Exploring adaptive strategies by which microorganisms function and survive in low-energy natural environments remains a grand goal of microbiology, and may help address a prime challenge of the 21st century: degradation of man-made chemicals at low concentrations ("micropollutants"). Here we explore physiological adaptation and maintenance energy requirements of a herbicide (atrazine)-degrading microorganism (Arthrobacter aurescens TC1) while concomitantly observing mass transfer limitations directly by compound-specific isotope fractionation analysis. Chemostat-based growth triggered the onset of mass transfer limitation at residual concentrations of 30 μg L-1 of atrazine with a bacterial population doubling time (td) of 14 days, whereas exacerbated energy limitation was induced by retentostat-based near-zero growth (td = 265 days) at 12 ± 3 μg L-1 residual concentration. Retentostat cultivation resulted in (i) complete mass transfer limitation evidenced by the disappearance of isotope fractionation (ε13C = -0.45‰ ± 0.36‰) and (ii) a twofold decrease in maintenance energy requirement compared with chemostat cultivation. Proteomics revealed that retentostat and chemostat cultivation under mass transfer limitation share low protein turnover and expression of stress-related proteins. Mass transfer limitation effectuated slow-down of metabolism in retentostats and a transition from growth phase to maintenance phase indicating a limit of ≈10 μg L-1 for long-term atrazine degradation. Further studies on other ecosystem-relevant microorganisms will substantiate the general applicability of our finding that mass transfer limitation serves as a trigger for physiological adaptation, which subsequently defines a lower limit of biodegradation.

| S-EPMC6776027 | biostudies-literature

Arthrobacter aurescens TC1 metabolizes diverse s-triazine ring compounds.

Project description:Arthrobacter aurescens strain TC1 was isolated without enrichment by plating atrazine-contaminated soil directly onto atrazine-clearing plates. A. aurescens TC1 grew in liquid medium with atrazine as the sole source of nitrogen, carbon, and energy, consuming up to 3,000 mg of atrazine per liter. A. aurescens TC1 is metabolically diverse and grew on a wider range of s-triazine compounds than any bacterium previously characterized. The 23 s-triazine substrates serving as the sole nitrogen source included the herbicides ametryn, atratone, cyanazine, prometryn, and simazine. Moreover, atrazine substrate analogs containing fluorine, mercaptan, and cyano groups in place of the chlorine substituent were also growth substrates. Analogs containing hydrogen, azido, and amino functionalities in place of chlorine were not growth substrates. A. aurescens TC1 also metabolized compounds containing chlorine plus N-ethyl, N-propyl, N-butyl, N-s-butyl, N-isobutyl, or N-t-butyl substituents on the s-triazine ring. Atrazine was metabolized to alkylamines and cyanuric acid, the latter accumulating stoichiometrically. Ethylamine and isopropylamine each served as the source of carbon and nitrogen for growth. PCR experiments identified genes with high sequence identity to atzB and atzC, but not to atzA, from Pseudomonas sp. strain ADP.

| S-EPMC134431 | biostudies-literature

Secrets of soil survival revealed by the genome sequence of Arthrobacter aurescens TC1.

Project description:Arthrobacter sp. strains are among the most frequently isolated, indigenous, aerobic bacterial genera found in soils. Member of the genus are metabolically and ecologically diverse and have the ability to survive in environmentally harsh conditions for extended periods of time. The genome of Arthrobacter aurescens strain TC1, which was originally isolated from soil at an atrazine spill site, is composed of a single 4,597,686 basepair (bp) circular chromosome and two circular plasmids, pTC1 and pTC2, which are 408,237 bp and 300,725 bp, respectively. Over 66% of the 4,702 open reading frames (ORFs) present in the TC1 genome could be assigned a putative function, and 13.2% (623 genes) appear to be unique to this bacterium, suggesting niche specialization. The genome of TC1 is most similar to that of Tropheryma, Leifsonia, Streptomyces, and Corynebacterium glutamicum, and analyses suggest that A. aurescens TC1 has expanded its metabolic abilities by relying on the duplication of catabolic genes and by funneling metabolic intermediates generated by plasmid-borne genes to chromosomally encoded pathways. The data presented here suggest that Arthrobacter's environmental prevalence may be due to its ability to survive under stressful conditions induced by starvation, ionizing radiation, oxygen radicals, and toxic chemicals.

| S-EPMC1713258 | biostudies-literature

Genome-scale reconstruction of Paenarthrobacter aurescens TC1 metabolic model towards the study of atrazine bioremediation.

Project description:Atrazine is an herbicide and a pollutant of great environmental concern that is naturally biodegraded by microbial communities. Paenarthrobacter aurescens TC1 is one of the most studied degraders of this herbicide. Here, we developed a genome scale metabolic model for P. aurescens TC1, iRZ1179, to study the atrazine degradation process at organism level. Constraint based flux balance analysis and time dependent simulations were used to explore the organism's phenotypic landscape. Simulations aimed at designing media optimized for supporting growth and enhancing degradation, by passing the need in strain design via genetic modifications. Growth and degradation simulations were carried with more than 100 compounds consumed by P. aurescens TC1. In vitro validation confirmed the predicted classification of different compounds as efficient, moderate or poor stimulators of growth. Simulations successfully captured previous reports on the use of glucose and phosphate as bio-stimulators of atrazine degradation, supported by in vitro validation. Model predictions can go beyond supplementing the medium with a single compound and can predict the growth outcomes for higher complexity combinations. Hence, the analysis demonstrates that the exhaustive power of the genome scale metabolic reconstruction allows capturing complexities that are beyond common biochemical expertise and knowledge and further support the importance of computational platforms for the educated design of complex media. The model presented here can potentially serve as a predictive tool towards achieving optimal biodegradation efficiencies and for the development of ecologically friendly solutions for pollutant degradation.

| S-EPMC7398907 | biostudies-literature

Evaluation of Arthrobacter aurescens Strain TC1 as Bioaugmentation Bacterium in Soils Contaminated with the Herbicidal Substance Terbuthylazine.

Project description:In the last years the chloro-s-triazine active substance terbuthylazine has been increasingly used as an herbicide and may leave residues in the environment which can be of concern. The present study aimed at developing a bioaugmentation tool based on the soil bacterium Arthrobacter aurescens strain TC1 for the remediation of terbuthylazine contaminated soils and at examining its efficacy for both soil and aquatic compartments. First, the feasibility of growing the bioaugmentation bacterium inocula on simple sole nitrogen sources (ammonium and nitrate) instead of atrazine, while still maintaining its efficiency to biodegrade terbuthylazine was shown. In sequence, the successful and quick (3 days) bioremediation efficacy of ammonium-grown A. aurescens TC1 cells was proven in a natural soil freshly spiked or four-months aged with commercial terbuthylazine at a dose 10× higher than the recommended in corn cultivation, to mimic spill situations. Ecotoxicity assessment of the soil eluates towards a freshwater microalga supported the effectiveness of the bioaugmentation tool. Obtained results highlight the potential to decontaminate soil while minimizing terbuthylazine from reaching aquatic compartments via the soil-water pathway. The usefulness of this bioaugmentation tool to provide rapid environment decontamination is particularly relevant in the event of accidental high herbicide contamination. Its limitations and advantages are discussed.

| S-EPMC4684385 | biostudies-literature

Paenarthrobacter aurescens TC1

Project description:Breaks down s-triazine compounds in contaminated environments

| PRJNA12512 | ENA

X-ray structure and mutational analysis of the atrazine Chlorohydrolase TrzN.

Project description:Atrazine chlorohydrolase, TrzN (triazine hydrolase or atrazine chlorohydrolase 2), initiates bacterial metabolism of the herbicide atrazine by hydrolytic displacement of a chlorine substituent from the s-triazine ring. The present study describes crystal structures and reactivity of wild-type and active site mutant TrzN enzymes. The homodimer native enzyme structure, solved to 1.40 ? resolution, is a (??)(8) barrel, characteristic of members of the amidohydrolase superfamily. TrzN uniquely positions threonine 325 in place of a conserved aspartate that ligates the metal in most mononuclear amidohydrolases superfamily members. The threonine side chain oxygen atom is 3.3 ? from the zinc atom and 2.6 ? from the oxygen atom of zinc-coordinated water. Mutation of the threonine to a serine resulted in a 12-fold decrease in k(cat)/K(m), largely due to k(cat), whereas the T325D and T325E mutants had immeasurable activity. The structure and kinetics of TrzN are reminiscent of carbonic anhydrase, which uses a threonine to assist in positioning water for reaction with carbon dioxide. An isosteric substitution in the active site glutamate, E241Q, showed a large diminution in activity with ametryn, no detectable activity with atratone, and a 10-fold decrease with atrazine, when compared with wild-type TrzN. Activity with the E241Q mutant was nearly constant from pH 6.0 to 10.0, consistent with the loss of a proton-donating group. Structures for TrzN-E241Q were solved with bound ametryn and atratone to 1.93 and 1.64 ? resolution, respectively. Both structure and kinetic determinations suggest that the Glu(241) side chain provides a proton to N-1 of the s-triazine substrate to facilitate nucleophilic displacement at the adjacent C-2.

| S-EPMC2945555 | biostudies-literature

Structures of a γ-aminobutyrate (GABA) transaminase from the s-triazine-degrading organism Arthrobacter aurescens TC1 in complex with PLP and with its external aldimine PLP-GABA adduct.

Project description:Two complex structures of the γ-aminobutyrate (GABA) transaminase A1R958 from Arthrobacter aurescens TC1 are presented. The first, determined to a resolution of 2.80 Å, features the internal aldimine formed by reaction between the ℇ-amino group of Lys295 and the cofactor pyridoxal phosphate (PLP); the second, determined to a resolution of 2.75 Å, features the external aldimine adduct formed between PLP and GABA in the first half-reaction. This is the first structure of a microbial GABA transaminase in complex with its natural external aldimine and reveals the molecular determinants of GABA binding in this enzyme.

| S-EPMC3497974 | biostudies-literature

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