scholarly journals A Novel Degradation Mechanism for Pyridine Derivatives inAlcaligenes faecalisJQ135

2018 ◽  
Vol 84 (15) ◽  
Author(s):  
Jiguo Qiu ◽  
Bin Liu ◽  
Lingling Zhao ◽  
Yanting Zhang ◽  
Dan Cheng ◽  
...  
Keyword(s):  
Nicotinic Acid ◽  
Maleic Acid ◽  
Degradation Mechanism ◽  
Picolinic Acid ◽  
Alcaligenes Faecalis ◽  
Pyridine Derivative ◽  
Pyridine Derivatives ◽  
Monooxygenase Activity ◽  
Content Type ◽  
Gene Coding

ABSTRACT5-Hydroxypicolinic acid (5HPA), a natural pyridine derivative, is microbially degraded in the environment. However, the physiological, biochemical, and genetic foundations of 5HPA metabolism remain unknown. In this study, an operon (hpa), responsible for 5HPA degradation, was cloned fromAlcaligenes faecalisJQ135. HpaM was a monocomponent flavin adenine dinucleotide (FAD)-dependent monooxygenase and shared low identity (only 28 to 31%) with reported monooxygenases. HpaM catalyzed theorthodecarboxylative hydroxylation of 5HPA, generating 2,5-dihydroxypyridine (2,5DHP). The monooxygenase activity of HpaM was FAD and NADH dependent. The apparentKmvalues of HpaM for 5HPA and NADH were 45.4 μM and 37.8 μM, respectively. The geneshpaX,hpaD, andhpaFwere found to encode 2,5DHP dioxygenase,N-formylmaleamic acid deformylase, and maleamate amidohydrolase, respectively; however, the three genes were not essential for 5HPA degradation inA. faecalisJQ135. Furthermore, the genemaiA, which encodes a maleic acidcis-transisomerase, was essential for the metabolism of 5HPA, nicotinic acid, and picolinic acid inA. faecalisJQ135, indicating that it might be a key gene in the metabolism of pyridine derivatives. The genes and proteins identified in this study showed a novel degradation mechanism of pyridine derivatives.IMPORTANCEUnlike the benzene ring, the uneven distribution of the electron density of the pyridine ring influences the positional reactivity and interaction with enzymes; e.g., theorthoandparaoxidations are more difficult than themetaoxidations. Hydroxylation is an important oxidation process for the pyridine derivative metabolism. In previous reports, theorthohydroxylations of pyridine derivatives were catalyzed by multicomponent molybdenum-containing monooxygenases, while themetahydroxylations were catalyzed by monocomponent FAD-dependent monooxygenases. This study identified the new monocomponent FAD-dependent monooxygenase HpaM that catalyzed theorthodecarboxylative hydroxylation of 5HPA. In addition, we found that themaiAgene coding for maleic acidcis-transisomerase was pivotal for the metabolism of 5HPA, nicotinic acid, and picolinic acid inA. faecalisJQ135. This study provides novel insights into the microbial metabolism of pyridine derivatives.

scholarly journals Novel 3,6-Dihydroxypicolinic Acid Decarboxylase-Mediated Picolinic Acid Catabolism inAlcaligenes faecalisJQ135

2019 ◽  
Vol 201 (7) ◽  
Author(s):  
Jiguo Qiu ◽  
Yanting Zhang ◽  
Shigang Yao ◽  
Hao Ren ◽  
Meng Qian ◽  
...  
Keyword(s):  
Aromatic Compounds ◽  
Picolinic Acid ◽  
Alcaligenes Faecalis ◽  
Degradation Pathway ◽  
Site Directed Mutagenesis ◽  
Pyridine Derivative ◽  
Acid Decarboxylase ◽  
Microbial Cells ◽  
Content Type ◽  
Related Proteins

ABSTRACTPicolinic acid (PA), a typical C-2-carboxylated pyridine derivative, is a metabolite ofl-tryptophan and many other aromatic compounds in mammalian and microbial cells. Microorganisms can degrade and utilize PA for growth. However, the precise mechanism of PA metabolism remains unknown.Alcaligenes faecalisstrain JQ135 utilizes PA as its carbon and nitrogen source for growth. In this study, we screened a 6-hydroxypicolinic acid (6HPA) degradation-deficient mutant through random transposon mutagenesis. The mutant hydroxylated 6HPA into an intermediate, identified as 3,6-dihydroxypicolinic acid (3,6DHPA), with no further degradation. A novel decarboxylase, PicC, was identified to be responsible for the decarboxylation of 3,6DHPA to 2,5-dihydroxypyridine. Although, PicC belonged to the amidohydrolase 2 family, it shows low similarity (<45%) compared to other reported amidohydrolase 2 family decarboxylases. Moreover, PicC was found to form a monophyletic group in the phylogenetic tree constructed using PicC and related proteins. Further, the genetic deletion and complementation results demonstrated thatpicCwas essential for PA degradation. The PicC was Zn2+-dependent nonoxidative decarboxylase that can specifically catalyze the irreversible decarboxylation of 3,6DHPA to 2,5-dihydroxypyridine. TheKmandkcattoward 3,6DHPA were observed to be 13.44 μM and 4.77 s−1, respectively. Site-directed mutagenesis showed that His163 and His216 were essential for PicC activity. This study provides new insights into the microbial metabolism of PA at molecular level.IMPORTANCEPicolinic acid is a natural toxic pyridine derived froml-tryptophan metabolism and other aromatic compounds in mammalian and microbial cells. Microorganisms can degrade and utilize picolinic acid for their growth, and thus a microbial degradation pathway of picolinic acid has been proposed. Picolinic acid is converted into 6-hydroxypicolinic acid, 3,6-dihydroxypicolinic acid, and 2,5-dihydroxypyridine in turn. However, there was no physiological and genetic validation for this pathway. This study demonstrated that 3,6-dihydroxypicolinic acid was an intermediate in picolinic acid catabolism and further identified and characterized a novel amidohydrolase 2 family decarboxylase PicC. PicC was also shown to catalyze the decarboxylation of 3,6-dihydroxypicolinic acid into 2,5-dihydroxypyridine. This study provides a basis for understanding picolinic acid degradation and its underlying molecular mechanism.

scholarly journals The Novel Monocomponent FAD-dependent Monooxygenase HpaM Catalyzes the 2-Decarboxylative Hydroxylation of 5-Hydroxypicolinic Acid inAlcaligenes faecalisJQ135

2017 ◽  
Author(s):  
Jiguo Qiu ◽  
Bin Liu ◽  
Lingling Zhao ◽  
Yanting Zhang ◽  
Dan Cheng ◽  
...  
Keyword(s):  
Gene Cluster ◽  
Microbial Degradation ◽  
Pyridine Ring ◽  
Degradation Process ◽  
Alcaligenes Faecalis ◽  
Pyridine Derivative ◽  
Pyridine Derivatives ◽  
Monooxygenase Activity ◽  
E Coli ◽  
Transformation Mechanisms

Abstract5-hydroxypicolinic acid (5HPA) is a natural pyridine derivative that can be microbially degraded. However, the physiological, biochemical, and genetic foundation of the microbial catabolism of 5HPA remains unknown. In this study, a gene clusterhpa(which is involved in degradation of 5HPA inAlcaligenes faecalisJQ135) was cloned and HpaM was identified as a novel monocomponent FAD-dependent monooxygenase. HpaM shared a sequence only 31% similarity with the most related protein 6-hydroxynicotinate 3-monooxygenase (NicC) ofPseudomonas putidaKT2440.hpaMwas heterologously expressed inE. coliBL21(DE3), and the recombinant HpaM was purified via Ni-affinity chromatography. HpaM catalyzed the 2-decarboxylative hydroxylation of 5-HPA, thus generating 2,5-dihydroxypyridine (2,5-DPH). Monooxygenase activity was only detected in the presence of FAD and NADH, but not of FMN and NADPH. The apparentKmvalues of HpaM toward 5HPA and NADH were 45.4 μ and 37.8 μ, respectively. Results of gene deletion and complementation showed thathpaMwas essential for 5HPA degradation inAlcaligenes faecalisJQ135.ImportancePyridine derivatives are ubiquitous in nature and important chemical materials that are currently widely used in agriculture, pharmaceutical, and chemical industries. Thus, the microbial degradation and transformation mechanisms of pyridine derivatives received considerable attention. Decarboxylative hydroxylation was an important degradation process in pyridine derivatives, and previously reported decarboxylative hydroxylations happened in the C3 of the pyridine ring. In this study, we cloned the gene clusterhpa, which is responsible for 5HPA degradation inAlcaligenes faecalisJQ135, thus identifying a novel monocomponent FAD-dependent monooxygenase HpaM. Unlike 3-decarboxylative monooxygenases, HpaM catalyzed decarboxylative hydroxylation in the C2 of the pyridine ring in 5-hydroxypicolinic acid. These findings deepen our understanding of the molecular mechanism of microbial degradation of pyridine derivatives. Furthermore, HpaM offers potential for applications to transform useful pyridine derivatives.

scholarly journals Identification and Characterization of a NovelpicGene Cluster Responsible for Picolinic Acid Degradation inAlcaligenes faecalisJQ135

2019 ◽  
Vol 201 (16) ◽  
Author(s):  
Jiguo Qiu ◽  
Lingling Zhao ◽  
Siqiong Xu ◽  
Qing Chen ◽  
Le Chen ◽  
...  
Keyword(s):  
Gene Cluster ◽  
Molecular Mechanisms ◽  
Picolinic Acid ◽  
Gene Clusters ◽  
Alcaligenes Faecalis ◽  
Degradation Pathway ◽  
Pyridine Derivative ◽  
Organic Chemical ◽  
Content Type ◽  
New Perspective

ABSTRACTPicolinic acid (PA) is a natural toxic pyridine derivative. Microorganisms can degrade and utilize PA for growth. However, the full catabolic pathway of PA and its physiological and genetic foundation remain unknown. In this study, we identified a gene cluster, designatedpicRCEDFB4B3B2B1A1A2A3, responsible for the degradation of PA fromAlcaligenes faecalisJQ135. Our results suggest that PA degradation pathway occurs as follows: PA was initially 6-hydroxylated to 6-hydroxypicolinic acid (6HPA) by PicA (a PA dehydrogenase). 6HPA was then 3-hydroxylated by PicB, a four-component 6HPA monooxygenase, to form 3,6-dihydroxypicolinic acid (3,6DHPA), which was then converted into 2,5-dihydroxypyridine (2,5DHP) by the decarboxylase PicC. 2,5DHP was further degraded to fumaric acid through PicD (2,5DHP 5,6-dioxygenase), PicE (N-formylmaleamic acid deformylase), PicF (maleamic acid amidohydrolase), and PicG (maleic acid isomerase). Homologouspicgene clusters with diverse organizations were found to be widely distributed inAlpha-,Beta-, andGammaproteobacteria. Our findings provide new insights into the microbial catabolism of environmental toxic pyridine derivatives.IMPORTANCEPicolinic acid is a common metabolite ofl-tryptophan and some aromatic compounds and is an important intermediate in organic chemical synthesis. Although the microbial degradation/detoxification of picolinic acid has been studied for over 50 years, the underlying molecular mechanisms are still unknown. Here, we show that thepicgene cluster is responsible for the complete degradation of picolinic acid. Thepicgene cluster was found to be widespread in otherAlpha-,Beta-, andGammaproteobacteria. These findings provide a new perspective for understanding the catabolic mechanisms of picolinic acid in bacteria.

scholarly journals Identification and characterization of a novelpicgene cluster responsible for picolinic acid degradation inAlcaligenes faecalisJQ135

2019 ◽  
Author(s):  
Jiguo Qiu ◽  
Lingling Zhao ◽  
Siqiong Xu ◽  
Qing Chen ◽  
Le Chen ◽  
...  
Keyword(s):  
Gene Cluster ◽  
Molecular Mechanisms ◽  
Tricarboxylic Acid Cycle ◽  
Picolinic Acid ◽  
Gene Clusters ◽  
Alcaligenes Faecalis ◽  
Pyridine Derivative ◽  
Complete Degradation ◽  
Important Intermediate ◽  
New Perspective

AbstractPicolinic acid (PA) is a natural toxic pyridine derivative. Microorganisms can degrade and utilize PA for growth. However, the full metabolic pathway and its physiological and genetic foundation remain unknown. In this study, we identified thepicgene cluster responsible for the complete degradation of PA fromAlcaligenes faecalisJQ135. PA was initially 6-hydroxylated into 6-hydroxypicolinic acid (6HPA) by PA dehydrogenase (PicA). 6HPA was then 3-hydroxylated by a four-component 6HPA monooxygenase (PicB) to form 3,6-dihydroxypicolinic acid (3,6DHPA), which was then converted into 2,5-dihydroxypyridine (2,5DHP) by a decarboxylase (PicC). The 2,5DHP was further degraded into fumaric acid, through PicD (2,5DHP dioxygenase), PicE (N-formylmaleamic acid deformylase), PicF (maleamic acid amidohydrolase), and PicG (maleic acid isomerase). Homologouspicgene clusters with diverse organizations were found to be widely distributed inα-,β-, andγ-Proteobacteria. Our findings provide new insights into the microbial metabolism of environmental toxic pyridine derivatives.ImportancePicolinic acid is a common metabolite of L-tryptophan and some aromatic compounds and is an important intermediate of industrial concern. Although the microbial degradation/detoxification of picolinic acid has been studied for over 50 years, the underlying molecular mechanisms are still unknown. Here, we show thepicgene cluster responsible for the complete degradation of picolinic acid into the tricarboxylic acid cycle. This gene cluster was found to be widespread in otherα-,β-, andγ-Proteobacteria. These findings provide new perspective for understanding the mechanisms of picolinic acid biodegradation in bacteria.

scholarly journals Mirror-Like Bright Al-Mn Coatings Electrodeposition from 1-Ethyl-3 Methylimidazolium Chloride-AlCl3-MnCl2 Ionic Liquids with Pyridine Derivatives

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6226
Author(s):  
Dong Peng ◽  
Dalong Cong ◽  
Kaiqiang Song ◽  
Xingxing Ding ◽  
Xuan Wang ◽  
...  
Keyword(s):  
Ionic Liquids ◽  
Picolinic Acid ◽  
Protective Layer ◽  
Nanocrystalline Structure ◽  
Pyridine Derivative ◽  
Pyridine Derivatives ◽  
X Ray Diffraction ◽  
X Ray ◽  
Superior Corrosion Resistance ◽  
Better Than

The effects of three pyridine derivative additives, 4-hydroxypyridine, 4-picolinic acid, and 4-cyanopyridine, on Al-Mn coatings were investigated in 1-ethyl-3-methylimidazolium chloride-AlCl3-MnCl2 (EMIC-AlCl3-MnCl2) ionic liquids. The smooth mirror-like bright Al-Mn coatings were obtained only in the EMIC-AlCl3-MnCl2 ionic liquids containing 4-cyanopyridine, while the matte Al-Mn coatings were electrodeposited from EMIC-AlCl3-MnCl2 without additives or containing either 4-hydroxypyridine or 4-picolinic acid. The scanning electron microscope and X-ray diffraction showed that the bright Al-Mn coatings consisted of nanocrystals and had a strong (200) preferential orientation, while the particle size of matte Al-Mn coatings were within the micron range. The brightening mechanism of 4-cyanopyridine is due to it being adsorbed onto the cathode to produce the combined effect of (1) generating an overpotential to promote Al-Mn nucleation; (2) inhibiting the growth of the deposited nuclei and enabling them grow preferentially, making the coating composed of nanocrystals and with a smooth surface. The brightening effect of 4-cyanopyridine on the Al-Mn coatings was far better than that of the 4-hydroxypyridine and the 4-picolinic acid. In addition, the bright Al-Mn coating was prepared in a bath with 6 mmol·L−1 4-cyanopyridine and displayed superior corrosion resistance relative to the matte coatings, which could be attributed to its unique nanocrystalline structure that increased the number of grain boundaries and accelerated the formation of the protective layer of the corrosion products.

scholarly journals Methanobactin from Methylocystis sp. Strain SB2 Affects Gene Expression and Methane Monooxygenase Activity in Methylosinus trichosporium OB3b

2015 ◽  
Vol 81 (7) ◽  
pp. 2466-2473 ◽  
Author(s):  
Muhammad Farhan Ul-Haque ◽  
Bhagyalakshmi Kalidass ◽  
Alexey Vorobev ◽  
Bipin S. Baral ◽  
Alan A. DiSpirito ◽  
...  
Keyword(s):  
Gene Expression ◽  
Methane Monooxygenase ◽  
Particulate Methane Monooxygenase ◽  
Methylosinus Trichosporium Ob3b ◽  
Methylosinus Trichosporium ◽  
Monooxygenase Activity ◽  
Content Type ◽  
Soluble Methane Monooxygenase ◽  
A Subunit ◽  
Membrane Bound

ABSTRACTMethanotrophs can express a cytoplasmic (soluble) methane monooxygenase (sMMO) or membrane-bound (particulate) methane monooxygenase (pMMO). Expression of these MMOs is strongly regulated by the availability of copper. Many methanotrophs have been found to synthesize a novel compound, methanobactin (Mb), that is responsible for the uptake of copper, and methanobactin produced byMethylosinus trichosporiumOB3b plays a key role in controlling expression of MMO genes in this strain. As all known forms of methanobactin are structurally similar, it was hypothesized that methanobactin from one methanotroph may alter gene expression in another. WhenMethylosinus trichosporiumOB3b was grown in the presence of 1 μM CuCl2, expression ofmmoX, encoding a subunit of the hydroxylase component of sMMO, was very low.mmoXexpression increased, however, when methanobactin fromMethylocystissp. strain SB2 (SB2-Mb) was added, as did whole-cell sMMO activity, but there was no significant change in the amount of copper associated withM. trichosporiumOB3b. IfM. trichosporiumOB3b was grown in the absence of CuCl2, themmoXexpression level was high but decreased by several orders of magnitude if copper prebound to SB2-Mb (Cu-SB2-Mb) was added, and biomass-associated copper was increased. Exposure ofMethylosinus trichosporiumOB3b to SB2-Mb had no effect on expression ofmbnA, encoding the polypeptide precursor of methanobactin in either the presence or absence of CuCl2.mbnAexpression, however, was reduced when Cu-SB2-Mb was added in both the absence and presence of CuCl2. These data suggest that methanobactin acts as a general signaling molecule in methanotrophs and that methanobactin “piracy” may be commonplace.

Multinuclear NMR spectra of [Pt(L)Cl3]− (L = pyridine derivatives) complexes and crystal structure of trans-Pt(2,6-di(hydroxymethyl)pyridine)2Cl2•2H2O

1996 ◽  
Vol 74 (11) ◽  
pp. 2121-2130 ◽  
Author(s):  
Fernande D. , ◽  
Corinne Bensimon ◽  
André L. Beauchamp
Keyword(s):  
Crystal Structure ◽  
Pyridine Ring ◽  
Chemical Shifts ◽  
Bond Distance ◽  
Coupling Constants ◽  
Mirror Plane ◽  
Pyridine Derivative ◽  
Pyridine Derivatives ◽  
Pyridine Ligand ◽  
Twofold Axis

Complexes of the type [Pt(L)Cl3]− (L = pyridine derivative) were synthesized and studied by 13C and 195Pt NMR spectroscopies. The 195Pt signals were observed between −1720 and −1897 ppm. No correlation between the δ(Pt) and the pKa of the protonated pyridine derivatives was found. The chemical shifts vary with the substituents on the pyridine ligand. Compounds with substituents in ortho positions were observed at lower fields, except for complexes containing hydroxy or amine groups. The latter compounds were observed at higher fields, close to the signals of the Pt-unsubstituted pyridine compound. These results were explained in terms of the solvent effect. The chemical shifts δ(C) and the coupling constants J(13C–195Pt) were measured and the results interpreted with a view of obtaining information on the nature of the Pt—N bond. The possibility of π-bonding between platinum and the pyridine ligand is examined. The conformation of the pyridine ring in relation to the platinum plane and the energies of the rotation barriers around the Pt—N bond in these types of platinum(II) complexes are briefly discussed. The crystal structure of trans-Pt(2,6-(HOCH2)2py)2Cl2•2H2O was determined by X-ray diffraction. The compound is monoclinic, C2/m, a = 7.022(6), b = 15.646(13), c = 8.344(10) Å, β = 93.35(8)°, Z = 2, R = 0.037. The platinum atom is located at the junction of the twofold axis and the mirror plane, the N atoms and the para-C atom of the pyridine ring are situated on the twofold axis, and the chloride ligands are on the mirror plane. The compound crystallizes with molecules of water, which are H-bonded to the hydroxy groups. The Pt—Cl bond distance is 2.306(2) Å, and that of the Pt—N bond is 2.041 (6) Å. The dihedral angle between the platinum and the pyridine planes is 79.8°. Key words: platinum, pyridine derivatives, NMR, crystal structure.

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