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Laurent V, Gourbeyre L, Uzel A, Hélaine V, Nauton L, Traïkia M, de Berardinis V, Salanoubat M, Gefflaut T, Lemaire M, Guérard-Hélaine C. Pyruvate Aldolases Catalyze Cross-Aldol Reactions between Ketones: Highly Selective Access to Multi-Functionalized Tertiary Alcohols. ACS Catal 2020. [DOI: 10.1021/acscatal.9b05512] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Victor Laurent
- Université Clermont Auvergne, CNRS, SIGMA Clermont, Institut de Chimie de Clermont-Ferrand, 63000 Clermont-Ferrand, France
| | - Léa Gourbeyre
- Université Clermont Auvergne, CNRS, SIGMA Clermont, Institut de Chimie de Clermont-Ferrand, 63000 Clermont-Ferrand, France
| | - Alexandre Uzel
- Université Clermont Auvergne, CNRS, SIGMA Clermont, Institut de Chimie de Clermont-Ferrand, 63000 Clermont-Ferrand, France
| | - Virgil Hélaine
- Université Clermont Auvergne, CNRS, SIGMA Clermont, Institut de Chimie de Clermont-Ferrand, 63000 Clermont-Ferrand, France
| | - Lionel Nauton
- Université Clermont Auvergne, CNRS, SIGMA Clermont, Institut de Chimie de Clermont-Ferrand, 63000 Clermont-Ferrand, France
| | - Mounir Traïkia
- Université Clermont Auvergne, CNRS, SIGMA Clermont, Institut de Chimie de Clermont-Ferrand, 63000 Clermont-Ferrand, France
| | - Véronique de Berardinis
- Génomique Métabolique, Génoscope, Institut François Jacob, CEA, CNRS, Univ Evry, Université Paris-Saclay, 91057 Evry, France
| | - Marcel Salanoubat
- Génomique Métabolique, Génoscope, Institut François Jacob, CEA, CNRS, Univ Evry, Université Paris-Saclay, 91057 Evry, France
| | - Thierry Gefflaut
- Université Clermont Auvergne, CNRS, SIGMA Clermont, Institut de Chimie de Clermont-Ferrand, 63000 Clermont-Ferrand, France
| | - Marielle Lemaire
- Université Clermont Auvergne, CNRS, SIGMA Clermont, Institut de Chimie de Clermont-Ferrand, 63000 Clermont-Ferrand, France
| | - Christine Guérard-Hélaine
- Université Clermont Auvergne, CNRS, SIGMA Clermont, Institut de Chimie de Clermont-Ferrand, 63000 Clermont-Ferrand, France
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Zhou NA, Kjeldal H, Gough HL, Nielsen JL. Identification of Putative Genes Involved in Bisphenol A Degradation Using Differential Protein Abundance Analysis of Sphingobium sp. BiD32. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:12232-41. [PMID: 26390302 DOI: 10.1021/acs.est.5b02987] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Discharge of the endocrine disrupting compound bisphenol A (BPA) with wastewater treatment plant (WWTP) effluents into surface waters results in deleterious effects on aquatic life. Sphingobium sp. BiD32 was previously isolated from activated sludge based on its ability to degrade BPA. This study investigated BPA metabolism by Sphingobium sp. BiD32 using label-free quantitative proteomics. The genome of Sphingobium sp. BiD32 was sequenced to provide a species-specific platform for optimal protein identification. The bacterial proteomes of Sphingobium sp. BiD32 in the presence and absence of BPA were identified and quantified. A total of 2155 proteins were identified; 1174 of these proteins were quantified, and 184 of these proteins had a statistically significant change in abundance in response to the presence/absence of BPA (p ≤ 0.05). Proteins encoded by genes previously identified to be responsible for protocatechuate degradation were upregulated in the presence of BPA. The analysis of the metabolites from BPA degradation by Sphingobium sp. BiD32 detected a hydroxylated metabolite. A novel p-hydroxybenzoate hydroxylase enzyme detected by proteomics was implicated in the metabolic pathway associated with the detected metabolite. This enzyme is hypothesized to be involved in BPA degradation by Sphingobium sp. BiD32, and may serve as a future genetic marker for BPA degradation.
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Affiliation(s)
- Nicolette A Zhou
- Department of Chemistry and Bioscience, Aalborg University , Fredrik Bajers Vej 7H, DK-9220 Aalborg, Denmark
- Department of Civil and Environmental Engineering, University of Washington , More Hall 201 Box 352700, Seattle, Washington 98195-2700, United States
| | - Henrik Kjeldal
- Department of Chemistry and Bioscience, Aalborg University , Fredrik Bajers Vej 7H, DK-9220 Aalborg, Denmark
| | - Heidi L Gough
- Department of Civil and Environmental Engineering, University of Washington , More Hall 201 Box 352700, Seattle, Washington 98195-2700, United States
| | - Jeppe L Nielsen
- Department of Chemistry and Bioscience, Aalborg University , Fredrik Bajers Vej 7H, DK-9220 Aalborg, Denmark
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Simkhada D, Zhang H, Mori S, Williams H, Watanabe CMH. Activation of cryptic metabolite production through gene disruption: Dimethyl furan-2,4-dicarboxylate produced by Streptomyces sahachiroi. Beilstein J Org Chem 2013; 9:1768-73. [PMID: 24062841 PMCID: PMC3778384 DOI: 10.3762/bjoc.9.205] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2013] [Accepted: 08/09/2013] [Indexed: 01/23/2023] Open
Abstract
At least 65% of all small molecule drugs on the market today are natural products, however, re-isolation of previously identified and characterized compounds has become a serious impediment to the discovery of new bioactive natural products. Here, genetic knockout of an unusual non-ribosomal peptide synthetase (NRPS) C-PCP-C module, aziA2, is performed resulting in the accumulation of the secondary metabolite, dimethyl furan-2,4-dicarboxylate. The cryptic metabolite represents the first non-azinomycin related compound to be isolated and characterized from the soil bacterium, S. sahachiroi. The results from this study suggest that abolishing production of otherwise predominant natural products through genetic knockout may constitute a means to “activate” the production of novel secondary metabolites that would otherwise lay dormant within microbial genome sequences.
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Affiliation(s)
- Dinesh Simkhada
- Texas A&M University, Department of Chemistry, College Station, TX 77843, USA
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Ni B, Zhang Y, Chen DW, Wang BJ, Liu SJ. Assimilation of aromatic compounds by Comamonas testosteroni: characterization and spreadability of protocatechuate 4,5-cleavage pathway in bacteria. Appl Microbiol Biotechnol 2012; 97:6031-41. [DOI: 10.1007/s00253-012-4402-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Revised: 08/25/2012] [Accepted: 08/29/2012] [Indexed: 10/27/2022]
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Paliwal R, Rawat AP, Rawat M, Rai JPN. Bioligninolysis: recent updates for biotechnological solution. Appl Biochem Biotechnol 2012; 167:1865-89. [PMID: 22639362 DOI: 10.1007/s12010-012-9735-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2012] [Accepted: 05/10/2012] [Indexed: 10/28/2022]
Abstract
Bioligninolysis involves living organisms and/or their products in degradation of lignin, which is highly resistant, plant-originated polymer having three-dimensional network of dimethoxylated (syringyl), monomethoxylated (guaiacyl), and non-methoxylated (p-hydroxyphenyl) phenylpropanoid and acetylated units. As a major repository of aromatic chemical structures on earth, lignin bears paramount significance for its removal owing to potential application of bioligninolytic systems in industrial production. Early reports illustrating the discovery and cloning of ligninolytic biocatalysts in fungi was truly a landmark in the field of enzymatic delignification. However, the enzymology for bacterial delignification is hitherto poorly understood. Moreover, the lignin-degrading bacterial genes are still unknown and need further exploration. This review deals with the current knowledge about ligninolytic enzyme families produced by fungi and bacteria, their mechanisms of action, and genetic regulation and reservations, which render them attractive candidates in biotechnological applications.
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Affiliation(s)
- Rashmi Paliwal
- Ecotechnology Laboratory, Department of Environmental Science, G.B.Pant. University of Agriculture and Technology, Pantnagar 263145, India
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Bugg TDH, Ahmad M, Hardiman EM, Rahmanpour R. Pathways for degradation of lignin in bacteria and fungi. Nat Prod Rep 2011; 28:1883-96. [PMID: 21918777 DOI: 10.1039/c1np00042j] [Citation(s) in RCA: 457] [Impact Index Per Article: 35.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Lignin is a heterogeneous aromatic polymer found as 10-35% of lignocellulose, found in plant cell walls. The bio-conversion of plant lignocellulose to glucose is an important part of second generation biofuel production, but the resistance of lignin to breakdown is a major obstacle in this process, hence there is considerable interest in the microbial breakdown of lignin. White-rot fungi are known to break down lignin with the aid of extracellular peroxidase and laccase enzymes. There are also reports of bacteria that can degrade lignin, and recent work indicates that bacterial lignin breakdown may be more significant than previously thought. The review will discuss the enzymes for lignin breakdown in fungi and bacteria, and the catabolic pathways for breakdown of the β-aryl ether, biphenyl and other components of lignin in bacteria and fungi. The review will also discuss small molecule phenolic breakdown products from lignin that have been identified from lignin-degrading microbes, and includes a bioinformatic analysis of the occurrence of known lignin-degradation pathways in Gram-positive and Gram-negative bacteria.
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Wang W, Mazurkewich S, Kimber MS, Seah SYK. Structural and kinetic characterization of 4-hydroxy-4-methyl-2-oxoglutarate/4-carboxy-4-hydroxy-2-oxoadipate aldolase, a protocatechuate degradation enzyme evolutionarily convergent with the HpaI and DmpG pyruvate aldolases. J Biol Chem 2010; 285:36608-15. [PMID: 20843800 PMCID: PMC2978589 DOI: 10.1074/jbc.m110.159509] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2010] [Revised: 09/03/2010] [Indexed: 11/06/2022] Open
Abstract
4-Hydroxy-4-methyl-2-oxoglutarate/4-carboxy-4-hydroxy-2-oxoadipate (HMG/CHA) aldolase from Pseudomonas putida F1 catalyzes the last step of the bacterial protocatechuate 4,5-cleavage pathway. The preferred substrates of the enzyme are 2-keto-4-hydroxy acids with a 4-carboxylate substitution. The enzyme also exhibits oxaloacetate decarboxylation and pyruvate α-proton exchange activity. Sodium oxalate is a competitive inhibitor of the aldolase reaction. The pH dependence of k(cat)/K(m) and k(cat) for the enzyme is consistent with a single deprotonation with pK(a) values of 8.0 ± 0.1 and 7.0 ± 0.1 for free enzyme and enzyme substrate complex, respectively. The 1.8 Å x-ray structure shows a four-layered α-β-β-α sandwich structure with the active site at the interface of two adjacent subunits of a hexamer; this fold resembles the RNase E inhibitor, RraA, but is novel for an aldolase. The catalytic site contains a magnesium ion ligated by Asp-124 as well as three water molecules bound by Asp-102 and Glu-199'. A pyruvate molecule binds the magnesium ion through both carboxylate and keto oxygen atoms, completing the octahedral geometry. The carbonyl oxygen also forms hydrogen bonds with the guanadinium group of Arg-123, which site-directed mutagenesis confirms is essential for catalysis. A mechanism for HMG/CHA aldolase is proposed on the basis of the structure, kinetics, and previously established features of other aldolase mechanisms.
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Affiliation(s)
- Weijun Wang
- From the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Scott Mazurkewich
- From the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Matthew S. Kimber
- From the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Stephen Y. K. Seah
- From the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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Nogales J, Canales A, Jiménez-Barbero J, Serra B, Pingarrón JM, García JL, Díaz E. Unravelling the gallic acid degradation pathway in bacteria: the gal cluster from Pseudomonas putida. Mol Microbiol 2010; 79:359-74. [PMID: 21219457 DOI: 10.1111/j.1365-2958.2010.07448.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Gallic acid (3,4,5-trihydroxybenzoic acid, GA) is widely distributed in nature, being a major phenolic pollutant and a commonly used antioxidant and building-block for drug development. We have characterized the first complete cluster (gal genes) responsible for growth in GA in a derivative of the model bacterium Pseudomonas putida KT2440. GalT mediates specific GA uptake and chemotaxis, and highlights the critical role of GA transport in bacterial adaptation to GA consumption. The proposed GA degradation via the central intermediate 4-oxalomesaconic acid (OMA) was revisited and all enzymes involved have been identified. Thus, GalD is the prototype of a new subfamily of isomerases that catalyses a biochemical step that remained unknown, i.e. the tautomerization of the OMAketo generated by the GalA dioxygenase to OMAenol. GalB is the founding member of a new family of zinc-containing hydratases that converts OMAenol into 4-carboxy-4-hydroxy-2-oxoadipic acid (CHA). galC encodes the aldolase catalysing CHA cleavage to pyruvic and oxaloacetic acids. The presence of homologous gal clusters outside the Pseudomonas genus sheds light on the evolution and ecology of the gal genes in GA degraders. The gal genes were used for expanding the metabolic abilities of heterologous hosts towards GA degradation, and for engineering a GA cellular biosensor.
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Affiliation(s)
- Juan Nogales
- Department of Environmental Biology, Centro de Investigaciones Biológicas, CSIC. Ramiro de Maeztu 9, 28040 Madrid, Spain
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Characterization of the protocatechuate 4,5-cleavage pathway operon in Comamonas sp. strain E6 and discovery of a novel pathway gene. Appl Environ Microbiol 2010; 76:8093-101. [PMID: 20952641 DOI: 10.1128/aem.01863-10] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The protocatechuate (PCA) 4,5-cleavage (PCA45) pathway is the essential catabolic route for the degradation of various aromatic acids in the genus Comamonas. All of the PCA45 pathway genes, orf1-pmdKEFDABC, as well as another PCA 4,5-dioxygenase gene, pmdA(II)B(II), were isolated from a phthalate-degrading bacterium, Comamonas sp. strain E6. Disruption of pmdB and pmdD in E6, which code for the β subunit of PCA 4,5-dioxygenase and 2-pyrone-4,6-dicarboxylate (PDC) hydrolase, respectively, resulted in a growth defect on PCA, indicating that these genes are essential for the growth of E6 on PCA. On the other hand, inactivation of pmdB(II) did not affect the growth of E6 on PCA. Disruption of pmdK, which is related to a 4-hydroxybenzoate/PCA transporter of Pseudomonas putida, resulted in growth retardation on PCA. The insertional inactivation of orf1 in E6, whose deduced amino acid sequence has no similarity with proteins of known function, led to the complete loss of growth on PCA and the accumulation of PDC and 4-oxalomesaconate (OMA) from PCA. These results indicated the involvement of orf1 in the PCA45 pathway, and this gene, designated pmdU, was suggested to code for OMA tautomerase. Reverse transcription-PCR analysis suggested that the pmdUKEFDABC genes constitute an operon. The transcription start site of the pmd operon was mapped at 167 nucleotides upstream of the initiation codon of pmdU. The pmd promoter activity was enhanced 20-fold when the cells were grown in the presence of PCA. Inducers of the pmd operon were found to be PCA and PDC, but PDC was the more effective inducer.
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Regulatory system of the protocatechuate 4,5-cleavage pathway genes essential for lignin downstream catabolism. J Bacteriol 2010; 192:3394-405. [PMID: 20435721 DOI: 10.1128/jb.00215-10] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Sphingobium sp. strain SYK-6 converts various lignin-derived biaryls with guaiacyl (4-hydroxy-3-methoxyphenyl) and syringyl (4-hydroxy-3,5-dimethoxyphenyl) moieties to vanillate and syringate. These compounds are further catabolized through the protocatechuate (PCA) 4,5-cleavage (PCA45) pathway. In this article, the regulatory system of the PCA45 pathway is described. A LysR-type transcriptional regulator (LTTR), LigR, activated the transcription of the ligK-orf1-ligI-lsdA and ligJABC operons in the presence of PCA or gallate (GA), which is an intermediate metabolite of vanillate or syringate, respectively, and repressed transcription of its own gene. LigR bound to the positions -77 to -51 and -80 to -48 of the ligK and ligJ promoters, respectively, and induced DNA bending. In the presence of PCA or GA, DNA bending on both promoters was enhanced. The LigR-binding regions of the ligK and ligJ promoters in the presence of inducer molecules were extended and shortened, respectively. The LTTR consensus sequences (Box-K and Box-J) in the ligK and ligJ promoters were essential for the binding of LigR and transcriptional activation of both operons. In addition, the regions between the LigR binding boxes and the -35 regions were required for the enhancement of DNA bending, although the binding of LigR to the -35 region of the ligJ promoter was not observed in DNase I footprinting experiments. This study shows the binding features of LigR on the ligK and ligJ promoters and explains how the PCA45 pathway genes are expressed during degradation of lignin-derived biaryls by this bacterium.
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Nordin K, Unell M, Jansson JK. Novel 4-chlorophenol degradation gene cluster and degradation route via hydroxyquinol in Arthrobacter chlorophenolicus A6. Appl Environ Microbiol 2005; 71:6538-44. [PMID: 16269679 PMCID: PMC1287742 DOI: 10.1128/aem.71.11.6538-6544.2005] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Arthrobacter chlorophenolicus A6, a previously described 4-chlorophenol-degrading strain, was found to degrade 4-chlorophenol via hydroxyquinol, which is a novel route for aerobic microbial degradation of this compound. In addition, 10 open reading frames exhibiting sequence similarity to genes encoding enzymes involved in chlorophenol degradation were cloned and designated part of a chlorophenol degradation gene cluster (cph genes). Several of the open reading frames appeared to encode enzymes with similar functions; these open reading frames included two genes, cphA-I and cphA-II, which were shown to encode functional hydroxyquinol 1,2-dioxygenases. Disruption of the cphA-I gene yielded a mutant that exhibited negligible growth on 4-chlorophenol, thereby linking the cph gene cluster to functional catabolism of 4-chlorophenol in A. chlorophenolicus A6. The presence of a resolvase pseudogene in the cph gene cluster together with analyses of the G+C content and codon bias of flanking genes suggested that horizontal gene transfer was involved in assembly of the gene cluster during evolution of the ability of the strain to grow on 4-chlorophenol.
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Affiliation(s)
- Karolina Nordin
- Department of Biochemistry and Biophysics, Stockholm University, Sweden
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Peng X, Masai E, Kasai D, Miyauchi K, Katayama Y, Fukuda M. A second 5-carboxyvanillate decarboxylase gene, ligW2, is important for lignin-related biphenyl catabolism in Sphingomonas paucimobilis SYK-6. Appl Environ Microbiol 2005; 71:5014-21. [PMID: 16151081 PMCID: PMC1214697 DOI: 10.1128/aem.71.9.5014-5021.2005] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2004] [Accepted: 04/01/2005] [Indexed: 11/20/2022] Open
Abstract
A lignin-related biphenyl compound, 5,5'-dehydrodivanillate (DDVA), is degraded to 5-carboxyvanillate (5CVA) by the enzyme reactions catalyzed by DDVA O-demethylase (LigX), meta-cleavage oxygenase (LigZ), and meta-cleavage compound hydrolase (LigY) in Sphingomonas paucimobilis SYK-6. 5CVA is then transformed to vanillate by a nonoxidative 5CVA decarboxylase and is further degraded through the protocatechuate 4,5-cleavage pathway. A 5CVA decarboxylase gene, ligW, was isolated from SYK-6 (X. Peng, E. Masai, H. Kitayama, K. Harada, Y, Katayama, and M. Fukuda, Appl. Environ. Microbiol. 68:4407-4415, 2002). However, disruption of ligW slightly affected the 5CVA decarboxylase activity and the growth rate on DDVA of the mutant, suggesting the presence of an alternative 5CVA decarboxylase gene. Here we isolated a second 5CVA decarboxylase gene, ligW2, which consists of a 1,050-bp open reading frame encoding a polypeptide with a molecular mass of 39,379 Da. The deduced amino acid sequence encoded by ligW2 exhibits 37% identity with the sequence encoded by ligW. Based on a gas chromatography-mass spectrometry analysis of the reaction product from 5CVA catalyzed by LigW2 in the presence of deuterium oxide, LigW2 was indicated to be a nonoxidative decarboxylase of 5CVA, like LigW. After disruption of ligW2, both the growth rate on DDVA and the 5CVA decarboxylase activity of the mutant were decreased to approximately 30% of the wild-type levels. The ligW ligW2 double mutant lost both the ability to grow on DDVA and the 5CVA decarboxylase activity. These results indicate that both ligW and ligW2 contribute to 5CVA degradation, although ligW2 plays the more important role in the growth of SYK-6 cells on DDVA.
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Affiliation(s)
- Xue Peng
- Nagaoka University of Technology, Nagaoka, Niigata 940-2188, Japan
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Monzingo AF, Gao J, Qiu J, Georgiou G, Robertus JD. The X-ray structure of Escherichia coli RraA (MenG), A protein inhibitor of RNA processing. J Mol Biol 2003; 332:1015-24. [PMID: 14499605 DOI: 10.1016/s0022-2836(03)00970-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The Escherichia coli protein regulator of RNase E activity A (RraA) has recently been shown to act as a trans-acting modulator of RNA turnover in bacteria; it binds to the essential endonuclease RNase E and inhibits RNA processing in vivo and in vitro. Here, we report the 2.0A X-ray structure of RraA. The structure reveals a ring-like trimer with a central cavity of approximately 12A in diameter. Based on earlier sequence analysis, RraA had been identified as a putative S-adenosylmethionine:2-demethylmenaquinone and was annotated as MenG. However, an analysis of the RraA structure shows that the protein lacks the structural motifs usually required for methylases. Comparison of the observed fold with that of other proteins (and domains) suggests that the RraA fold is an ancient platform that has been adapted for a wide range of functions. An analysis of the amino acid sequence shows that the E.coli RraA exhibits an ancient relationship to a family of aldolases.
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Affiliation(s)
- Arthur F Monzingo
- Institute for Cellular and Molecular Biology, 1 University Station, University of Texas at Austin, Austin, TX 78712, USA
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Hara H, Masai E, Miyauchi K, Katayama Y, Fukuda M. Characterization of the 4-carboxy-4-hydroxy-2-oxoadipate aldolase gene and operon structure of the protocatechuate 4,5-cleavage pathway genes in Sphingomonas paucimobilis SYK-6. J Bacteriol 2003; 185:41-50. [PMID: 12486039 PMCID: PMC141877 DOI: 10.1128/jb.185.1.41-50.2003] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The protocatechuate (PCA) 4,5-cleavage pathway is the essential metabolic route for degradation of low-molecular-weight products derived from lignin by Sphingomonas paucimobilis SYK-6. In the 10.5-kb EcoRI fragment carrying the genes for PCA 4,5-dioxygenase (ligAB), 2-pyrone-4,6-dicarboxylate hydrolase (ligI), 4-oxalomesaconate hydratase (ligJ), and a part of 4-carboxy-2-hydroxymuconate-6-semialdehyde dehydrogenase (ligC), we found the ligK gene, which encodes 4-carboxy-4-hydroxy-2-oxoadipate (CHA) aldolase. The ligK gene was located 1,183 bp upstream of ligI and transcribed in the same direction as ligI. We also found the ligR gene encoding a LysR-type transcriptional activator, which was located 174 bp upstream of ligK. The ligK gene consists of a 684-bp open reading frame encoding a polypeptide with a molecular mass of 24,131 Da. The deduced amino acid sequence of ligK showed 57 to 88% identity with those of the corresponding genes recently reported in Sphingomonas sp. strain LB126, Comamonas testosteroni BR6020, Arthrobacter keyseri 12B, and Pseudomonas ochraceae NGJ1. The ligK gene was expressed in Escherichia coli, and the gene product (LigK) was purified to near homogeneity. Electrospray-ionization mass spectrometry indicated that LigK catalyzes not only the conversion of CHA to pyruvate and oxaloacetate but also that of oxaloacetate to pyruvate and CO(2). LigK is a hexamer, and its isoelectric point is 5.1. The K(m) for CHA and oxaloacetate are 11.2 and 136 micro M, respectively. Inactivation of ligK in S. paucimobilis SYK-6 resulted in the growth deficiency of vanillate and syringate, indicating that ligK encodes the essential CHA aldolase for catabolism of these compounds. Reverse transcription-PCR analysis revealed that the PCA 4,5-cleavage pathway genes of S. paucimobilis SYK-6 consisted of four transcriptional units, including the ligK-orf1-ligI-lsdA cluster, the ligJAB cluster, and the monocistronic ligR and ligC genes.
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Affiliation(s)
- Hirofumi Hara
- Department of Bioengineering, Nagaoka University of Technology, Kamitomioka, Nagaoka, Niigata 940-2188, Japan
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