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Baluchi A, Homaei A. Immobilization of l-asparaginase on chitosan nanoparticles for the purpose of long-term application. Int J Biol Macromol 2024; 257:128655. [PMID: 38065449 DOI: 10.1016/j.ijbiomac.2023.128655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 11/26/2023] [Accepted: 12/05/2023] [Indexed: 01/26/2024]
Abstract
Asparaginase holds significant commercial value as an enzyme in the food and pharmaceutical industries. This study examined the optimum and practical use of the l-asparaginase derived from Pseudomonas aeruginosa HR03. Specifically, the study focused on the effectiveness of the stabilized enzyme when applied to chitosan nanoparticles. The structure, size, and morphology of chitosan nanoparticles were evaluated in relation to the immobilization procedure. This assessment involved the use of several analytical techniques, including FT-IR, DLS, SEM, TEM, and EDS analysis. Subsequently, the durability of the enzyme that has been stabilized was assessed by evaluating its effectiveness under extreme temperatures of 60 and 70 °C, as well as at pH values of 3 and 12. The findings indicate that incorporating chitosan nanoparticles led to enhanced immobilization of the l-asparaginase enzyme. This improvement was observed in terms of long-term stability, stability under crucial temperature and pH conditions, as well as thermal stability. In addition, the optimum temperature increased from 40 to 50 °C, and the optimum pH increased from 8 to 9. Enzyme immobilization led to an increase in Km and a decrease in kcat compared to its free counterpart. Because of its enhanced long-term stability, l-asparaginase immobilization on chitosan nanoparticles may be a potential choice for use in industries that rely on l-asparaginase enzymes, particularly the pharmaceutical and food industries.
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Affiliation(s)
- Ayeshe Baluchi
- Department of Marine Biology, Faculty of Marine Science and Technology, University of Hormozgan, Bandarabbas, Iran
| | - Ahmad Homaei
- Department of Marine Biology, Faculty of Marine Science and Technology, University of Hormozgan, Bandarabbas, Iran.
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2
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Wear SS, Sande C, Ovchinnikova OG, Preston A, Whitfield C. Investigation of core machinery for biosynthesis of Vi antigen capsular polysaccharides in Gram-negative bacteria. J Biol Chem 2021; 298:101486. [PMID: 34896394 PMCID: PMC8760489 DOI: 10.1016/j.jbc.2021.101486] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 12/01/2021] [Accepted: 12/03/2021] [Indexed: 11/18/2022] Open
Abstract
Salmonella enterica serovar Typhi causes typhoid fever. It possesses a Vi antigen capsular polysaccharide coat that is important for virulence and is the basis of a current glycoconjugate vaccine. Vi antigen is also produced by environmental Bordetella isolates, while mammal-adapted Bordetella species (such as Bordetella bronchiseptica) produce a capsule of undetermined structure that cross-reacts with antibodies recognizing Vi antigen. The Vi antigen backbone is composed of poly-α-(1→4)-linked N-acetylgalactosaminuronic acid, modified with O-acetyl residues that are necessary for vaccine efficacy. Despite its biological and biotechnological importance, some central aspects of Vi antigen production are poorly understood. Here we demonstrate that TviE and TviD, two proteins encoded in the viaB (Vi antigen production) locus, interact and are the Vi antigen polymerase and O-acetyltransferase, respectively. Structural modeling and site-directed mutagenesis reveal that TviE is a GT4-family glycosyltransferase. While TviD has no identifiable homologs beyond Vi antigen systems in other bacteria, structural modeling suggests that it belongs to the large SGNH hydrolase family, which contains other O-acetyltransferases. Although TviD possesses an atypical catalytic triad, its O-acetyltransferase function was verified by antibody reactivity and 13C NMR data for tviD-mutant polysaccharide. The B. bronchiseptica genetic locus predicts a mode of synthesis distinct from classical S. enterica Vi antigen production, but which still involves TviD and TviE homologs that are both active in a reconstituted S. Typhi system. These findings provide new insight into Vi antigen production and foundational information for the glycoengineering of Vi antigen production in heterologous bacteria.
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Affiliation(s)
- Samantha S Wear
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Caitlin Sande
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Olga G Ovchinnikova
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Andrew Preston
- Milner Centre for Evolution and Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath, UK
| | - Chris Whitfield
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada.
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3
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Colin PY, Kintses B, Gielen F, Miton CM, Fischer G, Mohamed MF, Hyvönen M, Morgavi DP, Janssen DB, Hollfelder F. Ultrahigh-throughput discovery of promiscuous enzymes by picodroplet functional metagenomics. Nat Commun 2015; 6:10008. [PMID: 26639611 PMCID: PMC4686663 DOI: 10.1038/ncomms10008] [Citation(s) in RCA: 178] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 10/25/2015] [Indexed: 12/25/2022] Open
Abstract
Unculturable bacterial communities provide a rich source of biocatalysts, but their experimental discovery by functional metagenomics is difficult, because the odds are stacked against the experimentor. Here we demonstrate functional screening of a million-membered metagenomic library in microfluidic picolitre droplet compartments. Using bait substrates, new hydrolases for sulfate monoesters and phosphotriesters were identified, mostly based on promiscuous activities presumed not to be under selection pressure. Spanning three protein superfamilies, these break new ground in sequence space: promiscuity now connects enzymes with only distantly related sequences. Most hits could not have been predicted by sequence analysis, because the desired activities have never been ascribed to similar sequences, showing how this approach complements bioinformatic harvesting of metagenomic sequencing data. Functional screening of a library of unprecedented size with excellent assay sensitivity has been instrumental in identifying rare genes constituting catalytically versatile hubs in sequence space as potential starting points for the acquisition of new functions.
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Affiliation(s)
- Pierre-Yves Colin
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, UK
| | - Balint Kintses
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, UK
| | - Fabrice Gielen
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, UK
| | - Charlotte M Miton
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, UK
| | - Gerhard Fischer
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, UK
| | - Mark F Mohamed
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, UK
| | - Marko Hyvönen
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, UK
| | - Diego P Morgavi
- INRA, UMR1213 Herbivores, F-63122 Saint-Genès-Champanelle, France.,Clermont Université, VetAgro Sup, UMR Herbivores, BP 10448, F-63000 Clermont-Ferrand, France
| | - Dick B Janssen
- Groningen Biomolecular Science and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands
| | - Florian Hollfelder
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, UK
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Porter JL, Boon PLS, Murray TP, Huber T, Collyer CA, Ollis DL. Directed evolution of new and improved enzyme functions using an evolutionary intermediate and multidirectional search. ACS Chem Biol 2015; 10:611-21. [PMID: 25419863 DOI: 10.1021/cb500809f] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The ease with which enzymes can be adapted from their native roles and engineered to function specifically for industrial or commercial applications is crucial to enabling enzyme technology to advance beyond its current state. Directed evolution is a powerful tool for engineering enzymes with improved physical and catalytic properties and can be used to evolve enzymes where lack of structural information may thwart the use of rational design. In this study, we take the versatile and diverse α/β hydrolase fold framework, in the form of dienelactone hydrolase, and evolve it over three unique sequential evolutions with a total of 14 rounds of screening to generate a series of enzyme variants. The native enzyme has a low level of promiscuous activity toward p-nitrophenyl acetate but almost undetectable activity toward larger p-nitrophenyl esters. Using p-nitrophenyl acetate as an evolutionary intermediate, we have generated variants with altered specificity and catalytic activity up to 3 orders of magnitude higher than the native enzyme toward the larger nonphysiological p-nitrophenyl ester substrates. Several variants also possess increased stability resulting from the multidimensional approach to screening. Crystal structure analysis and substrate docking show how the enzyme active site changes over the course of the evolutions as either a direct or an indirect result of mutations.
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Affiliation(s)
- Joanne L. Porter
- Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Priscilla L. S. Boon
- Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Tracy P. Murray
- Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Thomas Huber
- Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Charles A. Collyer
- School
of Molecular Bioscience, University of Sydney, Sydney, New South Wales 2006, Australia
| | - David L. Ollis
- Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 2601, Australia
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Kumar A, Trefault N, Olaniran AO. Microbial degradation of 2,4-dichlorophenoxyacetic acid: Insight into the enzymes and catabolic genes involved, their regulation and biotechnological implications. Crit Rev Microbiol 2014; 42:194-208. [DOI: 10.3109/1040841x.2014.917068] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Kumar A, Pillay B, Olaniran AO. Two structurally different dienelactone hydrolases (TfdEI and TfdEII) from Cupriavidus necator JMP134 plasmid pJP4 catalyse cis- and trans-dienelactones with similar efficiency. PLoS One 2014; 9:e101801. [PMID: 25054964 PMCID: PMC4108320 DOI: 10.1371/journal.pone.0101801] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 06/10/2014] [Indexed: 11/18/2022] Open
Abstract
In this study, dienelactone hydrolases (TfdEI and TfdEII) located on plasmid pJP4 of Cupriavidus necator JMP134 were cloned, purified, characterized and three dimensional structures were predicted. tfdEI and tfdEII genes were cloned into pET21b vector and expressed in E. coli BL21(DE3). The enzymes were purified by applying ultra-membrane filtration, anion-exchange QFF and gel-filtration columns. The enzyme activity was determined by using cis-dienelactone. The three-dimensional structure of enzymes was predicted using SWISS-MODEL workspace and the biophysical properties were determined on ExPASy server. Both TfdEI and TfdEII (Mr 25 kDa) exhibited optimum activity at 37°C and pH 7.0. The enzymes retained approximately 50% of their activity after 1 h of incubation at 50°C and showed high stability against denaturing agents. The TfdEI and TfdEII hydrolysed cis-dienelactone at a rate of 0.258 and 0.182 µMs−1, with a Km value of 87 µM and 305 µM, respectively. Also, TfdEI and TfdEII hydrolysed trans-dienelactone at a rate of 0.053 µMs−1 and 0.0766 µMs−1, with a Km value of 84 µM and 178 µM, respectively. The TfdEI and TfdEII kcat/Km ratios were 0.12 µM−1s−1and 0.13 µM−1s−1 and 0.216 µM−1s−1 and 0.094 µM−1s−1 for for cis- and trans-dienelactone, respectively. The kcat/Km ratios for cis-dienelactone show that both enzymes catalyse the reaction with same efficiency even though Km value differs significantly. This is the first report to characterize and compare reaction kinetics of purified TfdEI and TfdEII from Cupriavidus necator JMP134 and may be helpful for further exploration of their catalytic mechanisms.
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Affiliation(s)
- Ajit Kumar
- Discipline of Microbiology, School of Life Sciences, College of Agriculture, Engineering and Science, University of KwaZulu-Natal (Westville Campus), Durban, Republic of South Africa
| | - Balakrishna Pillay
- Discipline of Microbiology, School of Life Sciences, College of Agriculture, Engineering and Science, University of KwaZulu-Natal (Westville Campus), Durban, Republic of South Africa
| | - Ademola O. Olaniran
- Discipline of Microbiology, School of Life Sciences, College of Agriculture, Engineering and Science, University of KwaZulu-Natal (Westville Campus), Durban, Republic of South Africa
- * E-mail:
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7
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Porter JL, Carr PD, Collyer CA, Ollis DL. Crystallization of dienelactone hydrolase in two space groups: structural changes caused by crystal packing. Acta Crystallogr F Struct Biol Commun 2014; 70:884-9. [PMID: 25005082 PMCID: PMC4089525 DOI: 10.1107/s2053230x1401108x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Accepted: 05/14/2014] [Indexed: 11/10/2022] Open
Abstract
Dienelactone hydrolase (DLH) is a monomeric protein with a simple α/β-hydrolase fold structure. It readily crystallizes in space group P2₁2₁2₁ from either a phosphate or ammonium sulfate precipitation buffer. Here, the structure of DLH at 1.85 Å resolution crystallized in space group C2 with two molecules in the asymmetric unit is reported. When crystallized in space group P2₁2₁2₁ DLH has either phosphates or sulfates bound to the protein in crucial locations, one of which is located in the active site, preventing substrate/inhibitor binding. Another is located on the surface of the enzyme coordinated by side chains from two different molecules. Crystallization in space group C2 from a sodium citrate buffer results in new crystallographic protein-protein interfaces. The protein backbone is highly similar, but new crystal contacts cause changes in side-chain orientations and in loop positioning. In regions not involved in crystal contacts, there is little change in backbone or side-chain configuration. The flexibility of surface loops and the adaptability of side chains are important factors enabling DLH to adapt and form different crystal lattices.
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Affiliation(s)
- Joanne L. Porter
- Research School of Chemistry, Australian National University, Building 137, Sullivans Creek Road, Canberra, ACT 0200, Australia
| | - Paul D. Carr
- Research School of Chemistry, Australian National University, Building 137, Sullivans Creek Road, Canberra, ACT 0200, Australia
| | - Charles A. Collyer
- School of Molecular Bioscience, University of Sydney, Biochemistry Building, Sydney, NSW 2006, Australia
| | - David L. Ollis
- Research School of Chemistry, Australian National University, Building 137, Sullivans Creek Road, Canberra, ACT 0200, Australia
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8
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Liao C, Peng Y, Ma W, Liu R, Li C, Li X. Proteomic analysis revealed nitrogen-mediated metabolic, developmental, and hormonal regulation of maize (Zea mays L.) ear growth. J Exp Bot 2012; 63:5275-88. [PMID: 22936831 PMCID: PMC3430998 DOI: 10.1093/jxb/ers187] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Optimal nitrogen (N) supply is critical for achieving high grain yield of maize. It is well established that N deficiency significantly reduces grain yield and N oversupply reduces N use efficiency without significant yield increase. However, the underlying proteomic mechanism remains poorly understood. The present field study showed that N deficiency significantly reduced ear size and dry matter accumulation in the cob and grain, directly resulting in a significant decrease in grain yield. The N content, biomass accumulation, and proteomic variations were further analysed in young ears at the silking stage under different N regimes. N deficiency significantly reduced N content and biomass accumulation in young ears of maize plants. Proteomic analysis identified 47 proteins with significant differential accumulation in young ears under different N treatments. Eighteen proteins also responded to other abiotic and biotic stresses, suggesting that N nutritional imbalance triggered a general stress response. Importantly, 24 proteins are involved in regulation of hormonal metabolism and functions, ear development, and C/N metabolism in young ears, indicating profound impacts of N nutrition on ear growth and grain yield at the proteomic level.
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Affiliation(s)
- Chengsong Liao
- Department of Plant Nutrition, China Agricultural University, Beijing, 100193, China
| | - Yunfeng Peng
- Department of Plant Nutrition, China Agricultural University, Beijing, 100193, China
| | - Wei Ma
- Department of Plant Nutrition, China Agricultural University, Beijing, 100193, China
| | - Renyi Liu
- Department of Botany and Plant Sciences, University of California, Riverside, CA 92521, USA
| | - Chunjian Li
- Department of Plant Nutrition, China Agricultural University, Beijing, 100193, China
| | - Xuexian Li
- Department of Plant Nutrition, China Agricultural University, Beijing, 100193, China
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Walker I, Hennessy JE, Ollis DL, Easton CJ. Substrate-induced conformational change and isomerase activity of dienelactone hydrolase and its site-specific mutants. Chembiochem 2012; 13:1645-51. [PMID: 22761053 DOI: 10.1002/cbic.201200232] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Indexed: 11/06/2022]
Abstract
Studies of the interactions of dienelactone hydrolase (DLH) and its mutants with both E and Z dienelactone substrates show that the enzyme exhibits two different conformational responses specific for hydrolysis of each of its substrate isomers. DLH facilitates hydrolysis of the Z dienelactone through an unusual charge-relay system that is initiated by interaction between the substrate carboxylate and an enzyme arginine residue that activates an otherwise non-nucleophilic cysteine. The E dienelactone does not display this substrate-arginine binding interaction, but instead induces an alternate conformational response that promotes hydrolysis. Furthermore, the substitution of cysteine 123 for serine (C123S) in DLH, instead of inactivating the enzyme as is typical for this active-site mutation, changes the catalysis from substrate hydrolysis to isomerisation. This is due to the deacylation of the acyl-enzyme intermediates being much slower, thereby increasing their lifetimes and allowing for their interconversion through isomerisation, followed by relactonisation.
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Affiliation(s)
- Ian Walker
- Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia
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Bains J, Kaufman L, Farnell B, Boulanger MJ. A product analog bound form of 3-oxoadipate-enol-lactonase (PcaD) reveals a multifunctional role for the divergent cap domain. J Mol Biol 2011; 406:649-58. [PMID: 21237173 DOI: 10.1016/j.jmb.2011.01.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2010] [Revised: 12/24/2010] [Accepted: 01/03/2011] [Indexed: 11/15/2022]
Abstract
Lactones are a class of structurally diverse molecules that serve essential roles in biological processes ranging from quorum sensing to the aerobic catabolism of aromatic compounds. Not surprisingly, enzymes involved in the bioprocessing of lactones are often targeted for protein engineering studies with the potential, for example, of optimized bioremediation of aromatic pollutants. The enol-lactone hydrolase (ELH) represents one such class of targeted enzymes and catalyzes the conversion of 3-oxoadipate-enol-lactone into the linear β-ketoadipate. To define the structural details that govern ELH catalysis and assess the impact of divergent features predicted by sequence analysis, we report the first structural characterization of an ELH (PcaD) from Burkholderia xenovorans LB400 in complex with the product analog levulinic acid. The overall dimeric structure of PcaD reveals an α-helical cap domain positioned atop a core α/β-hydrolase domain. Despite the localization of the conserved catalytic triad to the core domain, levulinic acid is bound largely within the region of the active site defined by the cap domain, suggesting a key role for this divergent substructure in mediating product release. Furthermore, the architecture of the cap domain results in an unusually deep active-site pocket with topological features to restrict binding to small or kinked substrates. The evolutionary basis for this substrate selectivity is discussed with respect to the homologous dienelactone hydrolase. Overall, the PcaD costructure provides a detailed insight into the intimate role of the cap domain in influencing all aspects of substrate binding, turnover, and product release.
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Affiliation(s)
- Jasleen Bains
- Department of Biochemistry and Microbiology, University of Victoria, PO Box 3055 STN CSC, Victoria, BC, Canada
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Cámara B, Nikodem P, Bielecki P, Bobadilla R, Junca H, Pieper DH. Characterization of a gene cluster involved in 4-chlorocatechol degradation by Pseudomonas reinekei MT1. J Bacteriol 2009; 191:4905-15. [PMID: 19465655 DOI: 10.1128/JB.00331-09] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas reinekei MT1 has previously been reported to degrade 4- and 5-chlorosalicylate by a pathway with 4-chlorocatechol, 3-chloromuconate, 4-chloromuconolactone, and maleylacetate as intermediates, and a gene cluster channeling various salicylates into an intradiol cleavage route has been reported. We now report that during growth on 5-chlorosalicylate, besides a novel (chloro)catechol 1,2-dioxygenase, C12O(ccaA), a novel (chloro)muconate cycloisomerase, MCI(ccaB), which showed features not yet reported, was induced. This cycloisomerase, which was practically inactive with muconate, evolved for the turnover of 3-substituted muconates and transforms 3-chloromuconate into equal amounts of cis-dienelactone and protoanemonin, suggesting that it is a functional intermediate between chloromuconate cycloisomerases and muconate cycloisomerases. The corresponding genes, ccaA (C12O(ccaA)) and ccaB (MCI(ccaB)), were located in a 5.1-kb genomic region clustered with genes encoding trans-dienelactone hydrolase (ccaC) and maleylacetate reductase (ccaD) and a putative regulatory gene, ccaR, homologous to regulators of the IclR-type family. Thus, this region includes genes sufficient to enable MT1 to transform 4-chlorocatechol to 3-oxoadipate. Phylogenetic analysis showed that C12O(ccaA) and MCI(ccaB) are only distantly related to previously described catechol 1,2-dioxygenases and muconate cycloisomerases. Kinetic analysis indicated that MCI(ccaB) and the previously identified C12O(salD), rather than C12O(ccaA), are crucial for 5-chlorosalicylate degradation. Thus, MT1 uses enzymes encoded by a completely novel gene cluster for degradation of chlorosalicylates, which, together with a gene cluster encoding enzymes for channeling salicylates into the ortho-cleavage pathway, form an effective pathway for 4- and 5-chlorosalicylate mineralization.
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Cámara B, Marín M, Schlömann M, Hecht H, Junca H, Pieper DH. trans-Dienelactone hydrolase from Pseudomonas reinekei MT1, a novel zinc-dependent hydrolase. Biochem Biophys Res Commun 2008; 376:423-8. [DOI: 10.1016/j.bbrc.2008.09.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2008] [Accepted: 09/03/2008] [Indexed: 11/24/2022]
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Yano H, Kuroda S. Introduction of the Disulfide Proteome: Application of a Technique for the Analysis of Plant Storage Proteins as Well as Allergens. J Proteome Res 2008; 7:3071-9. [DOI: 10.1021/pr8003453] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Hiroyuki Yano
- National Institute of Crop Science, Tsukuba 305-8518, Japan, and BRAIN Tokyo Office, Minato-ku, Tokyo 105-0001, Japan
| | - Shigeru Kuroda
- National Institute of Crop Science, Tsukuba 305-8518, Japan, and BRAIN Tokyo Office, Minato-ku, Tokyo 105-0001, Japan
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Affiliation(s)
- Philip A Rea
- Plant Science Institute, Department of Biology, University of Pennsylvania, 3800 Hamilton Walk, Philadelphia, PA 19104-6018, USA.
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Rea PA, Vatamaniuk OK, Rigden DJ. Weeds, worms, and more. Papain's long-lost cousin, phytochelatin synthase. Plant Physiol 2004; 136:2463-74. [PMID: 15375203 PMCID: PMC523314 DOI: 10.1104/pp.104.048579] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2004] [Revised: 07/15/2004] [Accepted: 07/18/2004] [Indexed: 05/18/2023]
Affiliation(s)
- Philip A Rea
- Plant Science Institute, Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA.
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Vatamaniuk OK, Mari S, Lang A, Chalasani S, Demkiv LO, Rea PA. Phytochelatin Synthase, a Dipeptidyltransferase That Undergoes Multisite Acylation with γ-Glutamylcysteine during Catalysis. J Biol Chem 2004; 279:22449-60. [PMID: 15004013 DOI: 10.1074/jbc.m313142200] [Citation(s) in RCA: 118] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Phytochelatin (PC) synthase has been assumed to be a gamma-glutamylcysteine dipeptidyl transpeptidase (EC 2.3.2.15) and, more recently, as exemplified by analyses of the immunopurified recombinant enzyme from Arabidopsis thaliana (AtPCS1-FLAG), has been shown to catalyze a PC synthetic reaction with kinetics that approximates a bisubstrate-substituted enzyme mechanism in which millimolar concentrations of free GSH and micromolar concentrations of heavy metal.GSH thiolates (e.g. cadmium.GS(2)) or millimolar concentrations of S-alkylglutathiones serve as cosubstrates. Here, we show, by direct analyses of the stoichiometry of AtPCS1-FLAG-catalyzed PC synthesis, the kinetics and stoichiometry of acylation of the enzyme and release of free glycine from gamma-Glu-Cys donors, and the effects of the Cys-to-Ser or -Ala and Ser-to-Ala substitution of conserved residues in the catalytic N-terminal half of the enzyme, that PC synthase is indeed a dipeptidyltransferase that undergoes gamma-Glu-Cys acylation at two sites during catalysis, one of which, in accord with a cysteine protease model, likely corresponds to or is at least tightly coupled with Cys(56). The identity of the second site of enzyme modification remains to be determined, but it is distinguishable from the first Cys(56)-dependent site, which is amenable to gamma-Glu-Cys acylation by free GSH, because its acylation not only depends on the provision of Cd(2+) or GSH with a blocked, S-alkylated thiol group, but is also necessary for net PC synthesis. We conclude that des-Gly-PCs are not generated as an immediate by-product, but rather that the enzyme catalyzes a dipeptidyl transfer reaction in which some of the energy liberated upon cleavage of the Cys-Gly bonds of the gamma-Glu-Cys donors in the first phase of the catalytic cycle is conserved through the formation of a two site-substituted gamma-Glu-Cys acyl-enzyme intermediate whose hydrolysis provides the energy required for the formation of the new peptide bond required for the extension of PC chain length by one gamma-Glu-Cys repeat per catalytic cycle.
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Affiliation(s)
- Olena K Vatamaniuk
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6018, USA
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17
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Abstract
Chlorophenols belong to the group of toxic and persistent to microbial attack xenobiotics. Nevertheless, due to the adaptation microorganisms acquire the ability to use chlorophenols as the sole source of carbon and energy. The present review describes the diversity of aerobic pathways for the utilization of halogenated phenols by bacteria with the emphasis on the main reactions and intermediates formed, enzymes responsible for these reactions and their genetic basis. Taking into account (i) the fact that enzymes degrading chlorophenols are similar to the ones involved in the conversion of other (chloro)aromatic compounds and (ii) that present numerous publications describing the properties of separated enzymes or encoding their genes are published, this review was planned as the attempt to present both, the most general and specific aspects in chlorophenols degradation with the emphasis on the literature of the last ten years.
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Affiliation(s)
- Inna P Solyanikova
- G. K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
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18
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Vatamaniuk OK, Mari S, Lu YP, Rea PA. Mechanism of heavy metal ion activation of phytochelatin (PC) synthase: blocked thiols are sufficient for PC synthase-catalyzed transpeptidation of glutathione and related thiol peptides. J Biol Chem 2000; 275:31451-9. [PMID: 10807919 DOI: 10.1074/jbc.m002997200] [Citation(s) in RCA: 212] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The dependence of phytochelatin synthase (gamma-glutamylcysteine dipeptidyltranspeptidase (PCS), EC ) on heavy metals for activity has invariably been interpreted in terms of direct metal binding to the enzyme. Here we show, through analyses of immunopurified, recombinant PCS1 from Arabidopsis thaliana (AtPCS1), that free metal ions are not essential for catalysis. Although AtPCS1 appears to be primarily activated posttranslationally in the intact plant and purified AtPCS1 is able to bind heavy metals directly, metal binding per se is not responsible for catalytic activation. As exemplified by Cd(2+)- and Zn(2+)-dependent AtPCS1-mediated catalysis, the kinetics of PC synthesis approximate a substituted enzyme mechanism in which micromolar heavy metal glutathione thiolate (e.g. Cd.GS(2) or Zn.GS(2)) and free glutathione act as gamma-Glu-Cys acceptor and donor. Further, as demonstrated by the facility of AtPCS1 for the net synthesis of S-alkyl-PCs from S-alkylglutathiones with biphasic kinetics, consistent with the sufficiency of S-alkylglutathiones as both gamma-Glu-Cys donors and acceptors in media devoid of metals, even heavy metal thiolates are dispensable. It is concluded that the dependence of AtPCS1 on the provision of heavy metal ions for activity in media containing glutathione and other thiol peptides is a reflection of this enzyme's requirement for glutathione-like peptides containing blocked thiol groups for activity.
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Affiliation(s)
- O K Vatamaniuk
- Department of Biology, Plant Science Institute, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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Fischer F, Künne S, Fetzner S. Bacterial 2,4-dioxygenases: new members of the alpha/beta hydrolase-fold superfamily of enzymes functionally related to serine hydrolases. J Bacteriol 1999; 181:5725-33. [PMID: 10482514 PMCID: PMC94093 DOI: 10.1128/jb.181.18.5725-5733.1999] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
1H-3-hydroxy-4-oxoquinoline 2,4-dioxygenase (Qdo) from Pseudomonas putida 33/1 and 1H-3-hydroxy-4-oxoquinaldine 2,4-dioxygenase (Hod) from Arthrobacter ilicis Rü61a catalyze an N-heterocyclic-ring cleavage reaction, generating N-formylanthranilate and N-acetylanthranilate, respectively, and carbon monoxide. Amino acid sequence comparisons between Qdo, Hod, and a number of proteins belonging to the alpha/beta hydrolase-fold superfamily of enzymes and analysis of the similarity between the predicted secondary structures of the 2,4-dioxygenases and the known secondary structure of haloalkane dehalogenase from Xanthobacter autotrophicus GJ10 strongly suggested that Qdo and Hod are structurally related to the alpha/beta hydrolase-fold enzymes. The residues S95 and H244 of Qdo were found to be arranged like the catalytic nucleophilic residue and the catalytic histidine, respectively, of the alpha/beta hydrolase-fold enzymes. Investigation of the potential functional significance of these and other residues of Qdo through site-directed mutagenesis supported the hypothesis that Qdo is structurally as well as functionally related to serine hydrolases, with S95 being a possible catalytic nucleophile and H244 being a possible catalytic base. A hypothetical reaction mechanism for Qdo-catalyzed 2,4-dioxygenolysis, involving formation of an ester bond between the catalytic serine residue and the carbonyl carbon of the substrate and subsequent dioxygenolysis of the covalently bound anionic intermediate, is discussed.
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Affiliation(s)
- F Fischer
- Mikrobiologie, Fachbereich 7, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany
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20
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Abstract
The structures of cofactor-free haloperoxidases from Streptomyces aureofaciens, Streptomyces lividans, and Pseudomonas fluorescens have been determined at resolutions between 1.9 A and 1.5 A. The structures of two enzymes complexed with benzoate or propionate identify the binding site for the organic acids which are required for the haloperoxidase activity. Based on these complexes and on the structure of an inactive variant, a reaction mechanism is proposed for the halogenation reaction with peroxoacid and hypohalous acid as reaction intermediates. Comparison of the structures suggests that a specific halide binding site is absent in the enzymes but that hydrophobic organic compounds may fit into the active site pocket for halogenation at preferential sites.
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Affiliation(s)
- B Hofmann
- Department SF, GBF (Gesellschaft für Biotechnologische Forschung), Mascheroder Weg 1, Braunschweig, D-38124, FRG
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21
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Abstract
Protoanemonin is a toxic metabolite which may be formed during the degradation of some chloroaromatic compounds, such as polychlorinated biphenyls, by natural microbial consortia. We show here that protoanemonin can be transformed by dienelactone hydrolase of Pseudomonas sp. strain B13 to cis-acetylacrylate. Although similar Km values were observed for cis-dienelactone and protoanemonin, the turnover rate of protoanemonin was only 1% that of cis-dienelactone. This indicates that at least this percentage of the enzyme is in the active state, even in the absence of activation. The trans-dienelactone hydrolase of Pseudomonas sp. strain RW10 did not detectably transform protoanemonin. Obviously, Pseudomonas sp. strain B13 possesses at least two mechanisms to avoid protoanemonin toxicity, namely a highly active chloromuconate cycloisomerase, which routes most of the 3-chloro-cis,cis-muconate to the cis-dienelactone, thereby largely preventing protoanemonin formation, and dienelactone hydrolase, which detoxifies any small amount of protoanemonin that might nevertheless be formed.
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Affiliation(s)
- M Brückmann
- Department of Microbiology, National Research Centre for Biotechnology, Braunschweig, Germany
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Krooshof GH, Kwant EM, Damborský J, Koca J, Janssen DB. Repositioning the catalytic triad aspartic acid of haloalkane dehalogenase: effects on stability, kinetics, and structure. Biochemistry 1997; 36:9571-80. [PMID: 9236003 DOI: 10.1021/bi971014t] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Haloalkane dehalogenase (DhlA) catalyzes the hydrolysis of haloalkanes via an alkyl-enzyme intermediate. The covalent intermediate, which is formed by nucleophilic substitution with Asp124, is hydrolyzed by a water molecule that is activated by His289. The role of Asp260, which is the third member of the catalytic triad, was studied by site-directed mutagenesis. Mutation of Asp260 to asparagine resulted in a catalytically inactive D260N mutant, which demonstrates that the triad acid Asp260 is essential for dehalogenase activity. Furthermore, Asp260 has an important structural role, since the D260N enzyme accumulated mainly in inclusion bodies during expression, and neither substrate nor product could bind in the active-site cavity. Activity for brominated substrates was restored to D260N by replacing Asn148 with an aspartic or glutamic acid. Both double mutants D260N+N148D and D260N+N148E had a 10-fold reduced kcat and 40-fold higher Km values for 1,2-dibromoethane compared to the wild-type enzyme. Pre-steady-state kinetic analysis of the D260N+N148E double mutant showed that the decrease in kcat was mainly caused by a 220-fold reduction of the rate of carbon-bromine bond cleavage and a 10-fold decrease in the rate of hydrolysis of the alkyl-enzyme intermediate. On the other hand, bromide was released 12-fold faster and via a different pathway than in the wild-type enzyme. Molecular modeling of the mutant showed that Glu148 indeed could take over the interaction with His289 and that there was a change in charge distribution in the tunnel region that connects the active site with the solvent. On the basis of primary structure similarity between DhlA and other alpha/beta-hydrolase fold dehalogenases, we propose that a conserved acidic residue at the equivalent position of Asn148 in DhlA is the third catalytic triad residue in the latter enzymes.
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Affiliation(s)
- G H Krooshof
- Department of Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
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Fritsche E, Humm A, Huber R. Substrate binding and catalysis by L-arginine:glycine amidinotransferase--a mutagenesis and crystallographic study. Eur J Biochem 1997; 247:483-90. [PMID: 9266688 DOI: 10.1111/j.1432-1033.1997.00483.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
L-Arginine:glycine amidinotransferase catalyzes the committed step in the biosynthesis of creatine. Eight active-site mutants, D170N, D254N, H303V, D305A, R322E, S355A, C407S, and C410A of recombinant human L-arginine:glycine amidinotransferase were prepared by site-directed mutagenesis and enzymatically characterized. The crystal structures of the three mutants D170N, D254N, and C407S have been determined at 0.28-nm, 0.29-nm and 0.236-nm resolution, respectively. The mutation of active-site residues which are involved in substrate-binding yielded inactive mutants. Substitution of Asp254, which is not directly involved in substrate binding but is thought to transfer protons in concert with the His303 imidazole group, results in a strongly (2000-fold) reduced activity. However, the substitution of Cys410, a residue near the active site but not involved in catalysis or substrate binding, by Ala does not change the kinetic properties with respect to the wild-type enzyme. The loss of enzymatic activity of the D170N, D254N, C407S and likely all other mutants is solely due to the inserted point mutations, affecting substrate binding or transition-state stabilization, and not due to major conformational rearrangements of the protein. These results show that a His-Asp pair on one side of the substrate and a Cys on the other side are key residues for activity and are part of a disjoint triad. The imidazole ring of the His is proposed to act as a general acid/general base during catalysis whereas the Cys acts as a nucleophile analogous to Cys25 of papain-like cysteine proteinases.
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Affiliation(s)
- E Fritsche
- Max-Planck-Institut für Biochemie, Martinsried, Germany
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Beveridge AJ. A theoretical study of the active sites of papain and S195C rat trypsin: implications for the low reactivity of mutant serine proteinases. Protein Sci 1996; 5:1355-65. [PMID: 8819168 PMCID: PMC2143470 DOI: 10.1002/pro.5560050714] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The serine and cysteine proteinases represent two important classes of enzymes that use a catalytic triad to hydrolyze peptides and esters. The active site of the serine proteinases consists of three key residues, Asp...His...Ser. The hydroxyl group of serine functions as a nucleophile and the imidazole ring of histidine functions as a general acid/general base during catalysis. Similarly, the active site of the cysteine proteinases also involves three key residues: Asn, His, and Cys. The active site of the cysteine proteinases is generally believed to exist as a zwitterion (Asn...His+...Cys-) with the thiolate anion of the cysteine functioning as a nucleophile during the initial stages of catalysis. Curiously, the mutant serine proteinases, thiol subtilisin and thiol trypsin, which have the hybrid Asp...His...Cys triad, are almost catalytically inert. In this study, ab initio Hartree-Fock calculations have been performed on the active sites of papain and the mutant serine proteinase S195C rat trypsin. These calculations predict that the active site of papain exists predominately as a zwitterion (Cys-...His+...Asn). However, similar calculations on S195C rat trypsin demonstrate that the thiol mutant is unable to form a reactive thiolate anion prior to catalysis. Furthermore, structural comparisons between native papain and S195C rat trypsin have demonstrated that the spatial juxtapositions of the triad residues have been inverted in the serine and cysteine proteinases and, on this basis, I argue that it is impossible to convert a serine proteinase to a cysteine proteinase by site-directed mutagenesis.
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Affiliation(s)
- A J Beveridge
- Daresbury Laboratory, Warrington, Cheshire, United Kingdom.
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25
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Abstract
The aerobic bacterial degradation of chloroaromatic compounds often involves chlorosubstituted catechols as central intermediates. They are converted to 3-oxoadipate in a series of reactions similar to that for catechol catabolism and therefore designated as modified ortho-cleavage pathway. Among the enzymes of this catabolic route, the chlorocatechol 1,2-dioxygenases are known to have a relaxed substrate specificity. In contrast, several chloromuconate cycloisomerases are more specific, and the dienelactone hydrolases of chlorocatechol catabolic pathways do not even convert the corresponding intermediate of catechol degradation, 3-oxoadipate enol-lactone. While the sequences of chlorocatechol 1,2-dioxygenases and chloromuconate cycloisomerases are very similar to those of catechol 1,2-dioxygenases and muconate cycloisomerases, respectively, the relationship between dienelactone hydrolases and 3-oxoadipate enol-lactone hydrolases is more distant. They seem to share an alpha/beta hydrolase fold, but the sequences comprising the fold are quite dissimilar. Therefore, for chlorocatechol catabolism, dienelactone hydrolases might have been recruited from some other, preexisting pathway. Their relationship to dienelactone (hydrolases identified in 4-fluorobenzoate utilizing strains of Alcaligenes and Burkholderia (Pseudomonas) cepacia is investigated). Sequence evidence suggests that the chlorocatechol catabolic operons of the plasmids pJP4, pAC27, and pP51 have been derived from a common precursor. The latter seems to have evolved for the purpose of halocatechol catabolism, and may be considerably older than the chemical industry.
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Affiliation(s)
- M Schlömann
- Institut für Mikrobiologie, Universität Stuttgart, Germany
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Boehlein SK, Richards NG, Walworth ES, Schuster SM. Arginine 30 and asparagine 74 have functional roles in the glutamine dependent activities of Escherichia coli asparagine synthetase B. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(18)47088-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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