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Comparative Analysis of the Conversion of Mandelonitrile and 2-Phenylpropionitrile by a Large Set of Variants Generated from a Nitrilase Originating from Pseudomonas fluorescens EBC191. Molecules 2019; 24:molecules24234232. [PMID: 31766372 PMCID: PMC6930498 DOI: 10.3390/molecules24234232] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 11/15/2019] [Accepted: 11/18/2019] [Indexed: 11/17/2022] Open
Abstract
The arylacetonitrilase from the bacterium Pseudomonas fluorescens EBC191 has been intensively studied as a model to understand the molecular basis for the substrate-, reaction-, and enantioselectivity of nitrilases. The nitrilase converts various aromatic and aliphatic nitriles to the corresponding acids and varying amounts of the corresponding amides. The enzyme has been analysed by site-specific mutagenesis and more than 50 different variants have been generated and analysed for the conversion of (R,S)-mandelonitrile and (R,S)-2-phenylpropionitrile. These comparative analyses demonstrated that single point mutations are sufficient to generate enzyme variants which hydrolyse (R,S)-mandelonitrile to (R)-mandelic acid with an enantiomeric excess (ee) of 91% or to (S)-mandelic acid with an ee-value of 47%. The conversion of (R,S)-2-phenylpropionitrile by different nitrilase variants resulted in the formation of either (S)- or (R)-2-phenylpropionic acid with ee-values up to about 80%. Furthermore, the amounts of amides that are produced from (R,S)-mandelonitrile and (R,S)-2-phenylpropionitrile could be changed by single point mutations between 2%–94% and <0.2%–73%, respectively. The present study attempted to collect and compare the results obtained during our previous work, and to obtain additional general information about the relationship of the amide forming capacity of nitrilases and the enantiomeric composition of the products.
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Thakur N, Sharma NK, Thakur S, Monika, Bhalla TC. Bioprocess Development for the Synthesis of 4-Aminophenylacetic Acid Using Nitrilase Activity of Whole Cells of Alcaligenes faecalis MTCC 12629. Catal Letters 2019. [DOI: 10.1007/s10562-019-02762-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Conversion of aliphatic nitriles by the arylacetonitrilase from Pseudomonas fluorescens EBC191. World J Microbiol Biotechnol 2018; 34:91. [PMID: 29896645 DOI: 10.1007/s11274-018-2477-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 06/08/2018] [Indexed: 10/14/2022]
Abstract
The conversion of aliphatic nitriles by the arylacetonitrilase from Pseudomonas fluorescens EBC191 (NitA) was analyzed. The nitrilase hydrolysed a wide range of aliphatic mono- and dinitriles and showed a preference for unsaturated aliphatic substrates containing 5-6 carbon atoms. In addition, increased reaction rates were also found for aliphatic nitriles carrying electron withdrawing substituents (e.g. chloro- or hydroxy-groups) close to the nitrile group. Aliphatic dinitriles were attacked only at one of the nitrile groups and with most of the tested dinitriles the monocarboxylates were detected as major products. In contrast, fumarodinitrile was converted to the monocarboxylate and the monocarboxamide in a ratio of about 65:35. Significantly different relative amounts of the two products were observed with two nitrilase variants with altered reaction specifities. NitA converted some aliphatic substrates with higher rates than 2-phenylpropionitrile, which is one of the standard substrates for arylacetonitrilases. This indicated that the traditional classification of nitrilases as "arylacetonitrilases", "aromatic" or "aliphatic" nitrilases might require some corrections. This was also suggested by the construction of some variants of NitA which were modified in an amino acid residue which was previously suggested to be essential for the conversion of aliphatic substrates by a homologous nitrilase.
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Xue YP, Jiao B, Hua DE, Cheng F, Liu ZQ, Zheng YG. Improving catalytic performance of an arylacetonitrilase by semirational engineering. Bioprocess Biosyst Eng 2017; 40:1565-1572. [DOI: 10.1007/s00449-017-1812-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Accepted: 07/01/2017] [Indexed: 01/08/2023]
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Ammonium acrylate biomanufacturing by an engineered Rhodococcus ruber with nitrilase overexpression and double-knockout of nitrile hydratase and amidase. ACTA ACUST UNITED AC 2016; 43:1631-1639. [DOI: 10.1007/s10295-016-1840-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Accepted: 09/23/2016] [Indexed: 01/04/2023]
Abstract
Abstract
Rhodococcus ruber TH was selected as a parent strain to engineer for biomanufacturing of ammonium acrylate; the characteristics of this strain included accelerated growth rate, high cell tolerance and natively overexpressed nitrile hydratase (NHase). Transcriptome analysis revealed that the transcription levels of the native NHase, amidase and nitrilase were extremely high, moderate and extremely low, respectively. Through NHase-amidase double-knockout and amidase single-knockout, the engineered strains R. ruber THdAdN and R. ruber THdA were obtained for overexpression of a heterologous nitrilase from R. rhodochrous tg1-A6 using a urea-induced Pa2 promoter. The nitrilase activity toward substrate acrylonitrile in the engineered THdAdN(Nit) reached 187.0 U/mL at 42 h, threefold of that R. rhodochrous tg1-A6 and 2.3-fold of that of THdA(Nit). The optimal catalysis temperature and pH of the nitrilases in different cells exhibited no significant difference. Using the cells as catalysts, biomanufacturing of ammonium acrylate was performed under room temperature. When catalyzed by the engineered THdAdN(Nit), the titer and productivity of ammonium acrylate dramatically increased to 741.0 g/L and 344.9 g/L/h, which are the highest results reported to date.
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Xue YP, Shi CC, Xu Z, Jiao B, Liu ZQ, Huang JF, Zheng YG, Shen YC. Design of Nitrilases with Superior Activity and Enantioselectivity towards Sterically Hindered Nitrile by Protein Engineering. Adv Synth Catal 2015. [DOI: 10.1002/adsc.201500039] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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van Rantwijk F, Stolz A. Enzymatic cascade synthesis of (S)-2-hydroxycarboxylic amides and acids: Cascade reactions employing a hydroxynitrile lyase, nitrile-converting enzymes and an amidase. ACTA ACUST UNITED AC 2015. [DOI: 10.1016/j.molcatb.2014.08.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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9
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Sosedov O, Stolz A. Improvement of the amides forming capacity of the arylacetonitrilase from Pseudomonas fluorescens EBC191 by site-directed mutagenesis. Appl Microbiol Biotechnol 2014; 99:2623-35. [DOI: 10.1007/s00253-014-6061-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Revised: 08/26/2014] [Accepted: 08/29/2014] [Indexed: 10/24/2022]
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10
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Large α-aminonitrilase activity screening of nitrilase superfamily members: Access to conversion and enantiospecificity by LC–MS. ACTA ACUST UNITED AC 2014. [DOI: 10.1016/j.molcatb.2014.05.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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11
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Liu ZQ, Zhang XH, Xue YP, Xu M, Zheng YG. Improvement of Alcaligenes faecalis nitrilase by gene site saturation mutagenesis and its application in stereospecific biosynthesis of (R)-(-)-mandelic acid. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2014; 62:4685-4694. [PMID: 24766313 DOI: 10.1021/jf405683f] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Nitrilases have recently received considerable attention as the biocatalysts for stereospecific production of carboxylic acids. To improve the activity, the nitrilase from Alcaligenes faecalis was selected for further modification by the gene site saturation mutagenesis method (GSSM), based on homology modeling and previous reports about mutations. After mutagenesis, the positive mutants were selected using a convenient two-step high-throughput screening method based on product formation and pH indicator combined with the HPLC method. After three rounds of GSSM, Mut3 (Gln196Ser/Ala284Ile) with the highest activity and ability of tolerance to the substrate was selected. As compared to the wild-type A. faecalis nitrilase, Mut3 showed 154% higher specific activity. Mut3 could retain 91.6% of its residual activity after incubation at pH 6.5 for 6 h. In a fed-batch reaction with 800 mM mandelonitrile as the substrate, the cumulative production of (R)-(-)-mandelic acid after 7.5 h of conversion reached 693 mM with an enantiomeric excess of 99%, and the space-time productivity of Mut3 was 21.50-fold higher than that of wild-type nitrilase. The Km, Vmax, and k(cat) of wild-type and Mut3 for mandelonitrile were 20.64 mM, 33.74 μmol mg(-1) min(-1), 24.45 s(-1), and 9.24 mM, 47.68 μmol mg(-1) min(-1), and 34.55 s(-1), respectively. A homology modeling and molecular docking study showed that the diameter of the catalytic tunnel of Mut3 became longer and that the tunnel volume was smaller. These structural changes are proposed to improve the hydrolytic activity and pH stability of Mut3. Mut3 has the potential for industrial applications in the upscale production of (R)-(-)-mandelic acid.
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Affiliation(s)
- Zhi-Qiang Liu
- Institute of Bioengineering, Zhejiang University of Technology , Hangzhou, Zhejiang 310014, People's Republic of China
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Cloning, overexpression, and characterization of a high enantioselective nitrilase from Sphingomonas wittichii RW1 for asymmetric synthesis of (R)-phenylglycine. Appl Biochem Biotechnol 2014; 173:365-77. [PMID: 24664232 DOI: 10.1007/s12010-014-0845-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2013] [Accepted: 03/02/2014] [Indexed: 10/25/2022]
Abstract
In this study, a high (R)-enantioselective nitrilase gene from Sphingomonas wittichii RW1 was cloned and overexpressed in Escherichia coli BL21 (DE3). The recombinant nitrilase was purified to homogeneity with a molecular weight of 40 kDa. The pH and temperature optima were shown to be pH 8.0 and 40 °C, respectively. The purified nitrilase was most active toward succinonitrile, approximately 30-fold higher than that for phenylglycinonitrile. Using the E. coli BL21/ReSWRW1 whole cells as biocatalysts, the kinetic resolution for asymmetric synthesis of (R)-phenylglycine was investigated at pH 6.0. A yield of 46 % was obtained with 95 % enantiomeric excess (ee), which made it a promising biocatalyst for synthesis of (R)-phenylglycine.
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Wang H, Sun H, Gao W, Wei D. Efficient Production of (R)-o-Chloromandelic Acid by Recombinant Escherichia coli Cells Harboring Nitrilase from Burkholderia cenocepacia J2315. Org Process Res Dev 2013. [DOI: 10.1021/op400174a] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Hualei Wang
- State Key Laboratory of Bioreactor Engineering, New World Institute of Biotechnology, East China University of Science and Technology, Shanghai 200237, People’s Republic of China
| | - Huihui Sun
- State Key Laboratory of Bioreactor Engineering, New World Institute of Biotechnology, East China University of Science and Technology, Shanghai 200237, People’s Republic of China
| | - Wenyuan Gao
- State Key Laboratory of Bioreactor Engineering, New World Institute of Biotechnology, East China University of Science and Technology, Shanghai 200237, People’s Republic of China
| | - Dongzhi Wei
- State Key Laboratory of Bioreactor Engineering, New World Institute of Biotechnology, East China University of Science and Technology, Shanghai 200237, People’s Republic of China
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Petříčková A, Sosedov O, Baum S, Stolz A, Martínková L. Influence of point mutations near the active site on the catalytic properties of fungal arylacetonitrilases from Aspergillus niger and Neurospora crassa. ACTA ACUST UNITED AC 2012. [DOI: 10.1016/j.molcatb.2012.01.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Pawar SV, Meena VS, Kaushik S, Kamble A, Kumar S, Chisti Y, Banerjee UC. Stereo-selective conversion of mandelonitrile to (R)-(−)-mandelic acid using immobilized cells of recombinant Escherichia coli. 3 Biotech 2012. [PMCID: PMC3482447 DOI: 10.1007/s13205-012-0058-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Immobilized cells of a recombinant Escherichia coli expressing nitrilase from Pseudomonas putida were used to catalyze the hydrolysis of mandelonitrile (2-hydroxy-2-phenylacetonitrile) to (R)-(−)-mandelic acid. The cells had been immobilized by entrapment in an alginate matrix. Conditions for the hydrolysis reaction were optimized in shake flasks and in a packed bed reactor. In shake flasks the best conditions for the reaction were a temperature of 40 °C, pH 8, biocatalyst bead diameter of 4.3 mm, sodium alginate concentration in the gel matrix of 2 % (w/v, g/100 mL), a cell dry mass concentration in the bead matrix of 20 mg/mL, an initial substrate concentration of 50 mM and a reaction time of 60 min. Under these conditions, the conversion of mandelonitrile was nearly 95 %. In the packed bed reactor, a feed flow rate of 20 mL/h at a substrate concentration of 200 mM proved to be the best at 40 °C, pH 8, using 4.3 mm beads (2 % w/v sodium alginate in the gel matrix, 20 mg dry cell concentration per mL of gel matrix). This feed flow rate corresponded to a residence time of 0.975 h in the packed bed.
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Affiliation(s)
- Sandip V. Pawar
- Department of Pharmaceutical Technology (Biotechnology), National Institute of Pharmaceutical Education and Research, Sector-67, SAS Nagar, 160 062 Punjab, India
| | - Vachan Singh Meena
- Department of Pharmaceutical Technology (Biotechnology), National Institute of Pharmaceutical Education and Research, Sector-67, SAS Nagar, 160 062 Punjab, India
| | - Shubhangi Kaushik
- Department of Pharmaceutical Technology (Biotechnology), National Institute of Pharmaceutical Education and Research, Sector-67, SAS Nagar, 160 062 Punjab, India
| | - Ashwini Kamble
- Department of Pharmaceutical Technology (Biotechnology), National Institute of Pharmaceutical Education and Research, Sector-67, SAS Nagar, 160 062 Punjab, India
| | - Sandeep Kumar
- Department of Pharmaceutical Technology (Biotechnology), National Institute of Pharmaceutical Education and Research, Sector-67, SAS Nagar, 160 062 Punjab, India
| | - Yusuf Chisti
- School of Engineering, Massey University, Private Bag 11 222, Palmerston North, New Zealand
| | - U. C. Banerjee
- Department of Pharmaceutical Technology (Biotechnology), National Institute of Pharmaceutical Education and Research, Sector-67, SAS Nagar, 160 062 Punjab, India
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Baum S, Williamson DS, Sewell T, Stolz A. Conversion of sterically demanding α,α-disubstituted phenylacetonitriles by the arylacetonitrilase from Pseudomonas fluorescens EBC191. Appl Environ Microbiol 2012; 78:48-57. [PMID: 22020513 PMCID: PMC3255610 DOI: 10.1128/aem.05570-11] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Accepted: 10/12/2011] [Indexed: 11/20/2022] Open
Abstract
The nitrilase from Pseudomonas fluorescens EBC191 converted 2-methyl-2-phenylpropionitrile, which contains a quaternary carbon atom in the α-position toward the nitrile group, and also similar sterically demanding substrates, such as 2-hydroxy-2-phenylpropionitrile (acetophenone cyanohydrin) or 2-acetyloxy-2-methylphenylacetonitrile. 2-Methyl-2-phenylpropionitrile was hydrolyzed to almost stoichiometric amounts of the corresponding acid. Acetophenone cyanohydrin was transformed to the corresponding acid (atrolactate) and amide (atrolactamide) at a ratio of about 3.4:1. The (R)-acid and the (S)-amide were formed preferentially from acetophenone cyanohydrin. A homology model of the nitrilase suggested that steric hindrance with amino acid residue Tyr54 could impair the binding or conversion of sterically demanding substrates. Therefore, several enzyme variants that carried mutations in the respective residues were generated and subsequently analyzed for the substrate specificity and enantioselectivity of the reactions. Enzyme variants that demonstrated increased relative activities for the conversion of acetophenone cyanohydrin were identified. The chiral analysis of these reactions demonstrated peculiar reaction kinetics, which suggested that the enzyme variants converted the nonpreferred (S)-enantiomer of acetophenone cyanohydrin with a higher reaction rate than that of the (preferred) (R)-enantiomer. Recombinant whole-cell catalysts that simultaneously produced the nitrilase from P. fluorescens EBC191 and a plant-derived (S)-oxynitrilase from cassava (Manihot esculenta) converted acetophenone plus cyanide at pH 4.5 to (S)-atrolactate and (S)-atrolactamide. These recombinant cells are promising catalysts for the synthesis of stable chiral quaternary carbon centers from ketones.
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Affiliation(s)
- Stefanie Baum
- Institut für Mikrobiologie, Universität Stuttgart, Stuttgart, Germany
| | - Dael S. Williamson
- Electron Microscope Unit, University of Cape Town, Rondebosch, South Africa
| | - Trevor Sewell
- Electron Microscope Unit, University of Cape Town, Rondebosch, South Africa
| | - Andreas Stolz
- Institut für Mikrobiologie, Universität Stuttgart, Stuttgart, Germany
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Rustler S, Chmura A, Sheldon RA, Stolz A. Characterisation of the substrate specificity of the nitrile hydrolyzing system of the acidotolerant black yeast Exophiala oligosperma R1. Stud Mycol 2011; 61:165-74. [PMID: 19287539 PMCID: PMC2610300 DOI: 10.3114/sim.2008.61.17] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
The `black yeast' Exophiala oligosperma R1 can utilise various
organic nitriles under acidic conditions as nitrogen sources. The induction of
a phenylacetonitrile converting activity was optimised by growing the strain
in the presence of different nitriles and /or complex or inorganic nitrogen
sources. The highest nitrile hydrolysing activity was observed with cells
grown with 2-cyanopyridine and NaNO3. The cells metabolised the
inducer and grew with 2-cyanopyridine as sole source of nitrogen. Cell
extracts converted various (substituted) benzonitriles and
phenylacetonitriles. They usually converted the isomers carrying a substituent
in the meta-position with higher relative activities than the
corresponding para- or ortho-substituted isomers. Aliphatic
substrates such as acrylonitrile and 2-hydroxy-3-butenenitrile were also
hydrolysed. The highest specific activity was detected with 4-cyanopyridine.
Most nitriles were almost exclusively converted to the corresponding acids and
no or only low amounts of the corresponding amides were formed. The cells
hydrolysed amides only with extremely low activities. It was therefore
concluded that the cells harboured a nitrilase activity. The specific
activities of whole cells and cell extracts were compared for different
nitriles and evidence obtained for limitation in the substrate-uptake by whole
cells. The conversion of 2-hydroxy-3-butenenitrile to 2-hydroxy-3-butenoic
acid at pH 4 demonstrated the unique ability of cells of E.
oligosperma R1 to hydrolyse aliphatic α-hydroxynitriles under
acidic conditions. The organism could grow with phenylacetonitrile as sole
source of carbon, energy and nitrogen. The degradation of phenylacetonitrile
presumably proceeds via phenylacetic acid, 2-hydroxyphenylacetic acid,
2,5-dihydroxyphenylacetic acid (homogentisate), maleylacetoacetate and
fumarylacetoacetate.
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Affiliation(s)
- S Rustler
- Institut für Mikrobiologie, Universität Stuttgart, Allmandring 31, 70569 Stuttgart, Germany
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Yousefi M, Mohammadi M, Habibi Z, Cheraghi Z. Nitrile biotransformation by whole cells ofAspergillussp. PTCC 5266. BIOCATAL BIOTRANSFOR 2011. [DOI: 10.3109/10242422.2010.550002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Velankar H, Clarke KG, Preez RD, Cowan DA, Burton SG. Developments in nitrile and amide biotransformation processes. Trends Biotechnol 2010; 28:561-9. [DOI: 10.1016/j.tibtech.2010.08.004] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2010] [Revised: 07/29/2010] [Accepted: 08/13/2010] [Indexed: 10/19/2022]
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Construction and application of variants of the Pseudomonas fluorescens EBC191 arylacetonitrilase for increased production of acids or amides. Appl Environ Microbiol 2010; 76:3668-74. [PMID: 20382812 DOI: 10.1128/aem.00341-10] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The arylacetonitrilase from Pseudomonas fluorescens EBC191 differs from previously studied arylacetonitrilases by its low enantiospecificity during the turnover of mandelonitrile and by the large amounts of amides that are formed in the course of this reaction. In the sequence of the nitrilase from P. fluorescens, a cysteine residue (Cys163) is present in direct neighborhood (toward the amino terminus) to the catalytic active cysteine residue, which is rather unique among bacterial nitrilases. Therefore, this cysteine residue was exchanged in the nitrilase from P. fluorescens EBC191 for various amino acid residues which are present in other nitrilases at the homologous position. The influence of these mutations on the reaction specificity and enantiospecificity was analyzed with (R,S)-mandelonitrile and (R,S)-2-phenylpropionitrile as substrates. The mutants obtained demonstrated significant differences in their amide-forming capacities. The exchange of Cys163 for asparagine or glutamine residues resulted in significantly increased amounts of amides formed. In contrast, a substitution for alanine or serine residues decreased the amounts of amides formed. The newly discovered mutation was combined with previously identified mutations which also resulted in increased amide formation. Thus, variants which possessed in addition to the mutation Cys163Asn also a deletion at the C terminus of the enzyme and/or the modification Ala165Arg were constructed. These constructs demonstrated increased amide formation capacity in comparison to the mutants carrying only single mutations. The recombinant plasmids that encoded enzyme variants which formed large amounts of mandeloamide or that formed almost stoichiometric amounts of mandelic acid from mandelonitrile were used to transform Escherichia coli strains that expressed a plant-derived (S)-hydroxynitrile lyase. The whole-cell biocatalysts obtained in this way converted benzaldehyde plus cyanide either to (S)-mandeloamide or (S)-mandelic acid with high yields and enantiopurities.
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Identification of amino acid residues responsible for the enantioselectivity and amide formation capacity of the Arylacetonitrilase from Pseudomonas fluorescens EBC191. Appl Environ Microbiol 2009; 75:5592-9. [PMID: 19581475 DOI: 10.1128/aem.00301-09] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The nitrilase from Pseudomonas fluorescens EBC191 converted (R,S)-mandelonitrile with a low enantioselectivity to (R)-mandelic acid and (S)-mandeloamide in a ratio of about 4:1. In contrast, the same substrate was hydrolyzed by the homologous nitrilase from Alcaligenes faecalis ATCC 8750 almost exclusively to (R)-mandelic acid. A chimeric enzyme between both nitrilases was constructed, which represented in total 16 amino acid exchanges in the central part of the nitrilase from P. fluorescens EBC191. The chimeric enzyme clearly resembled the nitrilase from A. faecalis ATCC 8750 in its turnover characteristics for (R,S)-mandelonitrile and (R,S)-2-phenylpropionitrile (2-PPN) and demonstrated an even higher enantioselectivity for the formation of (R)-mandelic acid than the nitrilase from A. faecalis. An alanine residue (Ala165) in direct proximity to the catalytically active cysteine residue was replaced in the nitrilase from P. fluorescens by a tryptophan residue (as found in the nitrilase from A. faecalis ATCC 8750 and most other bacterial nitrilases) and several other amino acid residues. Those enzyme variants that possessed a larger substituent in position 165 (tryptophan, phenylalanine, tyrosine, or histidine) converted racemic mandelonitrile and 2-PPN to increased amounts of the R enantiomers of the corresponding acids. The enzyme variant Ala165His showed a significantly increased relative activity for mandelonitrile (compared to 2-PPN), and the opposite was found for the enzyme variants carrying aromatic residues in the relevant position. The mutant forms carrying an aromatic substituent in position 165 generally formed significantly reduced amounts of mandeloamide from mandelonitrile. The important effect of the corresponding amino acid residue on the reaction specificity and enantiospecificity of arylacetonitrilases was confirmed by the construction of a Trp164Ala variant of the nitrilase from A. faecalis ATCC 8750. This point mutation converted the highly R-specific nitrilase into an enzyme that converted (R,S)-mandelonitrile preferentially to (S)-mandeloamide.
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Sosedov O, Matzer K, Bürger S, Kiziak C, Baum S, Altenbuchner J, Chmura A, van Rantwijk F, Stolz A. Construction of RecombinantEscherichia coliCatalysts which Simultaneously Express an (S)-Oxynitrilase and Different Nitrilase Variants for the Synthesis of (S)-Mandelic Acid and (S)-Mandelic Amide from Benzaldehyde and Cyanide. Adv Synth Catal 2009. [DOI: 10.1002/adsc.200900087] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Seffernick JL, Samanta SK, Louie TM, Wackett LP, Subramanian M. Investigative mining of sequence data for novel enzymes: a case study with nitrilases. J Biotechnol 2009; 143:17-26. [PMID: 19539670 DOI: 10.1016/j.jbiotec.2009.06.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2008] [Revised: 06/08/2009] [Accepted: 06/09/2009] [Indexed: 10/20/2022]
Abstract
Mining sequence data is increasingly important for biocatalysis research. However, when relying on sequence data alone, prediction of the reaction catalyzed by a specific protein sequence is often elusive, and substrate specificity is far from trivial. The present study demonstrated an approach of combining sequence data and structures from distant homologs to target identification of new nitrilases that specifically utilize hindered nitrile substrates like mandelonitrile. A total of 212 non-identical target nitrilases were identified from GenBank. Evolutionary trace and sequence clustering methods were used combinatorily to identify a set of nitrilases with presumably distinct substrate specificities. Selected encoding genes were cloned into Escherichia coli. Recombinant E. coli expressing NitA (gi91784632) from Burkholderia xenovorans LB400 was capable of growth on glutaronitrile or adiponitrile as the sole nitrogen source. Purified NitA exhibited highest activity with mandelonitrile, showing a catalytic efficiency (k(cat)/K(m)) of 3.6 x 10(4)M(-1)s(-1). A second nitrilase predicted from our studies from Bradyrhizobium zaponicum USDA 110 (gi27381513) was likewise shown to prefer mandelonitrile [Zhu, D., Mukherjee, C., Biehl, E.R., Hua, L., 2007. Discovery of a mandelonitrile hydrolase from Bradyrhizobium japonicum USDA110 by rational genome mining. J. Biotechnol. 129 (4), 645-650]. Thus, predictions from sequence analysis and distant superfamily structures yielded enzyme activities with high selectivity for mandelonitrile. These data suggest that similar data mining techniques can be used to identify other substrate-specific enzymes from published, unannotated sequences.
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Affiliation(s)
- Jennifer L Seffernick
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, 140 Gortner Laboratory, St. Paul, MN 55108, USA.
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Rustler S, Motejadded H, Altenbuchner J, Stolz A. Simultaneous expression of an arylacetonitrilase from Pseudomonas fluorescens and a (S)-oxynitrilase from Manihot esculenta in Pichia pastoris for the synthesis of (S)-mandelic acid. Appl Microbiol Biotechnol 2008; 80:87-97. [DOI: 10.1007/s00253-008-1531-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2008] [Revised: 05/05/2008] [Accepted: 05/06/2008] [Indexed: 11/24/2022]
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Selection and screening for enzymes of nitrile metabolism. J Biotechnol 2008; 133:318-26. [DOI: 10.1016/j.jbiotec.2007.10.011] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2007] [Revised: 09/26/2007] [Accepted: 10/23/2007] [Indexed: 11/19/2022]
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Rustler S, Stolz A. Isolation and characterization of a nitrile hydrolysing acidotolerant black yeast-Exophiala oligosperma R1. Appl Microbiol Biotechnol 2007; 75:899-908. [PMID: 17361431 DOI: 10.1007/s00253-007-0890-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2007] [Revised: 02/13/2007] [Accepted: 02/13/2007] [Indexed: 11/30/2022]
Abstract
Different nitriles were used as sole sources of nitrogen in a series of enrichments under acidic conditions to isolate acidotolerant nitriles hydrolysing microorganisms. From an enrichment in Na-citrate-phosphate buffer at pH 4 with glucose as carbon source and phenylacetonitrile as sole source of nitrogen, a black yeast (strain R1) was obtained which was identified by subsequent 18S rRNA gene sequencing as Exophiala oligosperma. The growth conditions of the organism were optimized for the production of cell material and the induction of the nitrile converting activity. Resting cell experiments demonstrated that phenylacetonitrile was converted via phenylacetic acid and 2-hydroxyphenylacetic acid. The organism could grow at pH 4 with phenylacetonitrile as sole source of carbon, nitrogen, and energy. The nitriles hydrolysing activity was also detected in cell-free extracts and indications for a nitrilase activity were found. The cell-free extracts converted, in addition to phenylacetonitrile, also different substituted phenylacetonitriles. Whole cells of E. oligosperma R1 converted phenylacetonitrile with almost the same reaction rates in the pH range from pH 1.5-pH 9.
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Affiliation(s)
- Sven Rustler
- Institut für Mikrobiologie, Universität Stuttgart, Allmandring 31, 70569 Stuttgart, Germany
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