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Siegfried Brunner, Erik Eppinger, Stefanie Fischer, Janosch Gröning, Andreas Stolz
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...
June 12, 2018: World Journal of Microbiology & Biotechnology
Shi-Lei Sun, Wen-Long Yang, Wen-Wan Fang, Yun-Xiu Zhao, Ling Guo, Yi-Jun Dai
Variovorax is a metabolically diverse genus of plant growth-promoting rhizobacteria (PGPR) that engages in mutually beneficial interactions between plants and microbes. Unlike most PGPR, Variovorax cannot synthesize the phytohormone indole-3-acetic acid (IAA) via tryptophan. However, we found that V. boronicumulans strain CGMCC 4969 could produce IAA using indole-3-acetonitrile (IAN) as the precursor. Thus, in the present study, the IAA synthesis mechanism of V. boronicumulans CGMCC 4969 was investigated. V...
June 8, 2018: Applied and Environmental Microbiology
Wei Cheng, Declan A Doyle, Toufic El Arnaout
Bacterial lipoproteins have been researched for decades due to their roles in a large number of biological functions. There were no structures of their main three membrane processing enzymes, until 2016 for Lgt and LspA, and then 2017 for Lnt with not one but three simultaneous, independent publications. We have analyzed the recent findings for this N-acyltransferase Lnt, with comparisons between the novel structures, and with soluble nitrilases, to determine the significance of unique features in terms of substrate's recognition and binding mechanism influenced by exclusive residues, two transmembrane helices, and a flexible loop...
May 31, 2018: International Journal of Biological Macromolecules
Konstantin V Lavrov, Anna O Shemyakina, Elena G Grechishnikova, Andrey D Novikov, Denis D Derbikov, Tatyana I Kalinina, Alexander S Yanenko
Rhodococcus strains are important biocatalysts used for biotechnological production of acrylamide catalysed by a nitrile hydratase (NHase) containing cobalt. This metalloenzyme is present at high intracellular concentrations representing up to 50% of the soluble proteins in Rhodococcus rhodochrous M8 strain. Cobalt ions were formerly reported to be essential for the synthesis of the NHase subunits, encoded by nhmBA structural genes in R. rhodochrous M8. To understand the regulatory mechanisms enabling high expression of the NHase structural genes by cobalt, two reporter genes coding for an acylamidase from Rhodococcus erythropolis TA37 and a nitrilase from Alcaligenes denitrificans C-32 were fused to the nhmBA promoter...
May 22, 2018: Research in Microbiology
Lauren B Jones, Pallab Ghosh, Jung-Hyun Lee, Chia-Ni Chou, Daniel A Kunz
A genetic linkage between a conserved gene cluster (Nit1C) and the ability of bacteria to utilize cyanide as the sole nitrogen source was demonstrated for nine different bacterial species. These included three strains whose cyanide nutritional ability has formerly been documented (Pseudomonas fluorescens Pf11764, Pseudomonas putida BCN3 and Klebsiella pneumoniae BCN33), and six not previously known to have this ability [Burkholderia (Paraburkholderia) xenovorans LB400, Paraburkholderia phymatum STM815, Paraburkholderia phytofirmans PsJN, Cupriavidus (Ralstonia) eutropha H16, Gluconoacetobacter diazotrophicus PA1 5 and Methylobacterium extorquens AM1]...
May 21, 2018: Microbiology
Daniel Vik, Namiko Mitarai, Nikolai Wulff, Barbara A Halkier, Meike Burow
Plants release chemicals to deter attackers. Arabidopsis thaliana relies on multiple defense compounds, including indol-3-ylmethyl glucosinolate (I3G), which upon hydrolysis initiated by myrosinase enzymes releases a multitude of bioactive compounds, among others, indole-3-acetonitrile and indole-3-acetoisothiocyanate. The highly unstable isothiocyanate rapidly reacts with other molecules. One of the products, indole-3-carbinol, was reported to inhibit auxin signaling through binding to the TIR1 auxin receptor...
2018: Frontiers in Plant Science
Zhi-Qiang Liu, Ming-Ming Lu, Xin-Hong Zhang, Feng Cheng, Jian-Miao Xu, Ya-Ping Xue, Li-Qun Jin, Yuan-Shan Wang, Yu-Guo Zheng
Iminodiacetic acid (IDA) is widely used as an intermediate in the manufacturing of chelating agents, glyphosate herbicides and surfactants. To improve activity and tolerance to the substrate for IDA production, Acidovorax facilis nitrilase was selected for further modification by the gene site saturation mutagenesis method. After screened by a two-step screening method, the best mutant (Mut-F168V/T201N/S192F/M191T/F192S) was selected. Compared to the wild-type nitrilase, Mut-F168V/T201N/S192F/M191T/F192S showed 136% improvement in specific activity...
May 9, 2018: International Journal of Biological Macromolecules
Zhi-Jun Zhang, Rui-Feng Cai, Jian-He Xu
A nitrilase from Hoeflea phototrophica DFL-43 (HpN) demonstrating excellent catalytic activity towards benzoylacetonitrile was identified from a nitrilase tool-box, which was developed previously in our laboratory for (R)-o-chloromandelic acid synthesis from o-chloromandelonitrile. The HpN was overexpressed in Escherichia coli BL21 (DE3), purified to homogeneity by nickel column affinity chromatography, and its biochemical properties were studied. The HpN was very stable at 30-40 °C, and highly active over a wide range of pH values (pH 6...
May 10, 2018: Applied Microbiology and Biotechnology
Madhulika Kushwaha, Virender Kumar, Rishi Mahajan, Tek Chand Bhalla, Subhankar Chatterjee, Yusuf Akhter
The present study provides molecular insights into the activity and mechanism of cyanide hydratase enzyme associated with degradation of cyanide compounds, using Serratia marcescens RL2b as a model organism. Resting cells harvested after 20 h achieved complete degradation of 12 mmol l- 1 cyanide in approximately 10 h. High-performance liquid chromatography analysis of reaction samples revealed formation of formamide as the only end product, which confirmed the presence of cyanide hydratase activity in S...
May 9, 2018: Archives of Microbiology
Zhiqiang Yao, Shuiqin Jiang, Lujia Zhang, Bei Gao, Xiao He, John Z H Zhang, Dongzhi Wei
The study of enzyme substrate specificity is vital for developing potential applications of enzymes. However, the routine experimental procedures require lot of resources in the discovery of novel substrates. This article reports an in silico structure-based algorithm called Crius, which predicts substrates for enzyme. The results of this fragment-based algorithm show good agreements between the simulated and experimental substrate specificities, using a lipase from Candida antarctica (CALB), a nitrilase from Cyanobacterium syechocystis sp...
May 3, 2018: Protein Science: a Publication of the Protein Society
Robert Rädisch, Martin Chmátal, Lenka Rucká, Petr Novotný, Lucie Petrásková, Petr Halada, Michael Kotik, Miroslav Pátek, Ludmila Martínková
Almost 100 genes within the genus Bradyrhizobium are known to potentially encode aldoxime dehydratases (Oxds), but none of the corresponding proteins have been characterized yet. Aldoximes are natural substances involved in plant defense and auxin synthesis, and Oxds are components of enzymatic cascades enabling bacteria to transform, utilize and detoxify them. The aim of this work was to characterize a representative of the highly conserved Oxds in Bradyrhizobium spp. which include both plant symbionts and members of the soil communities...
April 23, 2018: International Journal of Biological Macromolecules
Nanna Bjarnholt, Elizabeth H J Neilson, Christoph Crocoll, Kirsten Jørgensen, Mohammed Saddik Motawia, Carl Erik Olsen, David P Dixon, Robert Edwards, Birger Lindberg Møller
Cyanogenic glucosides are nitrogen-containing specialized metabolites that provide chemical defense against herbivores and pathogens via the release of toxic hydrogen cyanide. It has been suggested that cyanogenic glucosides are also a store of nitrogen that can be remobilized for general metabolism via a previously unknown pathway. Here we reveal a recycling pathway for the cyanogenic glucoside dhurrin in sorghum (Sorghum bicolor) that avoids hydrogen cyanide formation. As demonstrated in vitro, the pathway proceeds via spontaneous formation of a dhurrin-derived glutathione conjugate, which undergoes reductive cleavage by glutathione transferases of the plant-specific lambda class (GSTLs) to produce p-hydroxyphenyl acetonitrile...
June 2018: Plant Journal: for Cell and Molecular Biology
Jin-Song Gong, Qiang Zhang, Bing-Chen Gu, Ting-Ting Dong, Heng Li, Hui Li, Zhen-Ming Lu, Jin-Song Shi, Zheng-Hong Xu
The constitutively expression system for P. putida nitrilase was firstly constructed to improve the nicotinic acid production and reduce the production costs. High density culture strategy was employed to enhance the biomass and nitrilase production of recombinant strain. The total nitrilase activity reached up to 654 U·mL-1 without the induction. 541 g·L-1 nicotinic acid was accumulated via fed batch mode of substrate feeding through 290 min of conversion.
July 2018: Bioresource Technology
Zhe Xu, Ting Cai, Neng Xiong, Shu-Ping Zou, Ya-Ping Xue, Yu-Guo Zheng
Nitrilases can hydrolyze nitriles to corresponding carboxylic acids in one single step, which have great potential as valuable biocatalysts for chemical synthesis. However, the poor thermostability of the nitrilases restrict their applications in industry. In this work, error-prone PCR and site-directed mutagenesis were utilized to improve the thermostability of nitrilases. Several mutants (AcN-Q339K, AcN-Q343K, AcN-T201F, AcN-T201W, AcN-T201L, AcN-T201I) were obtained with dramatically improved thermostability...
June 2018: Enzyme and Microbial Technology
Ludmila Martínková, Vladimír Křen
The aim of this study is to summarize the current progress in the design of biocatalytic processes applicable for the production of optically pure mandelic acids and their analogues. These compounds are used as building blocks for pharmaceutical chemistry and as chiral resolving agents. Their enzymatic syntheses mainly employed nitrile hydrolysis with nitrilases, ester hydrolysis, ammonolysis or esterification with lipases or esterases, and ketone reduction or alcohol oxidation with dehydrogenases. Each of these methods will be characterized in terms of its product concentrations, enantioselectivities, and the types of catalysts used...
May 2018: Applied Microbiology and Biotechnology
Renu Singh, Anirban Banerjee, Praveen Kaul, Brajesh Barse, U C Banerjee
In the original version of our paper entitled "Release of an enantioselective nitrilase from Alcaligenes faecalis MTCC 126: a comparative study" (2005) 27:415-424, some references to already published articles were inadvertently left out.
February 24, 2018: Bioprocess and Biosystems Engineering
Tek Chand Bhalla, Vijay Kumar, Virender Kumar, Neerja Thakur, Savitri
Nitrile metabolizing enzymes, i.e., aldoxime dehydratase, hydroxynitrile lyase, nitrilase, nitrile hydratase, and amidase, are the key catalysts in carbon nitrogen triple bond anabolism and catabolism. Over the past several years, these enzymes have drawn considerable attention as prominent biocatalysts in academia and industries because of their wide applications. Research on various aspects of these biocatalysts, i.e., sources, screening, function, purification, molecular cloning, structure, and mechanisms, has been conducted, and bioprocesses at various scales have been designed for the synthesis of myriads of useful compounds...
January 30, 2018: Applied Biochemistry and Biotechnology
Nikhil Sharma, Ruchi Verma, Savitri, Tek Chand Bhalla
ProCos (Protein Composition Server, script version), one of the machine learning techniques, was used to classify nitrilases as aliphatic and aromatic nitrilases. Some important feature vectors were used to train the algorithm, which included pseudo-amino acid composition (PAAC) and five-factor solution score (5FSS). This clearly differentiated into two groups of nitrilases, i.e., aliphatic and aromatic, achieving maximum sensitivity of 100.00%, specificity of 90.00%, accuracy of 95.00% and Mathew Correlation Coefficient (MCC) of about 0...
January 2018: 3 Biotech
Michael J Benedik, B Trevor Sewell
No abstract text is available yet for this article.
December 30, 2017: Journal of General and Applied Microbiology
Heidi Fisk, Yun Xu, Chloe Westley, Nicholas J Turner, Jason Micklefield, Royston Goodacre
Process analytical technologies (PAT) are used within industry to give real-time measurements of critical quality parameters, ultimately improving the quality by design (QbD) of the final product and reducing manufacturing costs. Spectroscopic and spectrophotometric methods are readily employed within PAT due to their ease of use, compatibility toward a range of sample types, robustness, and multiplexing capabilities. We have developed a UV resonance Raman (UVRR) spectroscopy approach to quantify industrially relevant biotransformations accurately, focusing on nitrile metabolizing enzymes: nitrile hydratase (NHase) and amidase versus nitrilase activity...
November 21, 2017: Analytical Chemistry
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