Hydration of a N-cyanoimine group to a N-carbamoylimine by NHase

Degradation of the Neonicotinoid Insecticide Acetamiprid via the N-Carbamoylimine Derivate (IM-1-2) Mediated by the Nitrile Hydratase of the Nitrogen-Fixing …

LY Zhou, LJ Zhang, SL Sun, F Ge, SY Mao, Y Ma, ZH Liu, YJ Dai, and S Yuan J. Agric. Food Chem., 2014, 62 (41), pp 9957–9964

The metabolism of the widely used neonicotinoid insecticide acetamiprid (ACE) has been extensively studied in plants, animals, soils, and microbes. However, hydration of the N-cyanoimine group in ACE to the N-carbamoylimine derivate (IM-1-2) by purified microbes, the enzyme responsible for this biotransformation, and further degradation of IM-1-2 have not been studied. The present study used liquid chromatography–mass spectrometry and nuclear magnetic resonance spectroscopy to determine that the nitrogen-fixing bacterium Ensifer meliloti CGMCC 7333 transforms ACE to IM-1-2. CGMCC 7333 cells degraded 65.1% of ACE in 96 h, with a half-life of 2.6 days. Escherichia coli Rosetta (DE3) overexpressing the nitrile hydratase (NHase) from CGMCC 7333 and purified NHase converted ACE to IM-1-2 with degradation ratios of 97.1% in 100 min and 93.9% in 120 min, respectively. Interestingly, IM-1-2 was not further degraded by CGMCC 7333, whereas it was spontaneously hydrolyzed at the N-carbamoylimine group to the derivate ACE-NH, which was further converted to the derivative ACE-NH2. Then, ACE-NH2 was cleaved to the major metabolite IM-1-4. IM-1-2 showed significantly lower insecticidal activity than ACE against the aphid Aphis craccivora Koch. The present findings will improve the understanding of the environmental fate of ACE and the corresponding enzymatic mechanisms of degradation.

Surface modification of polyacrylonitrile fibre by NHase

Surface Modification of Polyacrylonitrile Fibre by Nitrile Hydratase from Corynebacterium nitrilophilus

S Chen, H Gao, J Chen, J Wu - Applied biochemistry and biotechnology, 2014

Previously, nitrile hydratase (NHase) from Corynebacterium nitrilophilus was obtained and showed potential in polyacrylonitrile (PAN) fibre modification. In the present study, the modification conditions of C. nitrilophilus NHase on PAN were investigated. In the optimal conditions, the wettability and dyeability (anionic and reactive dyes) of PAN treated by C. nitrilophilus NHase reached a similar level of those treated by alkali. In addition, the chemical composition and microscopically observable were changed in the PAN surface after NHase treatment. Meanwhile, it revealed that cutinase combined with NHase facilitates the PAN hydrolysis slightly because of the ester existed in PAN as co-monomer was hydrolyzed. All these results demonstrated that C. nitrilophilus NHase can modify PAN efficiently without textile structure damage, and this study provides a foundation for the further application of C. nitrilophilus NHase in PAN modification industry.

NHase patent on stabilizing nitrile active enzymes in cells

Methods for preserving and/or storing cells having a nitrilase or nitrile hydratase activity

T Zelinski, M Keβeler, B Hauer - US Patent 8,815,569, 2014

The invention from BASF relates to a method for preserving and/or storing microorganisms which exhibit at least one nitrile hydratase or nitrilase enzyme activity, with the preservation and/or storage being effected in an aqueous medium which comprises at least one aldehyde, with the total aldehyde concentration being in a range from 0.1 to 100 mM/l.

Book chapter on sulfur oxygenation and functional models of NHase

Chapter 12 in the book “Bioinspired Catalysis”

Authors: Davinder Kumar and Craig A. Grapperhaus

This chapter highlights selected complexes with tetra- and penta-dentate chelates that provide key insights into the oxidized sulfur environment at the enzyme active site. Small-molecule mimics with variable S-oxidation levels provide an attractive method to address these interactions. It discusses a brief history of metal-thiolate sulfur-oxygenation is provided, followed by selected S-oxygenation studies relevant to nitrile hydratase (NHase). The NHase are divided by metal type and organized according to the donor atoms of the chelates. Several ruthenium catalysts have been reported as nitrile hydration catalysts. Ruthenium is also a logical choice for oxidation studies as the second-row transition metal maintains a consistent low spin, which was found to promote S-oxygenation.

A switch in a substrate tunnel for directing regioselectivity of nitrile hydratases towards α,ω-dinitriles

A switch in a substrate tunnel for directing regioselectivity of nitrile hydratases towards α,ω-dinitriles

Zhongyi Cheng, Wenjing Cui, Zhongmei Liu, Li Zhou, Min Wang, Michihiko Kobayashi and Zhemin Zhou 

The β37 residue of nitrile hydratase (NHase) from Pseudomonas putida and NHase from Comamonas testosteroni played a critical role in directing enzyme regioselectivity. Amino acid substitution in this site modulated or even inverted enzyme regioselectivity towards aliphatic α,ω-dinitriles.

Cartoon model of the substrate access tunnel of (a) wild-type PpNHase and its (b) L37F and (c) L37Y variants, and (d) wild-type CtNHase and its (e) F37L and (f) F37P variants. The protein structures of PpNHase and CtNHase are shown as the grey cartoon. The β37 residues of NHases are shown as blue sticks. The purple balls and sticks represent the catalytic site of NHase. The bottleneck-forming amino acids are shown as red sticks. The tunnels are shown as green spheres, and the tunnel bottlenecks are coloured in yellow. All the figures share the same size proportion.

The Alpha Subunit of Nitrile Hydratase Is Sufficient for Catalytic Activity

That’s a title which is going to catch the eye.

Nitrile hydratases have two subunits, the alpha and beta, they zip together like the two bits of rubber that make a tennis ball and the active site sits in between the two, protecting the weird metallic centre from the all the life can throw at it. Here's a crystal structure (1UGP) with one subunit in light blue, the other in dark blue and the seam marked by red and green,

A new paper in Biochemistry (DOI: 10.1021/bi500260j) by Bandarian and co-workers describe a toyocamycin nitrile hydratase from Streptomyces rimosus which has three subunits. Toyocamycin is a pyrrolopyrimidine compound. Of the three subunits, one is similar to your usual alpha unit (ToyJ), one (ToyL) is similar to the front half of the beta subunit and the final bit (ToyK) is similar to the end of the beta subunit (diagram below from the paper using 1IRE as scaffold). These subunits were all cloned into E. coli and they produce pure recombinant ToyJKL which is orange and is shown to be a cobalt centred NHase. The amazing bit that happens after that is that they get ToyJ to express well by itself and able to hold the cobalt needed in the active site. They then show that this active protein can turn over its desired substrate nitrile (admittedly not as well as the full complex), and also 3-cyanopyridine. The authors speculate that the ToyKL bits might add substrate specificity, but as you might imagine this early in this research there is no structural data on the enzyme complex.

 

Nitrilase and nitrile hydratase from Pseudomonas sp. UW4

Having just finished a project where we looked at a range of nitrilases and what their preferred substrates are, it is always interesting to ponder what the bacterium actually wanted the enzyme for (as compared to the host of xenobiotics you threw at it). We have often had the situation where we have an enzyme which we reckon ought to be active but doesn't seem interested in any of the forty or so compounds we have in our simple screen.
There is a recent paper in Applied and Environmental Microbiology by Duca, Rose and Glick which is concerned with investigating the biosynthesis of indoleacetic acid (IAA), which is a plant growth hormone. This compound comes from indoleacetonitrile (IAN) and there are two obvious pathways to get from there to IAA- via the NHase and via a nitrilase. These workers cloned both enzymes in to E. coli, and then looked at their level of interest in IAN. Interestingly the nitrilase had a habit of producing a proportion of amide as well as the usual acid. Also of interest is that the enzymes have different pH and temperature optima (Nase like 50 degrees C and pH6, the iron-centred NHase likes 4 degrees C and pH7.5), though I wonder if the lower temperature for the NHase is due to the fundamental lack of stability of iron NHases rather than an adaption. Additionally, the authors use some bioinformatics to confirm their experimental findings that this is an aromatic nitrile active system.