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Nitrilase enzymes and their role in plant-microbe interactions.

Howden AJ, Preston GM - Microb Biotechnol (2009)

Bottom Line: In the context of plant-microbe interactions they may have roles in hormone synthesis, nutrient assimilation and detoxification of exogenous and endogenous nitriles.Nitrilases are produced by both plant pathogenic and plant growth-promoting microorganisms, and their activities may have a significant impact on the outcome of plant-microbe interactions.In this paper we review current knowledge of the role of nitriles and nitrilases in plants and plant-associated microorganisms, and discuss how greater understanding of the natural functions of nitrilases could be applied to benefit both industry and agriculture.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Sciences, University of Oxford, South Parks Road, Oxford, OX1 3RB, UK.

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Ethylene, cyanide and β‐cyano‐l‐alanine synthesis in plants. When plants synthesize ethylene they also produce cyanide as a co‐product. Cyanide is converted to β‐cyano‐l‐alanine which is subsequently detoxified by a NIT4‐type nitrilase to aspartic acid and ammonia. Asparagine is also produced in this reaction because NIT4 displays β‐cyano‐l‐alanine‐hydratase activity (Piotrowski et al., 2001). Enzymes are shown in italics. SAM, S‐adenosyl‐l‐methionine; ACC, 1‐aminocyclopropane‐1‐carboxylic acid. This figure was adapted from Davies (1995).
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f4: Ethylene, cyanide and β‐cyano‐l‐alanine synthesis in plants. When plants synthesize ethylene they also produce cyanide as a co‐product. Cyanide is converted to β‐cyano‐l‐alanine which is subsequently detoxified by a NIT4‐type nitrilase to aspartic acid and ammonia. Asparagine is also produced in this reaction because NIT4 displays β‐cyano‐l‐alanine‐hydratase activity (Piotrowski et al., 2001). Enzymes are shown in italics. SAM, S‐adenosyl‐l‐methionine; ACC, 1‐aminocyclopropane‐1‐carboxylic acid. This figure was adapted from Davies (1995).

Mentions: Nitriles are also present in plants as intermediates in cyanide metabolism. Cyanide is synthesized by plants during defence responses, as mentioned above, but also as a co‐product of ethylene biosynthesis. Ethylene is synthesized from 1‐aminocyclopropane‐1‐carboxylic acid with the release of CO2 and HCN (Peiser et al., 1984). Free cyanide and cysteine are metabolized to the nitrile β‐cyano‐l‐alanine by the enzyme β‐cyano‐l‐alanine synthase (Floss et al., 1965; Blumenthal et al., 1968). β‐Cyano‐l‐alanine is a potent neurotoxin and may accumulate in the tissues of some plants, such as vetch (Vicia), to be used as an anti‐herbivory agent (Vannesland et al., 1981; Ressler et al., 1997). However, in most plants β‐cyano‐l‐alanine is quickly detoxified by nitrilase activity to aspartic acid, asparagine and ammonia. The reactions linking ethylene biosynthesis with cyanide and β‐cyano‐l‐alanine production are shown in Fig. 4.


Nitrilase enzymes and their role in plant-microbe interactions.

Howden AJ, Preston GM - Microb Biotechnol (2009)

Ethylene, cyanide and β‐cyano‐l‐alanine synthesis in plants. When plants synthesize ethylene they also produce cyanide as a co‐product. Cyanide is converted to β‐cyano‐l‐alanine which is subsequently detoxified by a NIT4‐type nitrilase to aspartic acid and ammonia. Asparagine is also produced in this reaction because NIT4 displays β‐cyano‐l‐alanine‐hydratase activity (Piotrowski et al., 2001). Enzymes are shown in italics. SAM, S‐adenosyl‐l‐methionine; ACC, 1‐aminocyclopropane‐1‐carboxylic acid. This figure was adapted from Davies (1995).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3815905&req=5

f4: Ethylene, cyanide and β‐cyano‐l‐alanine synthesis in plants. When plants synthesize ethylene they also produce cyanide as a co‐product. Cyanide is converted to β‐cyano‐l‐alanine which is subsequently detoxified by a NIT4‐type nitrilase to aspartic acid and ammonia. Asparagine is also produced in this reaction because NIT4 displays β‐cyano‐l‐alanine‐hydratase activity (Piotrowski et al., 2001). Enzymes are shown in italics. SAM, S‐adenosyl‐l‐methionine; ACC, 1‐aminocyclopropane‐1‐carboxylic acid. This figure was adapted from Davies (1995).
Mentions: Nitriles are also present in plants as intermediates in cyanide metabolism. Cyanide is synthesized by plants during defence responses, as mentioned above, but also as a co‐product of ethylene biosynthesis. Ethylene is synthesized from 1‐aminocyclopropane‐1‐carboxylic acid with the release of CO2 and HCN (Peiser et al., 1984). Free cyanide and cysteine are metabolized to the nitrile β‐cyano‐l‐alanine by the enzyme β‐cyano‐l‐alanine synthase (Floss et al., 1965; Blumenthal et al., 1968). β‐Cyano‐l‐alanine is a potent neurotoxin and may accumulate in the tissues of some plants, such as vetch (Vicia), to be used as an anti‐herbivory agent (Vannesland et al., 1981; Ressler et al., 1997). However, in most plants β‐cyano‐l‐alanine is quickly detoxified by nitrilase activity to aspartic acid, asparagine and ammonia. The reactions linking ethylene biosynthesis with cyanide and β‐cyano‐l‐alanine production are shown in Fig. 4.

Bottom Line: In the context of plant-microbe interactions they may have roles in hormone synthesis, nutrient assimilation and detoxification of exogenous and endogenous nitriles.Nitrilases are produced by both plant pathogenic and plant growth-promoting microorganisms, and their activities may have a significant impact on the outcome of plant-microbe interactions.In this paper we review current knowledge of the role of nitriles and nitrilases in plants and plant-associated microorganisms, and discuss how greater understanding of the natural functions of nitrilases could be applied to benefit both industry and agriculture.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Sciences, University of Oxford, South Parks Road, Oxford, OX1 3RB, UK.

Show MeSH
Related in: MedlinePlus