Nitrilase enzymes and their role in plant-microbe interactions.
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.
Affiliation: Department of Plant Sciences, University of Oxford, South Parks Road, Oxford, OX1 3RB, UK.Show MeSH
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Mentions: Nitrilases are frequently classified into one of three categories according to substrate specificity: aliphatic nitrilases, which act primarily on aliphatic nitriles such as acrylonitrile, glutaronitrile and β‐cyano‐l‐alanine; aromatic and heterocyclic nitrilases, which act primarily on aromatic or heterocyclic nitriles such as benzonitrile and cyanopyridine, and arylacetonitrilases which act primarily on arylacetonitriles such as indole‐3‐acetonitrile (IAN), phenylacetonitrile and phenylpropionitrile (Brenner, 2002; O'Reilly and Turner, 2003). Examples of each class of nitrile compound are shown in Fig. 2. Some nitrilases are extremely substrate specific, such as the nitrilase of Klebsiella pneumoniae sp. ozaenae and NIT4 of A. thaliana (McBride et al., 1986; Piotrowski et al., 2001), which catalyse the hydrolysis of bromoxynil and β‐cyano‐l‐alanine respectively. Other enzymes have a broad substrate range, such as the nitrilase of Bacillus pallidus Dac521, which hydrolyses aromatic, aliphatic and heterocyclic nitriles (Almatawah and Cowan, 1999; Almatawah et al., 1999). Nitrilases with the same substrate specificity often show amino acid sequence similarity and may fall within the same clade in phylogenetic analyses (Robertson et al., 2004; Podar et al., 2005; Howden et al., 2009). Figure 3 shows the phylogenetic relationship of a representative set of characterized nitrilases from different organisms. Within this tree are distinct groupings that in many cases correlate with the active substrate for enzyme activity.
Affiliation: Department of Plant Sciences, University of Oxford, South Parks Road, Oxford, OX1 3RB, UK.