| Title: | The nitrilase PtNIT1 catabolizes herbivore-induced nitriles in Populus trichocarpa |
| Author(s): | Gunther J; Irmisch S; Lackus ND; Reichelt M; Gershenzon J; Kollner TG; |
| Address: | "Max Planck Institute for Chemical Ecology, Hans-Knoll-Strasse 8, D-07745, Jena, Germany. Present Address: Michael Smith Laboratories, University of British Columbia, Vancouver, Canada. Max Planck Institute for Chemical Ecology, Hans-Knoll-Strasse 8, D-07745, Jena, Germany. koellner@ice.mpg.de" |
| DOI: | 10.1186/s12870-018-1478-z |
| ISSN/ISBN: | 1471-2229 (Electronic) 1471-2229 (Linking) |
| Abstract: | "BACKGROUND: Nitrilases are nitrile-converting enzymes commonly found within the plant kingdom that play diverse roles in nitrile detoxification, nitrogen recycling, and phytohormone biosynthesis. Although nitrilases are present in all higher plants, little is known about their function in trees. Upon herbivory, poplars produce considerable amounts of toxic nitriles such as benzyl cyanide, 2-methylbutyronitrile, and 3-methylbutyronitrile. In addition, as byproduct of the ethylene biosynthetic pathway upregulated in many plant species after herbivory, toxic beta-cyanoalanine may accumulate in damaged poplar leaves. In this work, we studied the nitrilase gene family in Populus trichocarpa and investigated the potential role of the nitrilase PtNIT1 in the catabolism of herbivore-induced nitriles. RESULTS: A BLAST analysis revealed three putative nitrilase genes (PtNIT1, PtNIT2, PtNIT3) in the genome of P. trichocarpa. While PtNIT1 was expressed in poplar leaves and showed increased transcript accumulation after leaf herbivory, PtNIT2 and PtNIT3 appeared not to be expressed in undamaged or herbivore-damaged leaves. Recombinant PtNIT1 produced in Escherichia coli accepted biogenic nitriles such as beta-cyanoalanine, benzyl cyanide, and indole-3-acetonitrile as substrates in vitro and converted them into the corresponding acids. In addition to this nitrilase activity, PtNIT1 showed nitrile hydratase activity towards beta-cyanoalanine, resulting in the formation of the amino acid asparagine. The kinetic parameters of PtNIT1 suggest that the enzyme utilizes beta-cyanoalanine and benzyl cyanide as substrates in vivo. Indeed, beta-cyanoalanine and benzyl cyanide were found to accumulate in herbivore-damaged poplar leaves. The upregulation of ethylene biosynthesis genes after leaf herbivory indicates that herbivore-induced beta-cyanoalanine accumulation is likely caused by ethylene formation. CONCLUSIONS: Our data suggest a role for PtNIT1 in the catabolism of herbivore-induced beta-cyanoalanine and benzyl cyanide in poplar leaves" |
| Keywords: | Alanine/analogs & derivatives/metabolism Aminohydrolases/genetics/*metabolism Herbivory Nitriles/*metabolism Plant Leaves/enzymology/genetics Populus/*enzymology/genetics Benzyl cyanide Nit1 Nitrilase Plant defense Populus trichocarpa beta-Cyanoalanine; |
| Notes: | "MedlineGunther, Jan Irmisch, Sandra Lackus, Nathalie D Reichelt, Michael Gershenzon, Jonathan Kollner, Tobias G eng England 2018/10/24 BMC Plant Biol. 2018 Oct 22; 18(1):251. doi: 10.1186/s12870-018-1478-z" |
