title: Cyanide detoxification in an insect herbivore: Molecular identification of β-cyanoalanine synthases from Pieris rapae.
abstract: Cyanogenic compounds occur widely in the plant kingdom. Therefore, many herbivores are adapted to the presence of these compounds in their diet by either avoiding cyanide release or by efficient cyanide detoxification mechanisms. The mechanisms of adaptation are not fully understood. Larvae of Pieris rapae (Lepidoptera: Pieridae) are specialist herbivores on glucosinolate-containing plants. They are exposed to cyanide during metabolism of phenylacetonitrile, a product of benzylglucosinolate breakdown catalyzed by plant myrosinases and larval nitrile-specifier protein (NSP) in the gut. Cyanide is metabolized to β-cyanoalanine and thiocyanate in the larvae. Here, we demonstrate that larvae of P. rapae possess β-cyanoalanine activity in their gut. We have identified three gut-expressed cDNAs designated PrBSAS1-PrBSAS3 which encode proteins with similarity to β-substituted alanine synthases (BSAS). Characterization of recombinant PrBSAS1-PrBSAS3 shows that they possess β-cyanoalanine activity. In phylogenetic trees, PrBSAS1-PrBSAS3, the first characterized insect BSAS, group together with a characterized mite β-cyanoalanine synthase and bacterial enzymes indicating a similar evolutionary history.
authors.affiliation: Institute of Pharmaceutical Biology, Technische Universität Braunschweig, Mendelssohnstr. 1, 38106 Braunschweig, Germany.
authors.forename: Maike
authors.initials: M
authors.lastname: van Ohlen
authors.affiliation: Institute of Pharmaceutical Biology, Technische Universität Braunschweig, Mendelssohnstr. 1, 38106 Braunschweig, Germany.
authors.forename: Anna-Maria
authors.initials: AM
authors.lastname: Herfurth
authors.affiliation: Institute of Pharmaceutical Biology, Technische Universität Braunschweig, Mendelssohnstr. 1, 38106 Braunschweig, Germany.
authors.forename: Henrike
authors.initials: H
authors.lastname: Kerbstadt
authors.affiliation: Institute of Pharmaceutical Biology, Technische Universität Braunschweig, Mendelssohnstr. 1, 38106 Braunschweig, Germany. Electronic address: u.wittstock@tu-bs.de.
authors.forename: Ute
authors.initials: U
authors.lastname: Wittstock
mesh_terms: D000818:Animals; D017360:Arabidopsis; D002080:Butterflies / Q000201:enzymology / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D003486:Cyanides / Q000378:metabolism*; D004790:Enzyme Induction; D060434:Herbivory; D008190:Lyases / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism*; D013058:Mass Spectrometry
chemical_list: D003486:Cyanides; D008190:Lyases; C019955:beta-cyanoalanine synthase
keywords: Cyanide detoxification; Glucosinolate; O-acetylserine (thiol) lyase; Pieris rapae; β-cyanoalanine synthase