Characterisation of aphid myrosinase and degradation studies of glucosinolates

Francis, Frédéric; Lognay, Georges; Wathelet, Jean‐Paul; Haubruge, Éric

doi:10.1002/arch.10042

Cited by 57 publications

(52 citation statements)

References 39 publications

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“…Aliphatic glucosinolates were the preferred substrates of the flea beetle myrosinase, with aromatic and indolic glucosinolates and two different standard β-O-glucoside substrates being hydrolyzed at much lower efficiencies. The previously identified aphid myrosinase from B. brassicae (40-42) displays much broader substrate specificity (41,43).…”

Section: Discussionmentioning

confidence: 98%

Phyllotreta striolataflea beetles use host plant defense compounds to create their own glucosinolate-myrosinase system

Beran¹,

Pauchet²,

Kunert

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

112

143

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The ability of a specialized herbivore to overcome the chemical defense of a particular plant taxon not only makes it accessible as a food source but may also provide metabolites to be exploited for communication or chemical defense. Phyllotreta flea beetles are adapted to crucifer plants (Brassicales) that are defended by the glucosinolate-myrosinase system, the so-called "mustard-oil bomb." Tissue damage caused by insect feeding brings glucosinolates into contact with the plant enzyme myrosinase, which hydrolyzes them to form toxic compounds, such as isothiocyanates. However, we previously observed that Phyllotreta striolata beetles themselves produce volatile glucosinolate hydrolysis products. Here, we show that P. striolata adults selectively accumulate glucosinolates from their food plants to up to 1.75% of their body weight and express their own myrosinase. By combining proteomics and transcriptomics, a gene responsible for myrosinase activity in P. striolata was identified. The major substrates of the heterologously expressed myrosinase were aliphatic glucosinolates, which were hydrolyzed with at least fourfold higher efficiency than aromatic and indolic glucosinolates, and β-O-glucosides. The identified beetle myrosinase belongs to the glycoside hydrolase family 1 and has up to 76% sequence similarity to other β-glucosidases. Phylogenetic analyses suggest species-specific diversification of this gene family in insects and an independent evolution of the beetle myrosinase from other insect β-glucosidases. convergent evolution | host plant specialization P hytophagous insects are confronted with an arsenal of constitutive and inducible chemical plant defenses (1). To avoid deleterious effects from plant toxins, herbivores require appropriate biochemical adaptations allowing them to deal with these metabolites, for example, by developing insensitive target sites or by enzymatic detoxification. Many specialized insects are able to sequester plant defense compounds and exploit them for their own protection against natural enemies and/or as semiochemicals in interspecific communication (2, 3).The glucosinolate-myrosinase system characteristic of plants in the order Brassicales is one of the best-studied activated plant defense systems (4-6), and several different strategies for avoiding glucosinolate toxicity have been described in specialized insect herbivores of the orders Lepidoptera, Hemiptera, and Hymenoptera (7). Glucosinolates are a structurally diverse group of β-thioglucoside-N-hydroxysulfates that are classified according to their precursor amino acid as aliphatic, aromatic, or indolic glucosinolates (6,8). Plant myrosinases, ascorbate-dependent β-thioglucosidases (EC 3.2.1.147) belonging to glycoside hydrolase family 1 (GH1), are stored separately from the glucosinolates and only come into contact with their substrate when the spatial compartmentalization is destroyed, for example, by herbivore feeding (6). The profile of hydrolysis products then depends on glucosinolate structure, cellular conditio...

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Section: Discussionmentioning

confidence: 98%

Phyllotreta striolataflea beetles use host plant defense compounds to create their own glucosinolate-myrosinase system

Beran¹,

Pauchet²,

Kunert

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

112

143

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“…10,22 Many variations of amino acid residues occur with different GH1 members, but their very similar activesite structures (see Figure 1) ensure that their analogous residues will have most of the same interactions. In general, those glycon glycosyl ligands that are free to take up different ring conformations on binding in active sites of GH members are found as relaxed 4 C 1 conformers, [23][24][25][26][27] dhurrin (CAS 499-20-7) in S. bicolor cyanogenic b-glucosidase being an exception, its glucosyl glycon taking up the 1 S 3 conformation. 10 However, glycons with half-chair conformations designed as transition-state analogs are strong inhibitors.…”

Section: Active-site Structurementioning

confidence: 99%

Computational analysis of glycoside hydrolase family 1 specificities

Hill

Reilly

2008

Biopolymers

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Glycoside hydrolase family 1 consists of beta-glucosidases, beta-galactosidases, 6-phospho-beta-galactosidases, myrosinases, and other enzymes having similar primary and tertiary structures but diverse specificities. Among these enzymes, beta-glucosidases hydrolyze cellobiose to glucose, and therefore they are key players in any cellulose to glucose process. All family members attack beta-glycosidic bonds between a pyranosyl glycon and an aglycon, but most have little specificity for the aglycon or for the bond configuration. Furthermore, glycon specificity is not absolute. Sixteen family members (six beta-glucosidases, two cyanogenic beta-glucosidases, one 6-phospho-beta-galactosidase, two myrosinases, and five beta-glycosidases) have known tertiary structures. We have used automated docking to computationally bind disaccharides with allopyranosyl, galactopyranosyl, glucopyranosyl, mannopyranosyl, 6-phosphogalactopyranosyl, and 6-phosphoglucopyranosyl glycons, all linked by beta-(1,2), beta-(1,3), beta-(1,4), and beta-(1,6)-glycosidic bonds to beta-glucopyranoside aglycons, along with beta-(1,1-thio)-allopyranosyl, -galactopyranosyl, -glucopyranosyl, and -mannopyranosyl) beta-glucopyranosides, into all of these structures to investigate the structural determinants of their enzyme specificities. The following are the eight active-site residues: Glu191, Thr194, Phe205, Asn285, Arg336, Asn376, Trp378, and Trp465 (Zea mays beta-glucosidase numbering), that control a significant amount of glycon specificity.

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“…Myrosinase enzyme from the cabbage aphid, B. brassicae, has recently been purified and partially characterized ( Jones et al 2001). The aphid enzyme is capable of hydrolysing a number of common plant glucosinolates including sinigrin (2-propenyl glucosinolate) and glucotropaeolin (benzylglucosinolate; Francis et al 2002;Jones et al 2002), and a dual function for aphid myrosinase as an oxidase and thioglucosidase has been proposed ( Francis et al 2002), although this claim requires more rigorous proof.…”

Section: Introductionmentioning

confidence: 99%

The cabbage aphid: a walking mustard oil bomb

et al. 2007

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The cabbage aphid, Brevicoryne brassicae, has developed a chemical defence system that exploits and mimics that of its host plants, involving sequestration of the major plant secondary metabolites (glucosinolates). Like its host plants, the aphid produces a myrosinase (b-thioglucoside glucohydrolase) to catalyse the hydrolysis of glucosinolates, yielding biologically active products. Here, we demonstrate that aphid myrosinase expression in head/thoracic muscle starts during embryonic development and protein levels continue to accumulate after the nymphs are born. However, aphids are entirely dependent on the host plant for the glucosinolate substrate, which they store in the haemolymph. Uptake of a glucosinolate (sinigrin) was investigated when aphids fed on plants or an in vitro system and followed a different developmental pattern in winged and wingless aphid morphs. In nymphs of the wingless aphid morph, glucosinolate level continued to increase throughout the development to the adult stage, but the quantity in nymphs of the winged form peaked before eclosion (at day 7) and subsequently declined. Winged aphids excreted significantly higher amounts of glucosinolate in the honeydew when compared with wingless aphids, suggesting regulated transport across the gut. The higher level of sinigrin in wingless aphids had a significant negative impact on survival of a ladybird predator. Larvae of Adalia bipunctata were unable to survive when fed adult wingless aphids from a 1% sinigrin diet, but survived successfully when fed aphids from a glucosinolate-free diet (wingless or winged), or winged aphids from 1% sinigrin. The apparent lack of an effective chemical defence system in adult winged aphids possibly reflects their energetic investment in flight as an alternative predator avoidance mechanism.

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Characterisation of aphid myrosinase and degradation studies of glucosinolates

Cited by 57 publications

References 39 publications

Phyllotreta striolataflea beetles use host plant defense compounds to create their own glucosinolate-myrosinase system

Phyllotreta striolataflea beetles use host plant defense compounds to create their own glucosinolate-myrosinase system

Computational analysis of glycoside hydrolase family 1 specificities

The cabbage aphid: a walking mustard oil bomb

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