Purification and characterization of myrosinase from the cabbage aphid (<i>Brevicoryne brassicae</i>), a brassica herbivore

Pontoppidan, Bo; Ekbom, Barbara; Eriksson, Susanna; Meijer, Johan

doi:10.1046/j.1432-1327.2001.01971.x

Cited by 55 publications

(62 citation statements)

References 33 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: 95%

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.

109

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: 95%

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.

109

143

View full text Add to dashboard Cite

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“…In comparison, benzyl glucosinolate (glucotropaeolin) has been shown to have 63.3 % of the relative activity of 62 in the presence of myrosinase isolated from Brevicoryne brassicae. [80] Given that glucosinolates 38 and 39 are both significantly larger than benzyl glucosinolate and are more likely to experience space restrictions within the enzyme active site, it is not entirely surprising that these compounds act as less A C H T U N G T R E N N U N G effective myrosinase substrates than benzyl glucosinolate in comparison with 62. This is especially evident for 39, containing the highly rigid biaryl functionality.…”

Section: Glucosinolatementioning

confidence: 99%

Identification, Synthesis, and Enzymology of Non‐natural Glucosinolate Chemopreventive Candidates

et al. 2008

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Isothiocyanates (ITCs) are one of the many classes of breakdown products of glucosinolates found in crucifers such as broccoli and are thought to be partially responsible for the reduced risk of degenerative diseases associated with the consumption of vegetables. The production of ITCs such as L-sulforaphane is dependent on the hydrolytic bioactivities of myrosinase, localized both within vegetable tissues and within flora of the human GI tract, and is associated with important cancer chemopreventive activities. We hypothesized that novel isothiocyanates with enhanced chemopreventive properties relative to L-sulforaphane could be identified and that their glucosinolate precursors could be synthesized. From a library of 30 synthetic ITCs, we identified several with bioactivities equal or superior to those of L-sulforaphane. The corresponding non-natural glucosinolate precursors to these novel ITCs were constructed and found to be substrates for myrosinase. By utilizing a novel RP-HPLC assay to monitor myrosinase-dependent hydrolysis reactions, 2,2-diphenylethyl glucosinolate and (biphenyl-2-yl)methyl glucosinolate were shown to exhibit 26.5 and 2.8 %, respectively, of the relative activity of sinigrin and produced their corresponding ITCs in varying yields. These data support the notion that non-natural glucosinolates can act as prodrugs for novel ITCs, with a mechanism of action reliant on their hydrolytic cleavage by myrosinase. Such non-natural glucosinolates may serve as very economical chemopreventive agents for individuals at risk for cancers of and around the GI tract.

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“…The enzyme is localized in the non-fl ight muscles and does not show high sequence similarity to plant myrosinases; however, a homology to plant β-glucosidases could be inferred [ 190 , 192 ] and accordingly a low O -β-glucosidase activity was demonstrated using standard substrates [ 192 ]. Expression of this myrosinase increases approximately twofold throughout the developmental stages in both wingless and winged aphid forms [ 185 ].…”

Section: Sequestrationmentioning

confidence: 99%

Metabolism of Glucosinolates and Their Hydrolysis Products in Insect Herbivores

Jeschke

Gershenzon

Vassão

2015

The Formation, Structure and Activity of Phytochemicals

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The glucosinolates produced by plants of the order Brassicales are part of a potent activated chemical defense system. These nitrogen-and sulfur-containing glucosides are hydrolyzed by myrosinases upon tissue damage, forming a toxic mixture of compounds consisting mostly of the corresponding isothiocyanates and nitriles. While humans fi nd these compounds pleasantly spicy and benefi cial to health, many of them are noxious and deterrent towards microorganisms and insect herbivores. Nonetheless, ingenious and effi cient biochemical mechanisms employed by several insect herbivores enable these to feed on glucosinolate-producing plants, circumventing the effects of these plant defenses. Here, we summarize some of the counteradaptations utilized by insects to overcome the defense imposed by these compounds and their hydrolysis products. Insects can divert hydrolysis to less toxic products or desulfate the parent glucosinolates to preclude them from being hydrolyzed by myrosinases. Once hydrolysis occurs, toxic electrophilic hydrolysis products can be conjugated to glutathione and various amino acids. Another insect strategy is the rapid sequestration of ingested glucosinolates to prevent hydrolysis and allow them to be used in their own defense.

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Purification and characterization of myrosinase from the cabbage aphid (Brevicoryne brassicae), a brassica herbivore

Cited by 55 publications

References 33 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

Identification, Synthesis, and Enzymology of Non‐natural Glucosinolate Chemopreventive Candidates

Metabolism of Glucosinolates and Their Hydrolysis Products in Insect Herbivores

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