Detoxification of L-canavanine by the tobacco budworm, Heliothis virescens [Noctuidae]

Berge, Milan A.; Rosenthal, Gerald A.

doi:10.1021/jf00101a013

Cited by 5 publications

(6 citation statements)

References 20 publications

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“…* The T. H. Morgan School of Biological Sciences. (11). Our results demonstrate that no more than 9% of the administered canavanine is catabolized to canaline and [14C]urea (11).…”

Section: Introductionmentioning

confidence: 69%

“…(11). Our results demonstrate that no more than 9% of the administered canavanine is catabolized to canaline and [14C]urea (11). On the other hand, this insect converts about 70% of the administered L-[guaradircoory-14C]canavanine to [14C]guanidine (11).…”

Section: Introductionmentioning

confidence: 74%

“…Analysis of the me-tabolism of L-[guanidinooxy-14C]canavanine disclosed that guanidine was the principal radiolabeled reaction product. No [ 14C] hydroxyguanidine was found in L-[guanidinooxy-14C ] canavanine-treated larvae (11).…”

Section: Resultsmentioning

confidence: 98%

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Metabolism of L-canavanine and L-canaline in the tobacco budworm, Heliothis virescens [Noctuidae]

Berge

Rosenthal²

1991

Chem. Res. Toxicol.

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The metabolism of L-canavanine and L-canaline were investigated in larvae of the tobacco budworm, Heliothis virescens [Noctuidae]. H. virescens larvae were treated with L-[1,2,3,4-14C]canavanine or L-[U-14C]canaline with sufficient cold carrier to provide 5 mg g-1 canavanine or a molar equivalent of canaline (3.81 mg g-1). The preponderant catabolite in both canavanine- and canaline-treated larvae was [14C]homoserine. Other minor metabolites derived from canavanine included [14C]aspartate/asparagine, [14C]glutamate/glutamine, [14C]2-aminobutyrate, [14C]ornithine, [14C]proline, and [14C]isoleucine. Canaline yielded [14C]glutamate/glutamine, [14C]aspartate/asparagine, and [14C]-2-aminobutyrate. Our current studies support the belief that this destructive insect tolerates L-canavanine and L-canaline because of its ability to reductively cleave these potentially insecticidal natural products to L-homoserine and guanidine or ammonia, respectively.

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“…* The T. H. Morgan School of Biological Sciences. (11). Our results demonstrate that no more than 9% of the administered canavanine is catabolized to canaline and [14C]urea (11).…”

Section: Introductionmentioning

confidence: 69%

Section: Introductionmentioning

confidence: 74%

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Metabolism of L-canavanine and L-canaline in the tobacco budworm, Heliothis virescens [Noctuidae]

Berge

Rosenthal²

1991

Chem. Res. Toxicol.

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“…These studies established that H. virescens actively metabolizes canavanine under the control of a constitutive enzyme that has been isolated from the larval gut (8). Administration of L-[guanidinooxy- 14 C]canavanine to fifth instar H. virescens larvae disclosed that [ 14 C]guanidine was the principal in vivo larval radiolabeled canavanine catabolite (9).…”

mentioning

confidence: 99%

“…In contrast, tobacco hornworm larvae, Manduca sexta, maintained on a 2.5 mM canavanine-containing diet develop massive developmental aberrations (1,2). The appreciable natural resistance of H. virescens to this protective allelochemical instigated earlier studies to elucidate the biochemical basis for canavanine tolerance by H. virescens (7)(8)(9).…”

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confidence: 99%

The biochemical basis for l -canavanine tolerance by the tobacco budworm Heliothis virescens (Noctuidae)

Melangeli

Rosenthal

Dalman

1997

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

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The tobacco budworm, Heliothis virescens (Noctuidae), a destructive insect pest, is remarkably resistant to L-canavanine, L-2-amino-4-(guanidinooxy)butyric acid, an arginine antimetabolite that is a potent insecticide for nonadapted species. H. virescens employs a constitutive enzyme of the larval gut, known trivially as canavanine hydrolase (CH), to catalyze an irreversible hydrolysis of L-canavanine to L-homoserine and hydroxyguanidine. As such, it represents a new type of hydrolase, one acting on oxygen-nitrogen bonds (EC 3.13.1.1). This enzyme has been isolated from the excised gut of H. virescens and purified to homogeneity; it exhibits an apparent K m value for L-canavanine of 1.1 mM and a turnover number of 21.1 mol⅐min ؊1 ⅐mol ؊1 . This enzyme has a mass of 285 kDa and is composed of two subunits with a mass of 50 kDa or 47.5 kDa. CH has a high degree of specificity for L-canavanine as it cannot function effectively with either L-2-amino-5-(guanidinooxy)pentanoate or L-2-amino-3-(guanidinooxy)propionate, the higher or lower homolog of L-canavanine, respectively. L-Canavanine derivatives such as methyl-L-canavanine, or L-canaline and O-ureido-L-homoserine, are not metabolized significantly by CH.

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l -Canavanine: a higher plant insecticidal allelochemical

Rosenthal¹

2001

Amino Acids

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L-Canavanine, L-2-amino-4-(guanidinooxy)butyric acid, is a potentially toxic nonprotein amino acid of certain leguminous plants. Many species are prolific canavanine producers; they divert enormous nitrogen resource to the storage of this single natural product. Canavanine, a highly effective protective allelochemical, provides a formidable chemical barrier to predation and disease. The accumulated experimental evidence leaves little doubt that the key element in the ability of canavanine to function as an effective protective allelochemical is its subtle structural mimicry of arginine which makes it an effective substrate for amino acid activation and aminoacylation, and its marked diminution in basicity relative to arginine which mediates the production of structural aberrant, dysfunctional canavanyl proteins. The biological burdens of canavanyl protein formation by canavanine-treated Manduca sexta larvae were carried throughout their remaining life cycle. Protein-based sequestration of canavanine prevented turnover and clearance of the free amino acid, and undoubtedly contributed significantly to the antimetabolic character of this protective allelochemical.

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Detoxification of L-canavanine by the tobacco budworm, Heliothis virescens [Noctuidae]

Cited by 5 publications

References 20 publications

Metabolism of L-canavanine and L-canaline in the tobacco budworm, Heliothis virescens [Noctuidae]

Metabolism of L-canavanine and L-canaline in the tobacco budworm, Heliothis virescens [Noctuidae]

The biochemical basis for l -canavanine tolerance by the tobacco budworm Heliothis virescens (Noctuidae)

l -Canavanine: a higher plant insecticidal allelochemical

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