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First biosynthetic pathway of 1-hepten-3-one in Iporangaia pustulosa (Opiliones).

Rocha DF, Wouters FC, Machado G, Marsaioli AJ - Sci Rep (2013)

Bottom Line: Our analysis also indicates the presence of methylmalonyl-CoA mutase, converting acetate into propionyl-CoA via succinyl-CoA, together with other C₃ unit routes.This is the first biosynthetic study of alkyl vinyl ketones in arthropods.Our results shed light on the origin and diversification of chemical compounds in a major arthropod group.

View Article: PubMed Central - PubMed

Affiliation: Chemistry Institute, State University of Campinas, POB 6154, 13083-970 Campinas, SP, Brazil.

ABSTRACT
Arthropods produce a great variety of natural compounds, many of which have unexplored biosynthesis. Among the armored harvestmen (Arachnida: Opiliones) of the suborder Laniatores, the defensive gland exudates contain vinyl ketones and other constituents of supposed polyketide origin. We have studied the biosynthesis of 1-hepten-3-one in the Neotropical harvestman Iporangaia pustulosa by feeding individuals with ¹³C-labeled precursors, demonstrating its mixed acetate/propionate origin. ¹³C NMR spectroscopy showed an unusual labeling pattern suggesting different propionate sources for starting and extender units. Our analysis also indicates the presence of methylmalonyl-CoA mutase, converting acetate into propionyl-CoA via succinyl-CoA, together with other C₃ unit routes. This is the first biosynthetic study of alkyl vinyl ketones in arthropods. Our results shed light on the origin and diversification of chemical compounds in a major arthropod group.

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Labeling pattern of 1 by feeding Iporangaia pustulosa individuals with 13C labeled precursors.Colored ball indicate 13C labeled positions. Green signals means expected and magenta means unexpected labeling. The ball sizes correspond to 13C enrichment (%).
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f4: Labeling pattern of 1 by feeding Iporangaia pustulosa individuals with 13C labeled precursors.Colored ball indicate 13C labeled positions. Green signals means expected and magenta means unexpected labeling. The ball sizes correspond to 13C enrichment (%).

Mentions: A closer examination of the 13C NMR spectra from labeling experiments with [4-13C]methylmalonate, [1-13C]acetate and [1-13C]glucose revealed intriguing labeling patterns relative to the C3 units (Fig. 4). The unexpected labeling of 1 at C-6, by adding [4-13C]methylmalonate to the diet of Iporangaia individuals suggests the existence of a methylmalonyl-CoA mutase. The isotopic enhancement at positions C-6 (1.5%) and C-7 (2.3%) complies with the methylmalonyl-CoA–succinyl-CoA interconversion, leading to [2-13C] and [3-13C]propionyl-CoA biosynthesis as consequence of the equilibrium succinyl-CoA-succinate17 (Fig. 5a1). Stronger enrichment at C-7 indicates the incorporation of [3-13C]propionyl-CoA and the enrichment at C-1 (1.9%) is provided by direct incorporation of [4-13C]methylmalonyl-CoA as the second extender unit (Fig. 5c). Moreover, labeling of 1 at propionate units with [1-13C]acetate incorporation (Fig. 4) suggests the conversion of acetate into propionate/methylmalonate. The presence of methylmalonyl-CoA would yield [1-13C]methylmalonyl-CoA (Fig. 5c), undetectable due to the loss of labeled carbon, as depicted in Figure 3c. Methylmalonyl-CoA mutase was previously reported in polyketide biosynthesis of insects181920 and other arthropods21, suggesting that 1 from I. pustulosa possesses similar biosynthetic origin.


First biosynthetic pathway of 1-hepten-3-one in Iporangaia pustulosa (Opiliones).

Rocha DF, Wouters FC, Machado G, Marsaioli AJ - Sci Rep (2013)

Labeling pattern of 1 by feeding Iporangaia pustulosa individuals with 13C labeled precursors.Colored ball indicate 13C labeled positions. Green signals means expected and magenta means unexpected labeling. The ball sizes correspond to 13C enrichment (%).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3818658&req=5

f4: Labeling pattern of 1 by feeding Iporangaia pustulosa individuals with 13C labeled precursors.Colored ball indicate 13C labeled positions. Green signals means expected and magenta means unexpected labeling. The ball sizes correspond to 13C enrichment (%).
Mentions: A closer examination of the 13C NMR spectra from labeling experiments with [4-13C]methylmalonate, [1-13C]acetate and [1-13C]glucose revealed intriguing labeling patterns relative to the C3 units (Fig. 4). The unexpected labeling of 1 at C-6, by adding [4-13C]methylmalonate to the diet of Iporangaia individuals suggests the existence of a methylmalonyl-CoA mutase. The isotopic enhancement at positions C-6 (1.5%) and C-7 (2.3%) complies with the methylmalonyl-CoA–succinyl-CoA interconversion, leading to [2-13C] and [3-13C]propionyl-CoA biosynthesis as consequence of the equilibrium succinyl-CoA-succinate17 (Fig. 5a1). Stronger enrichment at C-7 indicates the incorporation of [3-13C]propionyl-CoA and the enrichment at C-1 (1.9%) is provided by direct incorporation of [4-13C]methylmalonyl-CoA as the second extender unit (Fig. 5c). Moreover, labeling of 1 at propionate units with [1-13C]acetate incorporation (Fig. 4) suggests the conversion of acetate into propionate/methylmalonate. The presence of methylmalonyl-CoA would yield [1-13C]methylmalonyl-CoA (Fig. 5c), undetectable due to the loss of labeled carbon, as depicted in Figure 3c. Methylmalonyl-CoA mutase was previously reported in polyketide biosynthesis of insects181920 and other arthropods21, suggesting that 1 from I. pustulosa possesses similar biosynthetic origin.

Bottom Line: Our analysis also indicates the presence of methylmalonyl-CoA mutase, converting acetate into propionyl-CoA via succinyl-CoA, together with other C₃ unit routes.This is the first biosynthetic study of alkyl vinyl ketones in arthropods.Our results shed light on the origin and diversification of chemical compounds in a major arthropod group.

View Article: PubMed Central - PubMed

Affiliation: Chemistry Institute, State University of Campinas, POB 6154, 13083-970 Campinas, SP, Brazil.

ABSTRACT
Arthropods produce a great variety of natural compounds, many of which have unexplored biosynthesis. Among the armored harvestmen (Arachnida: Opiliones) of the suborder Laniatores, the defensive gland exudates contain vinyl ketones and other constituents of supposed polyketide origin. We have studied the biosynthesis of 1-hepten-3-one in the Neotropical harvestman Iporangaia pustulosa by feeding individuals with ¹³C-labeled precursors, demonstrating its mixed acetate/propionate origin. ¹³C NMR spectroscopy showed an unusual labeling pattern suggesting different propionate sources for starting and extender units. Our analysis also indicates the presence of methylmalonyl-CoA mutase, converting acetate into propionyl-CoA via succinyl-CoA, together with other C₃ unit routes. This is the first biosynthetic study of alkyl vinyl ketones in arthropods. Our results shed light on the origin and diversification of chemical compounds in a major arthropod group.

Show MeSH