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Biosynthesis of cylindrospermopsin
D L Burgoyne1, T K Hemscheidt, R E Moore
1Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii 96822, USA.
The Journal of Organic Chemistry
|May 18, 2000
Summary
Cylindrospermopsin biosynthesis involves guanidinoacetic acid as a starter unit and acetate building blocks. The origins of the starter unit and uracil ring components remain unclear in this potent cyanobacterial hepatotoxin.
Area of Science:
- Biochemistry
- Natural Product Biosynthesis
- Cyanobacterial Toxinology
Background:
- Cylindrospermopsin (1) is a potent hepatotoxin produced by the cyanobacterium Cylindrospermopsis raciborskii.
- Understanding its biosynthesis is crucial for predicting and mitigating its ecological and health impacts.
Purpose of the Study:
- To elucidate the biosynthetic pathway of cylindrospermopsin (1).
- To identify the precursor molecules and metabolic origins of key structural components of cylindrospermopsin.
Main Methods:
- Feeding experiments using isotopically labeled precursors, including guanidinoacetic acid and glycine.
- Analysis of labeled cylindrospermopsin incorporating isotopes (e.g., 13C, 15N) to trace metabolic origins.
Main Results:
- Cylindrospermopsin (1) is an acetogenin, with guanidinoacetic acid as the starter unit for the polyketide chain.
- C14 and C15 of cylindrospermopsin are derived from glycine (C1 and C2, respectively).
- C4-C13 originate from five acetate units, and the C13 methyl carbon comes from the C1 pool.
Conclusions:
- The biosynthetic pathway of cylindrospermopsin involves specific precursor incorporation and polyketide assembly.
- The formation of the guanidinoacetic acid starter unit and the uracil ring's NH-CO-NH segment does not follow known amidination pathways and requires further investigation.