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Structure revision of cryptosporioptides and determination of the genetic basis for dimeric xanthone biosynthesis in fungi
Chemical Science, Volume: 10, Issue: 10, Pages: 2930 - 2939
Swansea University Author: Claudio Greco
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DOI (Published version): 10.1039/c8sc05126g
Three novel dimeric xanthones, cryptosporioptides A–C were isolated from Cryptosporiopsis sp. 8999 and their structures elucidated. Methylation of cryptosporioptide A gave a methyl ester with identical NMR data to cryptosporioptide, a compound previously reported to have been isolated from the same...
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Royal Society of Chemistry (RSC)
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Three novel dimeric xanthones, cryptosporioptides A–C were isolated from Cryptosporiopsis sp. 8999 and their structures elucidated. Methylation of cryptosporioptide A gave a methyl ester with identical NMR data to cryptosporioptide, a compound previously reported to have been isolated from the same fungus. However, HRMS analysis revealed that cryptosporioptide is a symmetrical dimer, not a monomer as previously proposed, and the revised structure was elucidated by extensive NMR analysis. The genome of Cryptosporiopsis sp. 8999 was sequenced and the dimeric xanthone (dmx) biosynthetic gene cluster responsible for the production of the cryptosporioptides was identified. Gene disruption experiments identified a gene (dmxR5) encoding a cytochrome P450 oxygenase as being responsible for the dimerisation step late in the biosynthetic pathway. Disruption of dmxR5 led to the isolation of novel monomeric xanthones. Cryptosporioptide B and C feature an unusual ethylmalonate subunit: a hrPKS and acyl CoA carboxylase are responsible for its formation. Bioinformatic analysis of the genomes of several fungi producing related xanthones, e.g. the widely occurring ergochromes, and related metabolites allows detailed annotation of the biosynthetic genes, and a rational overall biosynthetic scheme for the production of fungal dimeric xanthones to be proposed.
Faculty of Science and Engineering
We thank BBSRC (BB/J006289/1, BB/L01386X/1) and Syngenta for funding. LCMS instruments were provided by EPSRC (EP/F066104/1) and DFG (INST 187/621). 500 MHz NMR (EP/L011999/1) was provided by EPSRC.