Issue Date: April 18, 2016
Fungi make isoquinolines
By peering at a mysterious biosynthetic gene cluster in the common compost heap fungus Aspergillus fumigatus, a team of researchers led by Cornell University’s Frank C. Schroeder and Nancy P. Keller of the University of Wisconsin, Madison, has discovered that the microorganism unexpectedly makes a variety of isoquinolines. Scientists long thought that these natural products—based on a heterocyclic scaffold composed of a benzene ring fused to a pyridine ring—were produced primarily by plants. Isoquinolines are incredibly useful scaffolds: Members of the family are used as anesthetics, vasodilators, antifungal agents, and disinfectants. Researchers may want to mine other fungi—many of which also possess similar biosynthetic gene clusters as the one in A. fumigatus—for new, potentially useful isoquinolines or harness fungi to produce existing ones. The team found that the isoquinolines—called fumisoquin A, B, and C—made by A. fumigatus were synthesized from the amino acid tyrosine, through a sequence of phenol hydroxylation, N-methylation, and oxidative cyclization steps reminiscent of plant isoquinoline biosynthesis (Nat. Chem. Biol. 2016, DOI: 10.1038/nchembio.2061). However, the plant and fungal biosynthetic genes show no homology, suggesting that the ability to make these compounds evolved independently, yet settled on the same synthetic strategy—an example of convergent evolution.
- Chemical & Engineering News
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