8bxl
Patulin Synthase from Penicillium expansum
Structural highlights
FunctionPATE_PENEN Patulin synthase; part of the gene cluster that mediates the biosynthesis of patulin, an acetate-derived tetraketide mycotoxin produced by several fungal species that shows antimicrobial properties against several bacteria (PubMed:25625822, PubMed:30100914, PubMed:30680886). PatE catalyzes the last step of the pathway which is the conversion of E-ascladiol to patulin (PubMed:30680886). The pathway begins with the synthesis of 6-methylsalicylic acid by the polyketide synthase (PKS) patK via condensation of acetate and malonate units. The 6-methylsalicylic acid decarboxylase patG then catalyzes the decarboxylation of 6-methylsalicylic acid to yield m-cresol (also known as 3-methylphenol). These first reactions occur in the cytosol. The intermediate m-cresol is then transported into the endoplasmic reticulum where the cytochrome P450 monooxygenase patH converts it to m-hydroxybenzyl alcohol, which is further converted to gentisyl alcohol by the cytochrome P450 monooxygenase patI. The oxidoreductases patJ and patO further convert gentisyl alcohol to isoepoxydon in the vacuole. PatN catalyzes then the transformation of isoepoxydon into phyllostine. The cluster protein patF is responsible for the conversion from phyllostine to neopatulin whereas the alcohol dehydrogenase patD converts neopatulin to E-ascladiol. The steps between isoepoxydon and E-ascladiol occur in the cytosol, and E-ascladiol is probably secreted to the extracellular space by one of the cluster-specific transporters patC or patM. Finally, the secreted patulin synthase patE catalyzes the conversion of E-ascladiol to patulin (Probable) (PubMed:30680886).[1] [2] [3] [4] Publication Abstract from PubMedPatulin synthase (PatE) from Penicillium expansum is a flavin-dependent enzyme that catalyses the last step in the biosynthesis of the mycotoxin patulin. This secondary metabolite is often present in fruit and fruit-derived products, causing postharvest losses. The patE gene was expressed in Aspergillus niger allowing purification and characterization of PatE. This confirmed that PatE is active not only on the proposed patulin precursor ascladiol but also on several aromatic alcohols including 5-hydroxymethylfurfural. By elucidating its crystal structure, details on its catalytic mechanism were revealed. Several aspects of the active site architecture are reminiscent of that of fungal aryl-alcohol oxidases. Yet, PatE is most efficient with ascladiol as substrate confirming its dedicated role in biosynthesis of patulin. Structure elucidation and characterization of patulin synthase, insights into the formation of a fungal mycotoxin.,Tjallinks G, Boverio A, Maric I, Rozeboom H, Arentshorst M, Visser J, Ram AFJ, Mattevi A, Fraaije MW FEBS J. 2023 Nov;290(21):5114-5126. doi: 10.1111/febs.16804. Epub 2023 Jun 27. PMID:37366079[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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