5fhi | pdb_00005fhi
Crystallographic structure of PsoE without Co
Structural highlights
FunctionPSOE_ASPFU Glutathione S-transferase; part of the gene cluster that mediates the biosynthesis of pseurotin A, a competitive inhibitor of chitin synthase and an inducer of nerve-cell proliferation (PubMed:24082142, PubMed:24939566). The PKS-NRPS hybrid synthetase psoA is responsible for the biosynthesis of azaspirene, one of the first intermediates having the 1-oxa-7-azaspiro[4,4]-non-2-ene-4,6-dione core of pseurotin, via condensation of one acetyl-CoA, 4 malonyl-CoA, and a L-phenylalanine molecule (PubMed:24082142, PubMed:24939566). The dual-functional monooxygenase/methyltransferase psoF seems to be involved in the addition of the C3 methyl group onto the pseurotin scaffold (PubMed:24939566). Azaspirene is then converted to synerazol through 4 steps including oxidation of C17 by the cytochrome P450 monooxygenase psoD, O-methylation of the hydroxy group of C8 by the methyltransferase psoC, and the trans-to-cis isomerization of the C13 olefin by the glutathione S-transferase psoE (PubMed:24939566, PubMed:27072782). The fourth step of synerazol production is performed by the dual-functional monooxygenase/methyltransferase psoF which seems to catalyze the epoxidation of the intermediate deepoxy-synerazol (PubMed:24939566). Synerazol can be attacked by a water molecule nonenzymatically at two different positions to yield two diol products, pseurotin A and pseurotin D (PubMed:24939566).[1] [2] [3] Publication Abstract from PubMedGeometric isomerization can expand the scope of biological activities of natural products. The observed chemical diversity among the pseurotin-type fungal secondary metabolites is in part generated by a trans to cis isomerization of an olefin. In vitro characterizations of pseurotin biosynthetic enzymes revealed that the glutathione S-transferase PsoE requires participation of the bifunctional C-methyltransferase/epoxidase PsoF to complete the trans to cis isomerization of the pathway intermediate presynerazol. The crystal structure of the PsoE/glutathione/presynerazol complex indicated stereospecific glutathione-presynerazol conjugate formation is the principal function of PsoE. Moreover, PsoF was identified to have an additional, unexpected oxidative isomerase activity, thus making it a trifunctional enzyme which is key to the complexity generation in pseurotin biosynthesis. Through the study, we identified a novel mechanism of accomplishing a seemingly simple trans to cis isomerization reaction. Oxidative trans to cis Isomerization of Olefins in Polyketide Biosynthesis.,Yamamoto T, Tsunematsu Y, Hara K, Suzuki T, Kishimoto S, Kawagishi H, Noguchi H, Hashimoto H, Tang Y, Hotta K, Watanabe K Angew Chem Int Ed Engl. 2016 May 17;55(21):6207-10. doi: 10.1002/anie.201600940. , Epub 2016 Apr 13. PMID:27072782[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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