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Tandem intermolecular [4 + 2] cycloadditions are catalysed by glycosylated enzymes for natural product biosynthesis
Tandem Diels-Alder reactions are frequently used in the construction of polycyclic ring systems in complex organic compounds. Unlike the many Diels-Alderases (DAases) that catalyse a single cycloaddition, enzymes for multiple Diels-Alder reactions are rare. Here we demonstrate that two calcium-ion-d...
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Published in: | Nature chemistry 2023-08, Vol.15 (8), p.1083-1090 |
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Main Authors: | , , , , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Tandem Diels-Alder reactions are frequently used in the construction of polycyclic ring systems in complex organic compounds. Unlike the many Diels-Alderases (DAases) that catalyse a single cycloaddition, enzymes for multiple Diels-Alder reactions are rare. Here we demonstrate that two calcium-ion-dependent glycosylated enzymes, EupfF and PycR1, independently catalyse sequential, intermolecular Diels-Alder reactions in the biosynthesis of bistropolone-sesquiterpenes. We elucidate the origins of catalysis and stereoselectivity within these DAases through analysis of enzyme co-crystal structures, together with computational and mutational studies. These enzymes are secreted as glycoproteins with diverse N-glycans. The N-glycan at N211 in PycR1 significantly increases the affinity to the calcium ion, which in turn regulates the active cavity, making it specifically interact with substrates to accelerate the tandem [4 + 2] cycloaddition. The synergistic effect of the calcium ion and N-glycan on the catalytic centre of enzymes involved in secondary metabolism, especially for complex tandem reactions, can extend our understanding of protein evolution and improve the artificial design of biocatalysts. |
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ISSN: | 1755-4330 1755-4349 |
DOI: | 10.1038/s41557-023-01260-8 |