Identification of amino acid networks governing catalysis in the closed complex of class I terpene synthases

Class I terpene synthases generate the structural core of bioactive terpenoids. Deciphering structure–function relationships in the reactive closed complex and targeted engineering is hampered by highly dynamic carbocation rearrangements during catalysis. Available crystal structures, however, repre...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2016-02, Vol.113 (8), p.E958-E967
Main Authors: Schrepfer, Patrick, Buettner, Alexander, Goerner, Christian, Hertel, Michael, van Rijn, Jeaphianne, Wallrapp, Frank, Eisenreich, Wolfgang, Sieber, Volker, Kourist, Robert, Brück, Thomas
Format: Article
Language:English
Subjects:
Alkyl and Aryl Transferases - chemistry
Amino Acid Motifs
Amino acids
Biological Sciences
Catalysis
Catalytic Domain
Crystal structure
Models, Molecular
PNAS Plus
Proteins
Sequence Analysis, Protein - methods
Substrates
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Summary:Class I terpene synthases generate the structural core of bioactive terpenoids. Deciphering structure–function relationships in the reactive closed complex and targeted engineering is hampered by highly dynamic carbocation rearrangements during catalysis. Available crystal structures, however, represent the open, catalytically inactive form or harbor nonproductive substrate analogs. Here, we present a catalytically relevant, closed conformation of taxadiene synthase (TXS), the model class I terpene synthase, which simulates the initial catalytic time point. In silico modeling of subsequent catalytic steps allowed unprecedented insights into the dynamic reaction cascades and promiscuity mechanisms of class I terpene synthases. This generally applicable methodology enables the active-site localization of carbocations and demonstrates the presence of an active-site base motif and its dominating role during catalysis. It additionally allowed in silico-designed targeted protein engineering that unlocked the path to alternate monocyclic and bicyclic synthons representing the basis of a myriad of bioactive terpenoids.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.1519680113