Structural basis of ribosomal peptide macrocyclization in plants
- The University of Western Australia, Australia
- University of Minnesota, United States
Abstract
Constrained, cyclic peptides encoded by plant genes represent a new generation of drug leads. Evolution has repeatedly recruited the Cys-protease asparaginyl endopeptidase (AEP) to perform their head-to-tail ligation. These macrocyclization reactions use the substrates amino terminus instead of water to deacylate, so a peptide bond is formed. How solvent-exposed plant AEPs macrocyclize is poorly understood. Here we present the crystal structure of an active plant AEP from the common sunflower, Helianthus annuus. The active site contained electron density for a tetrahedral intermediate with partial occupancy that predicted a binding mode for peptide macrocyclization. By substituting catalytic residues we could alter the ratio of cyclic to acyclic products. Moreover, we showed AEPs from other species lacking cyclic peptides can perform macrocyclization under favorable pH conditions. This structural characterization of AEP presents a logical framework for engineering superior enzymes that generate macrocyclic peptide drug leads.
Data availability
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Asparaginyl endopeptidase 1 bound to AAN peptide, a tetrahedral intermediateAvailable at Protein Data Bank under accession code number 6AZT.
Article and author information
Author details
Funding
Australian Research Council (FT120100013)
- Joshua S Mylne
Australian Research Council (DP160100107)
- Joshua S Mylne
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2018, Haywood et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Structural basis of ribosomal peptide macrocyclization in plants
eLife 7:e32955.
https://doi.org/10.7554/eLife.32955
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