PDBsum entry 5n4f

Hydrolase

PDB id: 5n4f

Contents

Protein chain

703 a.a.

Ligands

GOL ×2

Waters ×187

References listed in PDB file

Key reference

• Title: Characterization of a dual function macrocyclase enables design and use of efficient macrocyclization substrates.
• Authors: C.M.Czekster, H.Ludewig, S.A.Mcmahon, J.H.Naismith.
• Ref.: Nat Commun, 2017, 8, 1045.
• PubMed id: 29051530

Abstract

Peptide macrocycles are promising therapeutic molecules because they are protease resistant, structurally rigid, membrane permeable, and capable of modulating protein-protein interactions. Here, we report the characterization of the dual function macrocyclase-peptidase enzyme involved in the biosynthesis of the highly toxic amanitin toxin family of macrocycles. The enzyme first removes 10 residues from the N-terminus of a 35-residue substrate. Conformational trapping of the 25 amino-acid peptide forces the enzyme to release this intermediate rather than proceed to macrocyclization. The enzyme rebinds the 25 amino-acid peptide in a different conformation and catalyzes macrocyclization of the N-terminal eight residues. Structures of the enzyme bound to both substrates and biophysical analysis characterize the different binding modes rationalizing the mechanism. Using these insights simpler substrates with only five C-terminal residues were designed, allowing the enzyme to be more effectively exploited in biotechnology.