7LI2 image
Entry Detail
PDB ID:
7LI2
Title:
Omega ester peptide pre-fuscimiditide
Biological Source:
PDB Version:
Deposition Date:
2021-01-26
Release Date:
2022-02-09
Method Details:
Experimental Method:
Conformers Calculated:
100
Conformers Submitted:
20
Selection Criteria:
structures with the lowest energy
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Pre-fuscimiditide peptide
Chain IDs:A
Chain Length:22
Number of Molecules:1
Biological Source:Thermobifida fusca (strain YX)
Ligand Molecules
Primary Citation
Biosynthesis and characterization of fuscimiditide, an aspartimidylated graspetide.
Nat.Chem. 14 1325 1334 (2022)
PMID: 35982233 DOI: 10.1038/s41557-022-01022-y

Abstact

Microviridins and other ω-ester-linked peptides, collectively known as graspetides, are characterized by side-chain-side-chain linkages installed by ATP-grasp enzymes. Here we report the discovery of a family of graspetides, the gene clusters of which also encode an O-methyltransferase with homology to the protein repair catalyst protein L-isoaspartyl methyltransferase. Using heterologous expression, we produced fuscimiditide, a ribosomally synthesized and post-translationally modified peptide (RiPP). NMR analysis of fuscimiditide revealed that the peptide contains two ester cross-links forming a stem-loop macrocycle. Furthermore, an unusually stable aspartimide moiety is found within the loop macrocycle. We fully reconstituted fuscimiditide biosynthesis in vitro including formation of the ester and aspartimide moieties. The aspartimide moiety embedded in fuscimiditide hydrolyses regioselectively to isoaspartate. Surprisingly, this isoaspartate-containing peptide is also a substrate for the L-isoaspartyl methyltransferase homologue, thus driving any hydrolysis products back to the aspartimide form. Whereas an aspartimide is often considered a nuisance product in protein formulations, our data suggest that some RiPPs have aspartimide residues intentionally installed via enzymatic activity.

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Primary Citation of related structures