Structural highlights
FunctionPublication Abstract from PubMedThe ribosomally synthesized and post-translationally modified peptide (RiPP) superfamily of natural products includes many examples of cyclic peptides with diverse macrocyclization chemistries. The graspetides, one family of macrocyclized RiPPs, harbor side chain-side chain ester or amide linkages. We recently reported the structure and biosynthesis of the graspetide pre-fuscimiditide, a 22-amino-acid (aa) peptide with two ester cross-links forming a stem-loop structure. These cross-links are introduced by a single graspetide synthetase, the ATP-grasp enzyme ThfB. Here we show that ThfB can also catalyze the formation of amide or thioester cross-links in prefuscimiditide, with thioester formation being especially efficient. We further show that upon proteolysis to reveal an N-terminal cysteine residue, the thioester-linked peptide rapidly and quantitatively rearranges via native chemical ligation into an isopeptide-bonded head-to-tail cyclic peptide. The solution structure of this rearranged peptide was determined by using 2D NMR spectroscopy experiments. Our methodology offers a straightforward recombinant route to head-to-tail cyclic peptides. Cyclic Peptides from Graspetide Biosynthesis and Native Chemical Ligation.,Choi B, Acuna A, Link AJ J Am Chem Soc. 2024 May 1;146(17):11605-11609. doi: 10.1021/jacs.4c02745. Epub , 2024 Apr 18. PMID:38634647[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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