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Publication Abstract from PubMed

Lasso peptides are a class of ribosomally-derived natural products with diverse bioactivities. The characteristic threaded lasso structure in these peptides derives from an isopeptide bond attaching the N-terminus of the peptide to an acidic sidechain. Here we describe the heterologous expression of a lasso peptide gene cluster encoding two lasso peptides, astexin-2 and astexin-3 and solve the solution structure of astexin-3. This cluster also encodes an enzyme annotated as a protease. We show that this enzyme, AtxE2, is a lasso peptide isopeptidase that specifically hydrolyzes astexins-2 and -3 converting them to linear peptides. Astexin-3 is highly thermostable and resists unthreading after extensive heat treatment. In contrast, astexin-2 unthreads upon heat treatment. AtxE2 has no activity toward unthreaded astexin-2 demonstrating that this isopeptidase must recognize a knotted structure in order to function. We also use this isopeptidase as a tool to study evolutionary relationships between lasso peptide gene clusters.

Discovery and Characterization of an Isopeptidase that Linearizes Lasso Peptides.,Maksimov MO, Link AJ J Am Chem Soc. 2013 Jul 17. PMID:23862624^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.