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Abstract
Covering: 2016 to 2023Ribosomally synthesized and posttranslationally modified peptides (RiPPs) continue to be a rich source of chemically diverse and bioactive peptide natural products. In recent years, cyclophane-containing RiPP natural products and their biosynthetic pathways have been more frequently encountered. This highlight will focus on bacterial monoaryl cyclophane-containing RiPPs. This class of RiPPs is produced by radical SAM/SPASM enzymes that form a crosslink between the aromatic ring and sidechain of two amino acid residues of the precursor peptide. Selected natural products from these pathways exhibit specific antibacterial activity against gram-negative pathogens. The approaches used to discover these pathways and products will be described and categorized as natural product-first or enzyme-first. The breadth of ring systems formed by the enzymes, enzyme mechanism, and recent reports of synthetic methods for constructing these ring systems will also be presented. Bacterial cyclophane-containing RiPPs and their biosynthetic enzymes represent an untapped source of scaffolds for drug discovery and tools for synthetic biology.
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Affiliation(s)
- Chin-Soon Phan
- Department of Pharmacy, National University of Singapore, 4 Science Dr 2, Singapore 117544, Singapore.
| | - Brandon I Morinaka
- Department of Pharmacy, National University of Singapore, 4 Science Dr 2, Singapore 117544, Singapore.
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Keyes ED, Mifflin MC, Austin MJ, Alvey BJ, Lovely LH, Smith A, Rose TE, Buck-Koehntop BA, Motwani J, Roberts AG. Chemoselective, Oxidation-Induced Macrocyclization of Tyrosine-Containing Peptides. J Am Chem Soc 2023; 145:10071-10081. [PMID: 37119237 DOI: 10.1021/jacs.3c00210] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Abstract
Inspired by nature's wide range of oxidation-induced modifications to install cross-links and cycles at tyrosine (Tyr) and other phenol-containing residue side chains, we report a Tyr-selective strategy for the preparation of Tyr-linked cyclic peptides. This approach leverages N4-substituted 1,2,4-triazoline-3,5-diones (TADs) as azo electrophiles that react chemoselectively with the phenolic side chain of Tyr residues to form stable C-N1-linked cyclic peptides. In the developed method, a precursor 1,2,4-triazolidine-3,5-dione moiety, also known as urazole, is readily constructed at any free amine revealed on a solid-supported peptide. Once prepared, the N4-substituted urazole peptide is selectively oxidized using mild, peptide-compatible conditions to generate an electrophilic N4-substituted TAD peptide intermediate that reacts selectively under aqueous conditions with internal and terminal Tyr residues to furnish Tyr-linked cyclic peptides. The approach demonstrates good tolerance of native residue side chains and enables access to cyclic peptides ranging from 3- to 11-residues in size (16- to 38-atom-containing cycles). The identity of the installed Tyr-linkage, a stable covalent C-N1 bond, was characterized using NMR spectroscopy. Finally, we applied the developed method to prepare biologically active Tyr-linked cyclic peptides bearing the integrin-binding RGDf epitope.
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Affiliation(s)
- E Dalles Keyes
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
| | - Marcus C Mifflin
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
| | - Maxwell J Austin
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
| | - Brighton J Alvey
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
| | - Lotfa H Lovely
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
| | - Andriea Smith
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
| | - Tristin E Rose
- 1200 Pharma LLC, 6100 Bristol Parkway, Culver City, California 90230, United States
| | - Bethany A Buck-Koehntop
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
| | - Jyoti Motwani
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
| | - Andrew G Roberts
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
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