Landornamides: Antiviral Ornithine‐Containing Ribosomal Peptides Discovered through Genome Mining

• Published in: Angewandte Chemie International Edition 2020-07, Vol.59 (29), p.11763-11768
• Main Authors: Bösch, Nina M., Borsa, Mariana, Greczmiel, Ute, Morinaka, Brandon I., Gugger, Muriel, Oxenius, Annette, Vagstad, Anna L., Piel, Jörn
• Format: Article
• Language: English
• Subjects: Animals; antiviral agents; Antiviral Agents - chemical synthesis; Antiviral Agents - pharmacology; Arginase; Bacterial Proteins - chemical synthesis; Bacterial Proteins - pharmacology; biosynthesis; Cell Line; Computational Biology; Cyanobacteria; Cyanobacteria - chemistry; Cytotoxins; Data Mining; Databases, Genetic; E coli; Escherichia coli - genetics; Genomes; Life Sciences; Lymphocytic Choriomeningitis - drug therapy; Lymphocytic choriomeningitis virus; Metabolites; Mice; Multigene Family; Ornithine; Ornithine - chemistry; Peptides; Peptides - chemical synthesis; Peptides - chemistry; Peptides - pharmacology; Protein Processing, Post-Translational; Ribosomal Proteins - chemical synthesis; Ribosomal Proteins - pharmacology; Ribosomes - chemistry; RiPPs; Viruses
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201916321

Proteusins are a family of bacterial ribosomal peptides that largely remain hypothetical genome‐predicted metabolites. The only known members are the polytheonamide‐type cytotoxins, which have complex structures due to numerous unusual posttranslational modifications (PTMs). Cyanobacteria contain large numbers of putative proteusin loci. To investigate their chemical and pharmacological potential beyond polytheonamide‐type compounds, we characterized landornamide A, the product of the silent osp gene cluster from Kamptonema sp. PCC 6506. Pathway reconstruction in E. coli revealed a peptide combining lanthionines, d‐residues, and, unusually, two ornithines introduced by the arginase‐like enzyme OspR. Landornamide A inhibited lymphocytic choriomeningitis virus infection in mouse cells, thus making it one of the few known anti‐arenaviral compounds. These data support proteusins as a rich resource of chemical scaffolds, new maturation enzymes, and bioactivities. A ribosomal route to ornithine peptides: Genomic predictions in Cyanobacteria suggested untapped capacity for structurally diverse proteusin peptide natural products. Transfer of an orphan pathway into E. coli yielded landornamide A, an ornithine‐containing peptide with rare antiviral activity. Although common in non‐ribosomal peptides, ornithine is a novel post‐translational modification of arginine.