A ribosomally synthesised and post-translationally modified peptide containing a β-enamino acid and a macrocyclic motif

Abstract

Ribosomally synthesized and post-translationally modified peptides (RiPPs) are structurally complex natural products with diverse bioactivities. Here we report discovery of a RiPP, kintamdin, for which the structure is determined through spectroscopy, spectrometry and genomic analysis to feature a bis-thioether macrocyclic ring and a β-enamino acid residue. Biosynthetic investigation demonstrated that its pathway relies on four dedicated proteins: phosphotransferase KinD, Lyase KinC, kinase homolog KinH and flavoprotein KinI, which share low homologues to enzymes known in other RiPP biosynthesis. During the posttranslational modifications, KinCD is responsible for the formation of the characteristic dehydroamino acid residues including the β-enamino acid residue, followed by oxidative decarboxylation on the C-terminal Cys and subsequent cyclization to provide the bis-thioether ring moiety mediated by coordinated action of KinH and KinI. Finally, conserved genomic investigation allows further identification of two kintamdin-like peptides among the kin-like BGCs, suggesting the occurrence of RiPPs from actinobacteria.

Dehydroamino acid residues in bioactive natural products

“…48,49 The formation of AviCys residues in 3 and 6 would actually require enzyme partners, which are likely to be inactive kinase-like proteins, to coordinate with the corresponding decarboxylases. 38,48 A similar case has also been also found in MAbi formation during the biosynthesis of 1 , where the flavoprotein KinI requires the presence of kinase-like KinH to facilitate the oxidative decarboxylation and subsequent bicyclic crosslinking in E coli gene co-expression experiments 26 (Fig. 9B).…”

Discovery and engineering of ribosomally synthesized and post-translationally modified peptide (RiPP) natural products

“…43 Through comprehensive analysis of kintamdin BGC, additional members of the previously uncharacterized b-bithionins family, sharing similarities with kintamdin, were identified through genomic analysis. 43 Marine microbes represent a significant and diverse group of organisms. 44,45 Within the marine environment, there is a Fig.…”

Cytochromes P450 involved in bacterial RiPP biosyntheses

“…The ribosomally synthesized and post-translationally modified peptides (RiPPs) are a rapidly growing class of secondary metabolites that are recognized for their structural and functional diversity (Arnison et al., 2013 ; Montalbán-López et al., 2021 ). To date, there are >40 classes of RiPPs (Hubrich et al., 2022 ; Montalbán-López et al., 2021 ; Ortiz-López et al., 2020 ; Russell et al., 2021 ; Wang et al., 2022 ). RiPPs originate from the ribosome and are present in prokaryotes (Arnison et al., 2013 ), eukaryotes (Luo & Dong, 2019 ), and archaea (Besse et al., 2015 ).…”