Widespread microbial utilization of ribosomal β-amino acid-containing peptides and proteins

beta- Amino residues are regarded as extremely rare features among ribosomal products. They can be installed by a remarkable non-canonical enzymatic splicing process occurring in some Nif11-type ribosomally synthesized and posttranslationally modified peptide (RiPP) pathways from select cyanobacteria. The functions of the final pathway products remained unknown. Here, a global bioinformatic analysis suggested an unexpectedly broad distribution of ribosomal beta- amino acid products in diverse bacterial lineages as well as archaea. Characterization of 27 bacterial splicease-substrate pairs confirmed the modification in all cases. The spliceotide'' products include many previously unrecognized RiPP types as well as proteins, contain 35 to >600 residues, and feature single to multiple alpha-keto-beta-amino acid moieties, with 15 different naturally occurring b units characterized and 20 predicted. Of three tested spliceotides, all exhibited exceptionally potent protease inhibitory activity, providing a potential rationale for the widespread splicease chemistry in prokaryotes and highlighting substantial potential for drug discovery and gene-based biomolecule diversification.

Automated summary

Ribosomal beta-amino acid products are considered rare features in ribosomal products and can be introduced through non-canonical enzymatic splicing. A global bioinformatic analysis revealed the widespread presence of this modification in different bacterial lineages and archaea. The tested products showed potent protease inhibitory activity, highlighting their potential in drug discovery and gene-based biomolecule diversification.