Indolylamide Macrocyclization by a Streptococcus pneumoniae ThiF-like Enzyme Family Member

Area of Science:

• Biochemistry
• Molecular Biology
• Natural Product Chemistry

Background:

• ThiF-like enzymes are crucial catalysts in various Ribosomally synthesized and Post-translationally modified peptides (RiPPs) biosynthetic pathways.
• These enzymes are known for forming specific chemical bonds, including thiolactone and phosphoramidate linkages.

Purpose of the Study:

• To explore novel chemical reactions and expand the known functional repertoire of ThiF-like enzymes.
• To identify new RiPP pathways and their associated enzymes through a comprehensive genomic analysis.

Main Methods:

• Global genome mining was employed to identify potential RiPP clusters.
• A minimal RiPP cluster, designated "ind", was identified in Streptococcus pneumoniae.
• In vitro biochemical assays were performed to characterize the function of the identified enzyme, IndF.

Main Results:

• The study identified a novel RiPP cluster in the human pathogen Streptococcus pneumoniae.
• Biochemical characterization of the enzyme IndF revealed the formation of an indolylamide (Trp-Ile) linkage.
• This represents the first instance of an indolylamide linkage in a RiPP pathway and a new catalytic activity for ThiF-like enzymes.

Conclusions:

• The discovery of IndF and its unique catalytic activity expands the known chemical space of ThiF-like enzymes.
• This finding highlights the potential for discovering new biochemical reactions within microbial genomes.
• The identified pathway in Streptococcus pneumoniae offers a new system for studying RiPP biosynthesis and enzyme function.