An N-acetylated daropeptide modulates nematode development

Area of Science:

• Microbiology
• Natural Product Chemistry
• Biochemistry

Background:

• The symbiotic bacterium Photorhabdus produces bioactive secondary metabolites crucial for host interactions.
• Ribosomally synthesized natural products from Photorhabdus remain largely unexplored.
• Understanding these compounds is key to deciphering tripartite interactions involving nematodes and insects.

Purpose of the Study:

• To identify and characterize novel ribosomally synthesized natural products from Photorhabdus asymbiotica.
• To investigate the biosynthesis, structure, and function of a newly discovered darobactin-like peptide.
• To explore the ecological role of this peptide in nematode development and reproduction.

Main Methods:

• Isolation and structural elucidation of aphotorhaptin A using spectroscopic techniques.
• Biosynthetic studies to uncover the maturation pathway, including leader cleavage and N-terminal acetylation.
• Biochemical and structural analyses of the acetyltransferase PasC.
• Functional assays to assess aphotorhaptin A's activity on nematode development.

Main Results:

• Identification of aphotorhaptin A, a hexapeptide featuring an ether crosslink and N-terminal acetylation.
• Elucidation of an unusual leader cleavage and N-terminal acetylation mechanism mediated by PasC.
• PasC demonstrated broad substrate promiscuity due to its large active-site cavity.
• Aphotorhaptin A modulates nematode development, requiring specific structural features for activity, but lacks antibacterial properties.

Conclusions:

• Aphotorhaptin A expands the known chemical diversity of ribosomal peptides.
• The study reveals novel insights into the biosynthesis and functional roles of Photorhabdus natural products.
• This peptide's activity highlights a direct link between bacterial metabolites and nematode development, impacting ecological interactions.