Structural basis for translation inhibition by the glycosylated drosocin peptide

Area of Science:

• Microbiology
• Structural Biology
• Biochemistry

Background:

• Proline-rich antimicrobial peptides (PrAMPs) are crucial for innate immunity in Drosophila.
• Drosocin, a PrAMP, possesses unique O-glycosylation at threonine 11, enhancing its antimicrobial potency.
• The precise mechanism of drosocin's action, particularly the role of glycosylation, remains incompletely understood.

Purpose of the Study:

• To elucidate the structural basis of drosocin's interaction with its intracellular target, the ribosome.
• To investigate the impact of O-glycosylation on drosocin's cellular uptake and ribosomal binding.
• To provide insights into the mechanism of translation termination inhibition by glycosylated drosocin.

Main Methods:

• Cryogenic electron microscopy (Cryo-EM) at 2.0-2.8-Å resolution.
• Structural analysis of glycosylated drosocin bound to the ribosome.
• Biochemical assays to assess peptide-ribosome interactions.

Main Results:

• Cryo-EM structures reveal drosocin binding within the ribosome's polypeptide exit tunnel.
• Glycosylated drosocin traps translation release factor RF1 on the ribosome, inhibiting translation termination.
• O-glycosylation facilitates specific interactions with 23S rRNA, inducing conformational changes and disrupting base pairing.

Conclusions:

• O-glycosylated drosocin inhibits bacterial translation by interfering with termination.
• The glycosylation is critical for drosocin's ribosomal interaction and antimicrobial activity.
• This study provides a structural foundation for designing novel glycosylated antimicrobial peptides.