The proline-rich antimicrobial peptide Onc112 inhibits translation by blocking and destabilizing the initiation...

Area of Science:

• Microbiology
• Structural Biology
• Drug Discovery

Background:

• Multidrug-resistant bacteria pose a significant global health threat, rendering current antibiotics ineffective.
• Proline-rich antimicrobial peptides (PrAMPs), particularly the oncocin family, show potential against Gram-negative pathogens.
• The precise mechanism by which oncocin PrAMPs inhibit bacterial translation remains largely unknown.

Purpose of the Study:

• To elucidate the molecular mechanism of action for the oncocin family PrAMP, Onc112.
• To determine the structural basis of Onc112 interaction with the bacterial ribosome.
• To provide a foundation for developing novel antibiotics targeting bacterial translation.

Main Methods:

• X-ray crystallography was employed to determine the structure of the Onc112 peptide bound to the Thermus thermophilus 70S ribosome at 3.1 Å resolution.
• Biochemical assays were conducted to investigate the functional consequences of Onc112 binding to the ribosome.

Main Results:

• The crystal structure revealed Onc112 binding within the ribosomal exit tunnel, near the peptidyl transferase center.
• Onc112 binding was found to overlap with the aminoacyl-tRNA binding site.
• Biochemical data demonstrated that Onc112 binding inhibits and destabilizes the ribosomal initiation complex, preventing elongation.

Conclusions:

• Onc112 acts by directly interfering with the ribosome's function, specifically blocking translation initiation.
• The structural and biochemical insights gained provide a rational basis for designing new PrAMP-based antibiotics.
• This research opens avenues for developing novel therapeutics against multidrug-resistant bacterial infections.