Sequence-dependent elongation dynamics on macrolide-bound ribosomes

Area of Science:

• Molecular Biology
• Microbiology
• Biochemistry

Background:

• The traditional model of macrolide antibiotics acting as simple plugs in the ribosomal nascent peptide exit tunnel (NPET) is being re-evaluated.
• Emerging evidence suggests a more complex, heterogeneous mechanism involving drug-peptide interactions.

Purpose of the Study:

• To investigate the dynamic processes of macrolide antibiotic interaction with translating ribosomes.
• To understand how drug-peptide interactions affect ribosomal elongation dynamics and the fate of protein synthesis.

Main Methods:

• Single-molecule tracking of elongating ribosomes.
• Inhibition of elongation using erythromycin with various nascent chains (ErmCL, H-NS).
• Analysis of translation dynamics and pausing events.

Main Results:

• Peptide sequence-specific alterations in translation elongation dynamics were observed with macrolide-obstructed NPET.
• Erythromycin did not generally inhibit elongation rates but caused abrupt stalls or pauses.
• Nascent chain-dependent elongation pausing pathways in the presence of macrolides influenced ribosome fate (stalling vs. readthrough).

Conclusions:

• Macrolide antibiotic action is a complex, dynamic process influenced by nascent peptide sequence.
• Drug-peptide interactions, not just physical obstruction, govern ribosome behavior during macrolide inhibition.
• This provides a new perspective on macrolide antibiotic mechanisms and resistance.