Structural basis for TetM-mediated tetracycline resistance.

Area of Science:

• Molecular Biology
• Microbiology
• Structural Biology

Background:

• Ribosome protection proteins (RPPs) confer antibiotic resistance.
• RPPs bind to ribosomes, preventing antibiotics like tetracycline from binding.
• The exact mechanism of RPPs, particularly TetM, remains incompletely understood.

Purpose of the Study:

• To elucidate the mechanism of action of TetM in conferring tetracycline resistance.
• To determine the structural basis of TetM-ribosome interaction.

Main Methods:

• Cryo-electron microscopy (cryo-EM) was used to determine the structure.
• The structure of TetM in complex with the 70S ribosome was solved at 7.2-Å resolution.

Main Results:

• The cryo-EM structure reveals direct contacts between TetM and the 70S ribosome.
• A key interaction involves TetM's C-terminal extension with the ribosome's decoding center.
• Domain IV of TetM directly interacts with the tetracycline binding site, suggesting direct drug displacement.

Conclusions:

• TetM directly dislodges tetracycline from the ribosome to confer resistance.
• This finding refines the model of RPPs' mechanism of action.
• Identified critical residues in TetM for tetracycline resistance provide insights for future drug development.