Fluorescently labeled ribosomes as a tool for analyzing antibiotic binding

Area of Science:

• Biochemistry
• Molecular Biology
• Pharmacology

Background:

• Studying small molecule binding to large macromolecular complexes like ribosomes is challenging.
• Existing methods for measuring ligand-ribosome interactions can be complex and time-consuming.

Purpose of the Study:

• To develop a general and sensitive method for studying the binding of small ligands to ribosomes.
• To validate the method using fluorescently labeled ribosomal protein S12 and known antibiotics.

Main Methods:

• Reconstitution of small ribosomal subunits using native 16S rRNA, purified proteins, and site-specifically fluorescently labeled ribosomal protein S12.
• Utilizing environment-sensitive fluorescent probes attached to ribosomal protein S12.
• Measuring changes in fluorescence characteristics upon antibiotic binding using a conventional fluorometer.

Main Results:

• Fluorescence of labeled ribosomal subunits was sensitive to antibiotics like streptomycin and neomycin, which bind near protein S12.
• Equilibrium dissociation constants determined by this method agreed well with previously published data and radiolabeling assays.
• The method demonstrated sensitivity and accuracy in characterizing drug-ribosome interactions.

Conclusions:

• A novel, rapid, and sensitive fluorescent labeling method enables accurate measurement of small ligand binding to ribosomes.
• This technique facilitates the determination of thermodynamic and kinetic binding parameters.
• The method is adaptable for high-throughput screening assays for antibiotic discovery.