A structural basis for streptomycin-induced misreading of the genetic code

Area of Science:

• Molecular Biology
• Structural Biology
• Biochemistry

Background:

• Protein synthesis relies on accurate codon-anticodon recognition by the ribosome.
• Aminoglycoside antibiotics, like streptomycin, interfere with this decoding process.
• Streptomycin binds near the ribosome's codon recognition site, impacting its function.

Purpose of the Study:

• To elucidate the structural mechanism by which streptomycin disrupts ribosomal decoding.
• To define the impact of streptomycin on the Thermus thermophilus 30S ribosomal subunit's decoding site.

Main Methods:

• X-ray crystallography was employed to visualize the ribosome's decoding site.
• Complexes of the 30S ribosomal subunit with messenger RNA and anticodon stem-loop analogues were studied.
• Structures were determined in the presence and absence of streptomycin.

Main Results:

• Streptomycin induces significant local distortions in the 16S ribosomal RNA.
• Key bases (A1492 and A1493) involved in codon recognition are affected by streptomycin.
• Streptomycin stabilizes interactions with near-cognate anticodon stem-loop analogues.
• Streptomycin destabilizes interactions with cognate anticodon stem-loop analogues.

Conclusions:

• Streptomycin disrupts accurate codon recognition by altering ribosomal RNA structure.
• The antibiotic promotes misreading by stabilizing incorrect transfer RNA binding.
• These findings explain how streptomycin causes both errors and fidelity changes in protein synthesis.