Potential for interdependent development of tRNA determinants for aminoacylation and ribosome decoding

Area of Science:

• Molecular Biology
• Biochemistry
• Genetics

Background:

• Aminoacylation of transfer RNA (tRNA) by aminoacyl-tRNA synthetases is crucial for protein synthesis.
• A cross-species barrier exists, preventing bacterial aminoacyl-tRNA synthetases from acylating eukaryotic tRNA.

Purpose of the Study:

• To investigate the role of eukaryote-specific domains in overcoming the cross-species aminoacylation barrier.
• To determine if these domains can confer specificity for eukaryotic tRNA substrates onto bacterial synthetases.

Main Methods:

• Construction of a fusion protein combining Escherichia coli CysRS with a human CysRS eukaryote-specific domain.
• Testing the aminoacylation activity of the fusion protein on human tRNA(Cys).
• Assessing the impact of the A37G transition in tRNA(Cys) on aminoacylation and codon recognition.

Main Results:

• The fusion protein successfully acylated human tRNA(Cys), overcoming the cross-species barrier.
• The eukaryote-specific domain redirected the specificity of E. coli CysRS from A37 to G37.
• The A37G transition in tRNA(Cys) significantly affected codon recognition accuracy on the ribosome.

Conclusions:

• Eukaryote-specific domains are essential for bacterial aminoacyl-tRNA synthetases to acylate eukaryotic tRNA.
• These domains play a dual role in recognizing tRNA differences and altering enzyme specificity.
• tRNA nucleotide determinants for aminoacylation and ribosome decoding may be interdependent.