Dynamics of Recognition between tRNA and elongation factor Tu

Area of Science:

• Molecular Biology
• Biochemistry
• Structural Biology

Background:

• Elongation factor Tu (EF-Tu) is crucial for protein synthesis, binding and delivering aminoacyl-tRNAs (aa-tRNAs) to the ribosome.
• EF-Tu protects the aminoacyl ester bond and its interaction with aa-tRNAs is critical for translation fidelity.
• Understanding the biophysical basis of EF-Tu.aa-tRNA complex dynamics is key to deciphering translational regulation.

Purpose of the Study:

• To investigate the molecular dynamics of the EF-Tu.guanosine 5'-triphosphate.aa-tRNA(Cys) complex.
• To elucidate the roles of Mg2+ ions and modified nucleosides in protein-RNA binding free energy.
• To identify coevolving residues and conserved nucleotides that govern EF-Tu.aa-tRNA binding specificity.

Main Methods:

• Molecular dynamics (MD) simulations of the EF-Tu.GTP.aa-tRNA(Cys) complex.
• Energetic analysis of protein-RNA interactions, including contributions from Mg2+ ions and modified nucleosides.
• Evolutionary analysis, including coevolutionary mapping and principal components analysis (PCA).

Main Results:

• Modified nucleosides significantly impact tRNA structural dynamics and the EF-Tu.aa-tRNA interface.
• Conserved EF-Tu residues and specific tRNA nucleotides (G1, G52, G53, U54) are critical for binding affinity and specificity.
• Mutational analysis of tRNA confirmed experimental observations and predicted binding free energy changes under various conditions (misacylation, protonation states).

Conclusions:

• EF-Tu.aa-tRNA binding is finely tuned by conserved residues and specific nucleotide modifications, ensuring translational accuracy.
• The study reveals a complex interplay between protein and RNA dynamics, influenced by ions and nucleoside modifications.
• MD simulations provide insights into the molecular mechanisms underlying tRNA selection and binding by EF-Tu, with implications for understanding translation fidelity.