Choice of synonymous codons associated with protein folding

Area of Science:

• Molecular Biology
• Bioinformatics
• Structural Biology

Background:

• Protein three-dimensional structure determination requires information beyond primary amino acid sequences.
• Nucleic acid base composition may contain additional information relevant to protein structure and function.
• The third codon position in gene sequences is known for its degeneracy and potential role in translational efficiency.

Purpose of the Study:

• To investigate correlations between nucleic acid base composition and protein structure.
• To explore the relationship between base composition at the third codon position and protein folding kinetics.
• To identify potential biochemical rationales for synonymous codon usage in guiding protein folding.

Main Methods:

• Bioinformatical analysis of gene sequences and associated protein structures.
• Statistical analysis to identify correlations between base frequencies at the third codon position (e.g., u(3), c(3), a(3), g(3)).
• Correlation of base composition with refolding rate constants of large proteins exhibiting multistate folding.

Main Results:

• Significant inverse correlations were found between specific base pairs at the third codon position (e.g., u(3) vs. c(3), a(3) vs. g(3)).
• Positive correlations were observed between other base pairs at the third codon position (e.g., u(3) vs. a(3), c(3) vs. g(3)).
• Correlation coefficients for these relationships were strong (e.g., -0.92, -0.89, 0.83), particularly for large proteins with complex folding.

Conclusions:

• The composition of bases at the third codon position is interconnected and significantly correlates with protein folding properties.
• Synonymous codon choice, influenced by base composition, appears to play a role in guiding protein folding in vivo.
• These findings suggest an underlying biochemical rationale for codon usage bias related to protein structural dynamics.