A Single Synonymous Variant (c.354G>A [p.P118P]) in ADAMTS13 Confers Enhanced Specific Activity

Area of Science:

• Biochemistry
• Molecular Biology
• Genetics

Background:

• Synonymous variants can affect protein expression and function.
• A specific ADAMTS13 variant (c.354G>A, p.P118P) previously showed increased ex vivo protein expression.
• ADAMTS13 is crucial for degrading von Willebrand Factor (VWF).

Purpose of the Study:

• Investigate the mechanism behind increased ADAMTS13 protein expression from the c.354G>A variant.
• Determine the variant's effect on ADAMTS13 physico-chemical properties.
• Understand how synonymous variations impact protein activity.

Main Methods:

• Cell-free translation assays to assess protein synthesis.
• Codon usage analysis to identify translation efficiency factors.
• Limited proteolysis and post-translational modification analysis to evaluate protein structure and modifications.
• Specific activity assays to measure enzymatic function.
• Modeled structural analysis to predict interaction changes.

Main Results:

• The c.354G>A variant demonstrated enhanced translation, potentially due to optimized codon usage.
• Protein conformation and post-translational modifications were largely unaffected, though new glycosylation sites were identified.
• The p.P118P variant exhibited significantly higher specific activity.
• Structural modeling suggested altered translation kinetics may influence ADAMTS13-VWF interactions.

Conclusions:

• Synonymous variants can increase protein expression through enhanced translation without major structural changes.
• The c.354G>A synonymous variant in ADAMTS13 leads to higher specific activity, impacting VWF degradation.
• This highlights a mechanism where translation efficiency, not just protein sequence or structure, dictates functional outcomes.