An engineered minidomain containing an elastin turn exhibits a reversible temperature-induced IgG binding

Area of Science:

• Protein engineering
• Biochemistry
• Molecular biology

Background:

• Staphylococcal Protein A is a well-known protein with Fc-binding properties.
• Protein engineering can modify protein structure and function.
• Elastin peptides exhibit inverse temperature-induced folding.

Purpose of the Study:

• To engineer a protein A variant with an elastin sequence to create a temperature-modulated switch.
• To investigate the effect of an elastin sequence on protein A's structure and Fc-binding affinity.
• To explore the potential of elastin sequences in modifying globular protein activity.

Main Methods:

• Engineering a two-helix protein A mutant incorporating an elastin sequence (GVPGVG) into the inter-helix turn.
• Circular dichroism (CD) spectroscopy to measure helical structure and stability.
• Measurement of Fc-binding affinity at varying temperatures.

Main Results:

• Elastin mutants lost helical structure and showed reduced stability compared to wild-type protein A.
• While initial Fc-binding affinity was lower, the elastin-turn mutant exhibited a 21-fold affinity improvement over a temperature range.
• CD melting curves indicated cooperative behavior consistent with elastin peptide folding.

Conclusions:

• Short elastin sequences can modify local structure and activity when inserted into stable globular proteins.
• Elastin sequences can function as temperature-modulated switches, altering protein activity with temperature changes.
• This study demonstrates a novel approach to engineer temperature-responsive proteins.