Simultaneous directed assembly of three distinct heterodimeric coiled coils

Area of Science:

• Biochemistry
• Protein Engineering
• Supramolecular Chemistry

Background:

• Coiled coils are common protein structures.
• Designing specific protein assemblies is challenging.
• Understanding residue interactions is key for protein design.

Purpose of the Study:

• To investigate the simultaneous formation of multiple distinct heterodimeric coiled coils from a mixture of peptides.
• To identify the driving forces governing the selection of specific complexes among electrostatically viable options.
• To explore novel interactions for stabilizing protein structures.

Main Methods:

• Designing and synthesizing six distinct peptides.
• Analyzing the self-assembly process in solution.
• Characterizing the stability of the formed coiled coils using melting temperature (Tm) measurements.

Main Results:

• Successfully formed three distinct heterodimeric coiled coils simultaneously from a mixture of six peptides.
• Identified a novel interaction involving buried urea-terminated side chains as a key determinant for complex formation and stability.
• Observed extremely stable dimeric coiled coils with melting temperatures (Tm) ranging from 63 to 79°C.
• Demonstrated that core urea groups can form stable complexes with other polar groups like guanidines, acids, and amides.

Conclusions:

• The alignment of buried core residues, particularly novel urea-urea interactions, governs the selective formation of specific coiled coil complexes.
• Urea-terminated side chains provide a powerful strategy for creating highly stable protein structures.
• This work offers new insights into protein self-assembly and provides a versatile approach for designing complex protein architectures.