Interhelical E@g-N@aInteractions Modulate Coiled Coil Stability within aDe NovoSet of Orthogonal Peptide Heterodimers

Abstract

AbstractThe designability of orthogonal coiled coil (CC) dimers, which draw on well-established design rules, plays a pivotal role in fueling the development of CCs as synthetically versatile assembly-directing motifs for the fabrication of bionanomaterials. Here, we aim to expand the synthetic CC toolkit through establishing a “minimalistic” set of orthogonal,de novoCC peptides that comprise 3.5 heptads in length and a single buried Asn to prescribe dimer formation. The designed sequences display excellent partner fidelity, confirmed via circular dichroism (CD) spectroscopy, and are corroboratedin silicousing molecular dynamics (MD) simulation. Detailed analysis of the MD conformational data highlights the importance of interhelical E@g-N@ainteractions in coordinating an extensive 6-residue hydrogen bonding network that “locks” the interchain Asn-Asn’ contact in place. The enhanced stability imparted to the Asn-Asn’ bond elicits an increase in thermal stability of CCs up to ∼15°C and accounts for significant differences in stability within the collection of similarly designed orthogonal CC pairs. The presented work underlines the utility of MD simulation as a tool for constructingde novo, orthogonal CCs, and presents an alternative handle for modulating the stability of orthogonal CCs via tuning the number of interhelical E@g-N@acontacts. Expansion of CC design rules is a key ingredient for guiding the design and assembly of more complex, intricate CC-based architectures for tackling a variety of challenges within the fields of nanomedicine and bionanotechnology.