Sequence‐Dependent Heterotypic Assemblies of Intrinsically Disordered Peptides

Abstract

Intrinsically disordered regions are ubiquitous within proteins and critical for protein functions. A recent cryo‐electron microscopy study reveals that a pyrene‐conjugated hexalysine (Pyn‐KKKKKK) and a pyrene–tyrosines (EY) motif peptide (Pyn‐EYEYEY) coassemble into intrinsically disordered nanofibers through aromatic–aromatic and electrostatic interactions. To probe the sequence effects, a series of peptides is generated by mutating amino acid residues, and their assemblies are examined using negative‐stained transmission electron microscopy, fluorescence, and circular dichroism spectroscopy. Homochiral and heterochiral mixtures displayed similar morphologies, indicating a role of chirality in their structures. Sequence modifications reveal that aromatic residues patterning governs self‐assembly: “XZXZXZ” or “XXXXXZ” (X = charged residue, Z = aromatic residue) favor fiber formation, while “XXXZXZ” promotes pyrene excimer generation. Fiber assembly consistently correlates with an intermediate emission peak at 420–430 nm, suggesting a specific pyrene stacking geometry, particularly in sequences containing aromatic residues and in heterochiral mixtures of oppositely charged peptides. These findings highlight how sequence and chirality modulate aromatic–aromatic and electrostatic interactions in intrinsically disordered peptides, providing insights into heterotypic nanofiber formation and confirming the utility of lysine–tyrosine pair in rational design of supramolecular peptide materials that maintain both disorder and self‐assembly.