Following cleavage of solubilizing tag (Thioredoxin, T) from T-P-AB2-L fusion protein, self-assembly peptide P114(P) possibly prevents or interferes with the spontaneous LL-37 directed self-assembly in P-AB2-L into nanospears (upper panel, 1). The flexible GS linker possibly caused dynamic and flexible P114 conformational changes. However, in the presence of divalent cations/salts, the metal ions (e.g., Mg2+ions) bind to/coordinate with specific amino acids at the peptide–peptide interface to allow or subsequently induce nanospear formation. The addition of excess divalent cations form longer and polydisperse protein nanospears (lower panel, 2). Color representation in the cartoons: thioredoxin, T (orange); self-assembly peptide P114, P (green); flexible GS linker (black); endolysin LysAB2, AB2 (pink); helical/rigid linker (blue); antimicrobial peptide LL-37, L (light green).
