Nature of Amorphous Hydrophilic Block Affects Self-Assembly of an Artificial Viral Coat Polypeptide

Abstract

Consensus motifs for sequences of both crystallizable and amorphous blocks in silks and natural structural analogues of silks vary widely. To design novel silklike polypeptides, an important question is therefore how the nature of either the crystallizable or the amorphous block affects the self-assembly and resulting physical properties of silklike polypeptides. We address herein the influence of the amorphous block on the self-assembly of a silklike polypeptide that was previously designed to encapsulate single DNA molecules into rod-shaped viruslike particles. The polypeptide has a triblock architecture, with a long N-terminal amorphous block, a crystallizable midblock, and a C-terminal DNA-binding block. We compare the self-assembly behavior of a triblock with a very hydrophilic collagen-like amorphous block (GXaaYaa)132 to that of a triblock with a less hydrophilic elastin-like amorphous block (GSGVP)80. The amorphous blocks have similar lengths and both adopt a random coil structure in solution. Nevertheless, atomic force microscopy revealed significant differences in the self-assembly behavior of the triblocks. If collagen-like amorphous blocks are used, there is a clear distinction between very short polypeptide-only fibrils and much longer fibrils with encapsulated DNA. If elastin-like amorphous blocks are used, DNA is still encapsulated, but the polypeptide-only fibrils are now much longer and their size distribution partially overlaps with that of the encapsulated DNA fibrils. We attribute the difference to the more hydrophilic nature of the collagen-like amorphous block, which more strongly opposes the growth of polypeptide-only fibrils than the elastin-like amorphous blocks. Our work illustrates that differences in the chemical nature of amorphous blocks can strongly influence the self-assembly and hence the functionality of engineered silklike polypeptides.

Self-Assembly of Elastin-like Polypeptide Brushes on Silica Surfaces and Nanoparticles

“…A final mild bake-out procedure was sufficient to further purify the desired proteins to an acceptable level (Figure 6a). As previously observed, 57,58 the poor SDS-binding of ELPs leads to anomalously high molecular weights in SDS-PAGE when compared with globular protein molecular weight standards. To confirm the identity of the polypeptides, MALDI-TOF spectra were determined for the purified proteins (Figure 6b).…”

Non‐Pore Dependent and MMP‐9 Responsive Gelatin/Silk Fibroin Composite Microparticles as Universal Delivery Platform for Inhaled Treatment of Lung Cancer

“…[ 32 ] Previous studies have demonstrated that polymer chains with certain rigidity and orientation can accelerate the folding of SF secondary structure. [ 33 ] Therefore, we wondered what effect the introduction of MMP‐9 sensitive gelatin could have on the self‐assembly of SF, considering the typical rigid tri‐helix structure of gelatin. Excitingly, we observed an obvious microphase separation in the Gel/SF mixed solution under gentle ultrasound, as observed via liquid‐phase scanning microscopy (LSM) and atomic force microscope (AFM) ( Figure ai,ii).…”

Self‐assembling systems comprising intrinsically disordered protein polymers like elastin‐like recombinamers

“…In the study published by Luo and Kiick, 100 The study published by Willems et al 102 investigates the influence of the amorphous or crystallizable block on SA of a silk-like triblock polypeptide that was previously designed to encapsulate single DNA molecules to give rise to rod-shaped virus-like particles (VLPs). This polypeptide has a triblock architecture consisting of a long Nterminal amorphous block, a crystallizable middle block, and a Cterminal DNA-binding block.…”