Viral Transduction Enhancing Effect of EF‐C Peptide Nanofibrils Is Mediated by Cellular Protrusions

Abstract

Self‐assembling peptide nanofibrils (PNF) have gained increasing attention as versatile molecules in material science and biomedicine. One important application of PNF is to enhance retroviral gene transfer, a technology that has been central for gene therapy approaches. The best‐investigated and commercially available PNF is derived from a 12‐mer peptide termed EF‐C. The mechanism of transduction enhancement depends on the polycationic surface of EF‐C PNF, which bind to the negatively charged membranes of viruses and cells, thereby overcoming electrostatic repulsions and increasing virion attachment and fusion. To better understand how EF‐C PNF interact with the cell surface, scanning electron and time‐lapse confocal microscopy were performed. The fibrils are found to be actively engaged by cellular protrusions such as filopodia. Consequently, chemical suppression of protrusion formation abrogates fibril binding and virion delivery to the cell surface of immortalized and primary T cells. Vice versa, induction of plasma membrane blebs result in increased fibril binding. Thus, the mechanism of PNF‐mediated viral transduction enhancement involves an active engagement of virus‐loaded fibrils by cellular protrusions, which may explain its superior performance over soluble transduction enhancers.

Data-mining unveils structure–property–activity correlation of viral infectivity enhancing self-assembling peptides

“…We observed that the interactions of peptides with cells and viruses are mostly driven by three codependent properties: (I) ordered structure (II) microscopic aggregation and (III) positive surface charge. While the importance of zeta-potential and fibril formation was already suggested for EF-C PNF in previous reports 12 , 26 , 55 , microscopic aggregation—which we found to correlate strongly with infectivity—was not systematically studied nor identified as a necessary feature before.…”

Data-Mining Unveils Structure-Property-Activity Correlation of Viral Infectivity Enhancing Self-Assembling Peptides

“…We observed that the interactions of peptides with cells and viruses are mostly driven by three codependent properties: (I) ordered structure (II) microscopic aggregation and (III) positive surface charge. While the importance of zeta-potential and fibril formation was already suggested for EF-C PNF in previous reports, [12,26,71] microscopic aggregation -which we found to correlate strongly with infectivity -was not systematically studied nor identified as a necessary feature before.…”

“…We hypothesize that µm-sized aggregates can accelerate infectivity by physical entanglement with cellular protrusions, which are actively transporting the fibril/virus complexes to the cell surface, where virions can enter the cells. [71] Interestingly, for aggregates larger than 10 µm 2 it is not the size, but rather the number of aggregates correlating with infectivity enhancement. Fibrils aggregating to few very large aggregates might simply not offer enough particles for virus-cell interactions or may be too big to get efficiently engaged by protrusions.…”

Inverse design of viral infectivity-enhancing peptide fibrils from continuous protein-vector embeddings

“…43 More recently it has also been shown that cellular protrusions actively engage EF-C fibril/virion complexes, suggesting that not only electrostatic interactions may account for bioactivity. 44 Our method demonstrates that moderately negatively charged peptide fibrils can be active if the hydrophobicity and aggregation features are both strongly pronounced. Hydrophobic amino acids such as tryptophan, phenylalanine, and cysteine can facilitate these desired properties; the continuous vector representation of peptides successfully extracts this underlying information by processing sequence and activity information of the training set.…”