Abstract
AbstractAmyloid‐like peptide nanofibrils (PNFs) are abundant in nature providing rich bioactivities and playing both functional and pathological roles. The structural features responsible for their unique bioactivities are, however, still elusive. Supramolecular nanostructures are notoriously challenging to optimize, as sequence changes affect self‐assembly, fibril morphologies, and biorecognition. Herein, the first sequence optimization of PNFs, derived from the peptide enhancing factor‐C (EF‐C, QCKIKQIINMWQ), for enhanced retroviral gene transduction via a multiparameter and a multiscale approach is reported. Retroviral gene transfer is the method of choice for the stable delivery of genetic information into cells offering great perspectives for the treatment of genetic disorders. Single fibril imaging, zeta potential, vibrational spectroscopy, and quantitative retroviral transduction assays provide the structure parameters responsible for PNF assembly, fibrils morphology, secondary and quaternary structure, and PNF‐virus‐cell interactions. Optimized peptide sequences such as the 7‐mer, CKFKFQF, have been obtained quantitatively forming supramolecular nanofibrils with high intermolecular β‐sheet content that efficiently bind virions and attach to cellular membranes revealing efficient retroviral gene transfer.
Highlights
Peptide nanofibrils (PNFs) are ubiquitous in nature
EF-C instantaneously forms positively charged PNFs (ζ = +17.7 mV) with high conversion rates (CR: 95%) and it is used as an internal standard to compare the infectivity enhancement of the peptide nanofibrils in different sets of experiments, that is, on different days
We have reported the first sequence optimization of peptides forming bioactive amyloid-like PNFs that enhance retroviral gene transduction based on single fibril analysis and quantitative infection data
Summary
Peptide nanofibrils (PNFs) are ubiquitous in nature. They are formed by spontaneous self-assembly and exert many vital functions in living organisms. The C-terminal NMWQ domain represents a fragment of the β20/21 strand in the gp120 HIV-1 envelope protein region that has been proposed to constitute the primary HIV binding site for the CD4 receptors of immune cells[41] and to play a crucial role for the transduction enhancement of PNFs. The hexameric KIKQII fragment features an amphiphilic pattern with three hydrophobic isoleucine (I) and two positively charged lysine (K) residues. Virions were exposed to increasing concentrations of PNFs and the mixtures were used to infect TZM-bl reporter cells,[44] which are widely used to study HIV infection rates These cells are genetically engineered to express the HIV receptors CD4 and CXCR4/CCR5 and contain a stably integrated β-galactosidase gene under the control of the viral long terminal repeat promotor region. None of the peptides tested in this study affected cell viability within the concentrations used for transduction studies (Figure S2, Supporting Information)
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