Cryo-EM structure and polymorphic maturation of a viral transduction enhancing amyloid fibril

Amyloid fibrils have emerged as innovative tools to enhance the transduction efficiency of retroviral vectors in gene therapy strategies. In this study, we used cryo-electron microscopy to analyze the structure of a biotechnologically engineered peptide fibril that enhances retroviral infectivity. Our findings show that the peptide undergoes a time-dependent morphological maturation into polymorphic amyloid fibril structures. The fibrils consist of mated cross-β sheets that interact by the hydrophobic residues of the amphipathic fibril-forming peptide. The now available structural data help to explain the mechanism of retroviral infectivity enhancement, provide insights into the molecular plasticity of amyloid structures and illuminate the thermodynamic basis of their morphological maturation. In this work, the authors report the Cryo-EM structure of PNF-18, a biotechnologically engineered peptide fibril that enhances retroviral infectivity. The peptide fibrils mature into polymorphic amyloid structures in a time-dependent manner. The structure provides insights into the molecular basis of peptide nanofibrils as retroviral transduction enhancers.