Zika Virus Capsid Anchor Forms Cytotoxic Amyloid-like Fibrils

Capsid-anchor (CA) of Zika virus (ZIKV) is a small, single-pass transmembrane sequence that separates the capsid (C) protein from downstream pre-membrane (PrM) protein. During ZIKV polyprotein processing, CA is cleaved-off from C and PrM and left as a membrane-embedded peptide. CA plays an essential role in the assembly and maturation of the virus. However, its independent folding behavior is still unknown. Since misfolding and aggregation propensity of transmembrane proteins are now increasingly recognized and has been linked to several proteopathic disorders. Therefore, in this study, we investigated the amyloid-forming propensity of CA at physiological conditions. We observed aggregation behavior of CA peptide using dyebinding assays and ThT kinetics. The morphological analysis of CA aggregates explored by high-resolution microscopy (TEM and AFM) revealed characteristic amyloid-like fibrils. Further, the effect on mammalian cells exhibited the cytotoxic nature of the CA amyloid-fibrils. Our findings collectively shed light on the amyloidogenic phenomenon of flaviviral protein, which may contribute to their infection. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=80 SRC="FIGDIR/small/381988v1_ufig1.gif" ALT="Figure 1"> View larger version (20K): org.highwire.dtl.DTLVardef@2d07b7org.highwire.dtl.DTLVardef@55bf11org.highwire.dtl.DTLVardef@1732eb5org.highwire.dtl.DTLVardef@ff73f9_HPS_FORMAT_FIGEXP M_FIG Schematic representation of Zika virus Capsid anchor forming amyloid aggregates with cytotoxic and hemolytic properties. C_FIG