1.A.61 The Insect Nodavirus Channel-forming Chain F (Gamma-Peptide) Family
Membrane translocation of the single-stranded RNA genomes of nodaviruses has been proposed to be mediated by direct lipid-protein interactions between a post-assembly autocatalytic cleavage product from the capsomere and the target membrane. A 21-residue Met-->Nle (norleucine) variant of the amino-terminal helical domain (denoted here as gamma1) of the cleavage peptide in Flock House nodavirus (FHV) was synthesized (Bong et al., 1999). The synthetic peptide gamma1 increases membrane permeability to hydrophilic solutes, as judged by fluorescence experiments with liposome-encapsulated dyes and ion-conductance measurements. The helical domain of the FHV cleavage product partitions spontaneously into lipid bilayers and increases membrane permeability, consistent with the postulated mechanism for viral genome translocation (Janshoff et al., 1999). The existence of a membrane-binding domain in the FHV cleavage sequence suggests peptide-triggered disruption of the endosomal membrane as a prelude to viral uncoating in the host cytoplasm (Bong et al., 1999).
The reactions catalyzed by gamma-peptide are:
small molecules/ions/nucleocapsid (out) small molecules/ions/nucleocapsid (in)