Autographa californica multiple nucleopolyhedrovirus GP64 protein: Analysis of domain I and V amino acid interactions and membrane fusion activity

Abstract

The Autographa californica multiple nucleopolyhedrovirus GP64 is a class III viral fusion protein. Although the post-fusion structure of GP64 has been solved, its pre-fusion structure and the detailed mechanism of conformational change are unknown. In GP64, domain V is predicted to interact with two domain I segments that flank fusion loop 2. To evaluate the significance of the amino acids involved in these interactions, we examined 24 amino acid positions that represent interacting and conserved residues within domains I and V. In several cases, substitution of a single amino acid involved in a predicted interaction disrupted membrane fusion activity, but no single amino acid pair appears to be absolutely required. We identified 4 critical residues in domain V (G438, W439, T452, and T456) that are important for membrane fusion, and two residues (G438 and W439) that appear to be important for formation or stability of the pre-fusion conformation of GP64.

Baculovirus Entry and Egress from Insect Cells

“…Experimental studies have identified amino acid positions in the GP64 fusion loops (102,104,110,126,137) as well as in the transmembrane and pretransmembrane domains (162)(163)(164) that are important for several of these sequential steps in GP64-membrane interactions and fusion. In addition, domains important for stabilizing the prefusion and postfusion structures of GP64 have been examined (160,165). Understanding the mechanisms of GP64 triggering and membrane fusion will ultimately require a prefusion structure of GP64, as well as intermediate structures associated with the conformational change.…”

Impact of Molecular Modification on the Efficiency of Recombinant Baculovirus Vector Invasion to Mammalian Cells and Its Immunogenicity in Mice

“…The classic display technology involves inserting the target gene between the signal peptide and the extracellular domain of the envelope protein gene, which can display the target stably and efficiently without affecting the life cycle of the baculovirus [9,10]. Proteins widely used for display include low pH-mediated membrane-promoting fusion proteins, including GP64 (group I type baculovirus), F protein (group II type baculovirus), and non-polar protein VSVG (vesicular stomatitis virus G protein) [11][12][13].…”