Structure Function Studies on a Lipid Binding Protein H7 from Vaccinia Virus
Abstract
H7 as a member of the recently identified viral membrane assembly proteins (VMAPs) plays a key role in poxvirus membrane biogenesis. Although the detailed manner of the poxvirus membrane biogenesis remains largely unclear, it is suggested that H7 works together with other VMAPs to facilitate the acquisition of membrane from the host’s endoplasmic reticulum (ER). In eukaryotes, phosphoinositides and their binding proteins have been known for their importance in membrane and protein trafficking. From our previous study, a phosphoinositide-binding site was identified on two regions of the H7 protein, including the C-terminal tail and a surface patch that is comprised of basic residues. Through lipid overlay and fluorescence polarization-based lipid binding assays, the binding of H7 with phosphoinositides, PI3P and PI4P, was confirmed. A model, in which a positively charged pocket for binding phosphoinositdes was formed by two regions interacting with each other and the C-terminal’s possible function serving as a switch, was proposed from the previous structure-function studies. Yet due to the intrinsic nature, the 29 residues at the C-terminal tail were not visible in the published H7 structure. In this study, we aim to solve the complete structure of H7 in complex with phosphoinositides PI3P, PI4P. Due to the lack of sequence homology of H7 to proteins outside the poxvirus family, the structure-function study of H7 with lipid can provide a novel perspective into the detailed mechanism of poxvirus membrane biogenesis.
Collections
- OSU Theses [15752]