title: Design and analysis of post-fusion 6-helix bundle of heptad repeat regions from Newcastle disease virus F protein.
abstract: Fusion of paramyxovirus to the cell involves receptor binding of the HN glycoprotein and a number of conformational changes of F glycoprotein. The F protein is expressed as a homotrimer on the virus surface. In the present model, there are at least three conformations of F protein, i.e. native form, pre-hairpin intermediate and the post-fusion state. In the post-fusion state, the two highly conserved heptad repeat (HR) regions of F protein form a stable 6-helix coiled-coil bundle. However, no crystal structure is known for this state for the Newcastle disease virus, although the crystal structure of the F protein native form has been solved recently. Here we deployed an Escherichia coli in vitro expression system to engineer this 6-helix bundle by fusion of either the two HR regions (HR1, linker and HR2) or linking the 6-helix [3 x (HR1, linker and HR2)] together as a single chain. Subsequently, both of them form a stable 6-helix bundle in vitro judging by gel filtration and chemical cross-linking and the proteins show salient features of an alpha-helix structure. Crystals diffracting X-rays have been obtained from both protein preparations and the structure determination is under way. This method could be used for crystallization of the post-fusion state HR structures of other viruses.
authors.affiliation: Department of Molecular Virology, Institute of Microbiology, Chinese Academy of Sciences, Zhongguancun Beiyitiao, Beijing 100080, China.
authors.forename: Jieqing
authors.initials: J
authors.lastname: Zhu
authors.forename: Pengyun
authors.initials: P
authors.lastname: Li
authors.forename: Tinghe
authors.initials: T
authors.lastname: Wu
authors.forename: Feng
authors.initials: F
authors.lastname: Gao
authors.forename: Yi
authors.initials: Y
authors.lastname: Ding
authors.forename: Catherine W-H
authors.initials: CW
authors.lastname: Zhang
authors.forename: Zihe
authors.initials: Z
authors.lastname: Rao
authors.forename: George F
authors.initials: GF
authors.lastname: Gao
authors.forename: Po
authors.initials: P
authors.lastname: Tien
mesh_terms: D000595:Amino Acid Sequence; D002850:Chromatography, Gel; D002942:Circular Dichroism; D003460:Crystallization; D008969:Molecular Sequence Data; D009522:Newcastle disease virus / Q000378:metabolism*; D017433:Protein Structure, Secondary; D014760:Viral Fusion Proteins / Q000378:metabolism*
chemical_list: D014760:Viral Fusion Proteins