Structural study of the C-terminal domain of non-structural protein 1 and capsid protein from Japanese encephalitis virus

Poonsiri, T
(2018) Structural study of the C-terminal domain of non-structural protein 1 and capsid protein from Japanese encephalitis virus. PhD thesis, University of Liverpool.

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Japanese encephalitis virus (JEV) is a mosquito-transmitted Flavivirus that is closely related to other emerging viral pathogens including dengue (DENV), West Nile (WNV) and Zika viruses (ZIKV). JEV infection can result in meningitis and encephalitis, which in severe cases cause permanent brain damage and death. JEV occurs predominantly in rural areas throughout South East Asia, the Pacific islands, and the Far East, causing around 68,000 cases worldwide each year. There is no specific treatment for JEV. This study aims to determine the molecular structure of new potential drug targets for JEV. In this study, the JEV non-structural protein 1 C-terminal β-ladder domain (C-NS1) is presented at 2.1 Å resolution. The crystal structure of C-JEVNS1 shares a conserved fold with flavivirus C-NS1 domains. The surface charge distribution of C-JEVNS1 is similar to WNV and ZIKV but is significantly different from DENV. Analysis of the C-JEVNS1 structure, in silico molecular dynamics simulations and experimental solution small angle X-ray scattering, indicate extensive loop flexibility on the exterior of the protein. It is proposed that this together with charge distribution on the exterior of the protein influence NS1-host protein interaction specificity which may impact on pathogenicity. These factors may also affect the interaction with the monoclonal antibody, 22NS1, which is protective against WNV infection. Liposome and heparin binding assays indicate that only the N-terminal region of NS1 participates in the interaction with lipidic membranes and that sulphate binding sites are not the glycosaminoglycans binding interfaces. For the first time, the crystal structure of the JEV capsid protein at 1.98 Å is also reported and compared to the existing flavivirus capsid protein. JEV capsid shows helical secondary structure (α helixes 1-4) and protein folding similar to DENV and WNV capsid proteins. It forms a homodimer by antiparallel pairing with another subunit (‘), α helix 1-1’, 2-2’, and 4-4’. The capsid dimer is believed to be the building block of the nucleocapsid. The flexibility of the N-terminal α helix 1 of the capsid could be important for its function. This dimer model agrees with a previous suggestion that the capsid protein interacts with RNA via the basic rich C-terminal, α4-α4’, and associates with lipid bilayers at the opposite hydrophobic, α2-α2’.

Item Type: Thesis (PhD)
Divisions: Faculty of Health and Life Sciences > Faculty of Health and Life Sciences
Depositing User: Symplectic Admin
Date Deposited: 16 Aug 2018 13:22
Last Modified: 16 Jan 2024 17:21
DOI: 10.17638/03021941