Near-atomic structure of Japanese encephalitis virus reveals critical determinants of virulence and stability

Abstract

Although several different flaviviruses may cause encephalitis, Japanese encephalitis virus is the most significant, being responsible for thousands of deaths each year in Asia. The structural and molecular basis of this encephalitis is not fully understood. Here, we report the cryo-electron microscopy structure of mature Japanese encephalitis virus at near-atomic resolution, which reveals an unusual “hole” on the surface, surrounded by five encephalitic-specific motifs implicated in receptor binding. Glu138 of E, which is highly conserved in encephalitic flaviviruses, maps onto one of these motifs and is essential for binding to neuroblastoma cells, with the E138K mutation abrogating the neurovirulence and neuroinvasiveness of Japanese encephalitis virus in mice. We also identify structural elements modulating viral stability, notably Gln264 of E, which, when replaced by His264 strengthens a hydrogen-bonding network, leading to a more stable virus. These studies unveil determinants of neurovirulence and stability in Japanese encephalitis virus, opening up new avenues for therapeutic interventions against neurotropic flaviviruses.

Electrostatic interactions at the five-fold axis alter heparin-binding phenotype and drive EV-A71 virulence in mice

“…Kobayashi and colleagues reported that EGK virus is less virulent compared to EEK due to the former harbouring the VP1-G145 residue, enabling the virus to adsorb more strongly to HS, resulting in attenuated virulence in SCARB2-expressing transgenic mice [56]. Our findings that a strong heparin-binding phenotype attenuates virulence is also observed in other viruses, including Sindbis virus [33], Venezuelan equine encephalitis virus [55], West Nile virus [30], yellow fever virus [31] and Japanese encephalitis virus [57]. Using a monkey model, Zhang et al showed that the establishment of viremia was strongly correlated with EV-A71 neuroinvasion into CNS [16].…”

Posttranslational modifications of CENP-A: marks of distinction

“…Amino-terminal trimethylation of CENP-A, which was identified through high-resolution mass spectrometry, has emerged as a regulator of CENP-A function and is required for precise chromosome segregation during mitosis (Bailey et al 2013; Sathyan et al 2017). Similar to histone H3, the initiating methionine is constitutively removed from CENP-A and the enzyme NRMT1 trimethylates the alpha amino group of the exposed glycine residue on CENP-A (Fig.…”

“…Chromosome missegregation errors also occur when CENP-A cannot be methylated, but these errors are independent of p53 status. CENP-A methylation mutants leads to uncontrolled cell proliferation, and when expressed in p53 − / − null cells, results in early onset of tumors in nude mice, suggesting that misregulation of CENP-A methylation may have implications in cancer (Sathyan et al 2017). …”

“…Gly-1 trimethylation, on the other hand, regulates the localization of other components of CCAN, namely CENP-T and CENP-I without affecting CENP-C (Fig. 2b) (Sathyan et al 2017). …”

“…Growing evidence suggests the potential alteration of CENP-A PTMs associated with cancer progression. The observation that a CENP-A methylation defective mutant together with loss of p53 , promotes tumor development in nude mice and the correlation of Ser-18 hyperphophorylation with cyclin E-driven tumors, indicate a potential role of CENP-A modifications in cancer (Sathyan et al 2017; Takada et al 2017). Large-scale proteomic studies have revealed several additional modifications; the biological relevance of which is yet to be discovered (please see http://www.phosphositeplus.com).…”