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Characterization of the GXXXG motif in the first transmembrane segment of Japanese encephalitis virus precursor membrane (prM) protein

Abstract The interaction between prM and E proteins in flavivirus-infected cells is a major driving force for the assembly of flavivirus particles. We used site-directed mutagenesis to study the potential role of the transmembrane domains of the prM proteins of Japanese encephalitis virus (JEV) in prM-E heterodimerization as well as subviral particle formation. Alanine insertion scanning mutagenesis within the GXXXG motif in the first transmembrane segment of JEV prM protein affected the prM-E heterodimerization; its specificity was confirmed by replacing the two glycines of the GXXXG motif with alanine, leucine and valine. The GXXXG motif was found to be conserved. | Lin et al. Journal of Biomedical Science 2010 17 39 http www.jbiomedsci.eom content 17 1 39 a NSC Tha cost of publication In Journal of Blomodlcal Science Is boms by tlM National Science Council Taiwan JOURNAL OF BIOMEDICAL SCIENCE RESEARCH Open Access Characterization of the GXXXG motif in the first transmembrane segment of Japanese encephalitis virus precursor membrane prM protein Ying-Ju Lint1 Jia-Guan Peng22 and Suh-Chin Wu 2 3 Abstract The interaction between prM and E proteins in flavivirus-infected cells is a major driving force for the assembly of flavivirus particles. We used site-directed mutagenesis to study the potential role of the transmembrane domains of the prM proteins of Japanese encephalitis virus JEV in prM-E heterodimerization as well as subviral particle formation. Alanine insertion scanning mutagenesis within the GXXXG motif in the first transmembrane segment of JEV prM protein affected the prM-E heterodimerization its specificity was confirmed by replacing the two glycines of the GXXXG motif with alanine leucine and valine. The GXXXG motif was found to be conserved in the JEV serocomplex viruses but not other flavivirus groups. These mutants with alanine inserted in the two prM transmembrane segments all impaired subviral particle formation in cell cultures. The prM transmembrane domains of JEV may play importation roles in prM-E heterodimerization and viral particle assembly. Background Japanese encephalitis virus JEV is a small enveloped positive-strand RNA virus that belongs to the genus Fla-vivirus of the family Flaviviridae 1 2 . The RNA genome of all flaviviruses contain sequences that code for three structural protein genes capsid C membrane precursor prM and envelope E and seven non-structural protein genes NS1 NS2A NS2B NS3 NS4A NS4B NS5 as well as flanking un-translated regions 1 2 . The flavivirus assembly process includes i interaction of prM and E proteins by heterodimer formation in the endoplasmic reticulum ER ii encapsulation