4X42

Crystal structure of DEN4 ED3 mutant with epitope two residues substituted from DEN3 ED3

Summary for 4X42

• Entry DOI: 10.2210/pdb4x42/pdb
• Related: 3WE1
• Descriptor: Envelope protein E, SULFATE ION (3 entities in total)
• Functional Keywords: sero-specificity, epitope graft mutants, elisa, structural protein, immune system
• Biological source: Dengue virus type 4 (DENV-4)
• Total number of polymer chains: 6
• Total formula weight: 69529.45

Authors

Kulkarni, M.R.,Islam, M.M.,Numoto, N.,Elahi, M.M.,Ito, N.,Kuroda, Y. (deposition date: 2014-12-02, release date: 2015-09-09, Last modification date: 2023-11-08)

Primary citation

Kulkarni, M.R.,Islam, M.M.,Numoto, N.,Elahi, M.,Mahib, M.R.,Ito, N.,Kuroda, Y.
Structural and biophysical analysis of sero-specific immune responses using epitope grafted Dengue ED3 mutants.
Biochim.Biophys.Acta, 1854:1438-1443, 2015

PubMed Abstract: Dengue fever is a re-emerging tropical disease and its severe form is caused by cross-reactivity between its four serotypes (DEN1, DEN2, DEN3 and DEN4). The third domain of the viral envelope protein (ED3) contains the two major putative epitopes and is a highly suitable model protein for examining the molecular determinants of a virus' sero-specificity. Here we examine d the sero-specificity and cross-reactivity of the immune response against DEN3 and DEN4 ED3 using six epitope grafted ED3 variants where the surface-exposed epitope residues from DEN3 ED3 were switched to those of DEN4 ED3 and vice versa. We prepared anti-DEN3 and anti-DEN4 ED3 serum by immunizing Swiss albino mice and measured their reactivities against all six grafted mutants. As expected, both sera exhibited strong reactivity against its own serotype's ED3, and little cross-reactivity against their counterpart serotype's ED3s. E2 played a major role in the sero-specificity of anti-DEN3 serum, whereas E1 was important for DEN4 ED3's sero-specificity. Next, the reactivity patterns corroborated our working hypothesis that sero-specificity could be transferred by grafting the surface exposed epitope residues from one serotype to the other. To analyze the above results from a structural viewpoint, we determined the crystal structure of a DEN4 ED3 variant, where E2 was grafted from DEN3 ED3, at 2.78Å resolution and modeled the structures of the five remaining grafted variants by assuming that the overall backbone remained unchanged. The examination of the electrostatic and molecular surfaces of the variants suggested some further rationale for the sero-specificity of the immune responses.

PubMed: 26160751
DOI: 10.1016/j.bbapap.2015.07.004

Experimental method

X-RAY DIFFRACTION (2.78 Å)