Analysis of DENV-2 NS5 Methyltransferase Reveals Structural Features and Potential Epitope Regions

Background

The NS5 Nterminal Methyltransferase (MTase) of Dengue Virus Serotype2 (DENV2) catalyzes RNA cap methylation. MTase is indispensable for replication and is an attractive target for antivirals and epitopebased vaccines.

Purpose

To characterize the DENV-2 NS5 N-terminal Methyltransferase (MTase) domain using integrated computational structural and immunoinformatic analyses. To identify surface-exposed linear B-cell epitope candidates and potential phosphorylation sites that could support antiviral, diagnostic, or vaccine development.

Materials and Methods

We profiled the MTase domain (residues 1-263) using an integrated computational workflow that included physicochemical characterization, secondarystructure and disorder prediction, residue contact mapping, and 3D modeling. Immunoinformatic screens mapped linear Bcell accessible regions and predicted serine/threonine/tyrosine phosphorylation sites.

Results

The protein comprises 263 amino acids (~29.37 kDa) with a basic theoretical pI (~9.33). Predicted secondary structure and contact topology support a Rossmann-like MTase fold, characterized by alternating β-strands and α-helices. There is low intrinsic disorder outside the termini, which is consistent with a wellpacked catalytic domain. Antigenicity profiling highlights surfaceexposed stretches near the Nterminus, a central loop region, and the Cterminus. Seven short linear peptides (6-13 residues) were consistently prioritized between positions 10-254. The highestscoring epitope is located in the Cterminal region (~242-254). Multiple putative phosphorylation sites were detected, forming serine/threoninerich clusters around ~20-40, ~120-140, and ~200-240. These may regulate enzyme function or host interactions.

Conclusion

This study delineates the structural organization and immunogenic landscape of the DENV2 NS5 MTase domain. It proposes discrete peptide candidates for experimental validation in the context of diagnostics or vaccine design. The modeled fold and residuelevel features provide a framework for structureguided inhibitor discovery.