Abstract:

Objective: To predict and analyze the structure and function of Mycobacterium tuberculosis (MTB) epitope-tandem protein W541 by bioinformatics method. Methods: W541 protein constructed in our laboratory was encoded by a novel multi-antigen epitope-tandem DNA vaccine composed of the epitopes of MTB proliferative antigens Ag85A, Ag85B, latent-related antigens Rv3407 and Rv1733c. Its amino acid sequence of physicochemical properties, hydrophilic (hydrophobic), transmembrane helix, secondary and tertiary structures, subcellular localization, signal peptide, glycosylation and phosphorylation sites, B cell, helper T (Th) and cytotoxic T lymphocyte (CTL) epitopes, the protein interaction network, the homology between W541 protein and human protein was analyzed using bioinformatics softwares ProtParam, Protscale, TMHMM, SOPMA, SWISS-MODEL, PSORT, SignalP, NetNGlyc, NetPhos, SYFPEITHI, RANKPEP, IEDB, NetMHC, STRING, and EXPASY, respectively. Results: W541 protein was composed of 704 amino acids, with the molecular formula of C₃₃₂₉H₅₀₃₅N₉₂₃O₉₉₃S₂₄, the instability index of 45.37, which was hydrophilic unstable protein. The proportions of α-helix, β-fold, β-corner and irregular crimp in its secondary structure were 26.99%, 19.03%, 11.51% and 42.47%, respectively. It had no transmembrane helix region or signal peptides, which was an intracellular membrane protein. W541 protein had 6 glycosylation sites, and 62 phosphorylation sites, including 15 threonine, 35 serine and 12 tyrosine phosphorylation sites, respectively. W541 protein had multiple potential T cell and B cell epitopes. W541 protein interacted with 10 proteins. The amino acid sequence of W541 protein had less than 3.27% homology with the human protein. Conclusion: MTB epitope-tandem protein W541 has multiple potential T-cell and B-cell epitopes. Among them, T-cell epitopes were dominant, which may have better immunogenicity, play an important regulatory role and lay a foundation for further animal experimental evaluation.

Key words: Immunity, Mycobacterium tuberculosis, Antigens, Models,structural