The high
typhoid incidence rate in developing and under-developed countries emphasizes the need for a rapid, affordable and accessible diagnostic test for effective
therapy and disease management. TYPHIDOT®, a rapid dot
enzyme immunoassay test for
typhoid, was developed from the discovery of a ∼50 kDa
protein specific for Salmonella enterica serovar Typhi. However, the structure of this
antigen remains unknown till today. Studies on the structure of this
antigen are important to elucidate its function, which will in turn increase the efficiency of the development and improvement of the
typhoid detection test. This paper described the predictive structure and function of the antigenically specific
protein. The homology modeling approach was employed to construct the three-dimensional structure of the
antigen. The built structure possesses the features of TolC-like outer
membrane protein. Molecular docking simulation was also performed to further probe the functionality of the
antigen. Docking results showed that hexamminecobalt, Co(NH(3))(6)(3+), as an inhibitor of TolC
protein, formed favorable hydrogen bonds with D368 and D371 of the
antigen. The single point (D368A, D371A) and double point (D368A and D371A) mutations of the
antigen showed a decrease (single point mutation) and loss (double point mutations) of binding affinity towards hexamminecobalt. The architecture features of the built model and the docking simulation reinforced and supported that this
antigen is indeed the variant of outer
membrane protein, TolC. As channel
proteins are important for the virulence and survival of bacteria, therefore this ∼50 kDa channel
protein is a good specific target for
typhoid detection test.