Analysis and structure prediction of Toxoplasma gondii microneme protein 3

Toxoplasma gondii is a very successful zoonotic parasite and a causative agent for toxoplasmosis disease. T. gondii is an obligate intracellular protozoan parasite that comes from Apicomplexan phylum. The infection is asymptomatic in healthy individual but may cause death to the individual with low immunity such as in HIV patients. Microneme protein 3 [MIC3] is the secreted adhesive agents that are expressed in all stages of T. gondii life cycle [tachyzoites, bradyzoites and sporozoites]. The bioinformatics analysis such as sequence analysis and the structure analysis were performed to MIC3 gene of T. gondii to study its potential in DNA vaccine development. The sequence analysis was performed using Basic Local Alignment Search Tool [BLAST] while structure of the protein was predicted by using the Predict Secondary Structure [RaptorX] web server. The analysis revealed that the MIC3 gene coded the sequence for EGF3 and P Lasmod_Pvs28 domain. The domain is a conserved region within the protein sequence that is significant and can exist independently. The predicted model was constructed based Human Notch-1 EGFS 11–13 and crystal structure of the Myxococcus Xanthus hemagglutinin as template since its scored the highest similarity with MIC3 protein. Human Notch-1 EGFS 11–13 consist of calcium, chloride sodium ion compound and known as a receptor for membrane-bound ligands while Myxococcus Xanthus hemagglutinin is in charge in carbohydrate binding as it possesses lectin ligand. Thus, from the structure it can be deducted that the signalling activity will occurs at the Human Notch-1 EGFS 11–13 part and the binding activity will take place at the Myxococcus Xanthus hemagglutinin site. The finding may lead to advance understanding of the MIC3 protein structure and its potential as DNA vaccine against T. gondii.