Análise bioinformática comparativa das proteínas de grânulos densos de toxoplasma gondii e neospora caninum

Abstract

Neospora caninum and Toxoplasma gondii are closely related parasites within the Apicomplexa phylum, with a significant impact on human and veterinary medicine. N. caninum is one of the main causes of reproductive failure in cattle, while T. gondii infects a significant part of the human population. Both parasites share complex life cycles, and their ability to secrete dense granule proteins (GRAs) plays a key role in their pathogenesis. GRAs are important for the intracellular survival of these parasites, as they influence host-parasite interactions, the acquisition of nutrients and the modulation of the host's immune responses. Despite the great similarity between these parasites, little research has focused on N. caninum GRAs (NcGRAs), and their comparative analysis with T. gondii GRAs (TgGRAs) remains poorly studied. The aim of this study is to fill this gap by carrying out a bioinformatic analysis using public databases, providing information on the conservation and divergence of GRAs in these parasites. This study compiles and characterises a list of GRAs in T. gondii and N. caninum, using open-access databases. Bioinformatic analyses, including orthology, synteny, and evaluation of structural features such as domain analysis and conserved motifs, are performed. The 3D structures of the GRAs are predicted using AlphaFold2, allowing a detailed comparison of their tertiary structures. The main findings of the study include the identification of 185 TgGRAs and 146 orthologous NcGRAs. These proteins exhibit different identities, with the majority falling within the 61-70% range, suggesting variations in functional roles. In addition, differences in transmembrane domains and signal peptides indicate possible disparities in subcellular localisation and functionality between GRAs. The presence of other conserved domains highlights shared functional elements between these GRAs. 3D structural analysis reveals differences and similarities in the molecular architecture of these GRAs, shedding further light on their complexities. This research contributes to a deeper understanding of the molecular aspects, functional diversity and evolutionary history of TgGRAs and NcGRAs, which may have far-reaching implications for the development of interventions and therapies for toxoplasmosis and neosporosis infections.