Dawei Wang ¹ Yuyi Shi ^1* Ziwen Cheng ^1* Like Luo ^1* Kuo Cheng ^1* Shengqi Gan ^1* Che Liu ^1* Zeliang Chen ^2* Baoling Yang ^1*

• ¹ Jinzhou Medical University, Jinzhou, China
• ² Shenyang Agricultural University, Shenyang, Liaoning, China

Background: Toxoplasma gondii (T. gondii) is a widespread, zoonotic protozoan intracellular parasite with a complex life cycle, which can cause toxoplasmosis, a potentially serious disease. During the invasion process, T. gondii proteins first bind to the relevant host cell receptors, such as glycosaminoglycan molecule (GAG-binding motif), which is one of the main receptors for parasites or virus to infect host cells.However, research on TGME49_216510 (T. gondii Trx21), a protein from Toxoplasma gondii, is limited. Methods: Bioinformatics analysis of the Trx21 protein was performed firstly. And specific primers were then designed using the conserved domain and GAG-binding motif to amplify, express, and purify a fragment of the Trx21 protein.The purified Trx21-GST protein was used for antioxidant and cell adhesion experiments.Simultaneously, mice were immunized with Trx21-His to generate specific polyclonal antibodies for subcellular localization analysis. Results: The Trx21 protein, consisting of 774 amino acids, included a transmembrane region, three GAG-binding motifs, and a Thioredoxin-like domain. The recombinant Trx21-His protein had a molecular mass of about 31 kDa, while the Trx21-GST protein had a molecular mass of about 55 kDa, which was analyzed by SDS-PAGE and Western blot. Subcellular localization analysis by IFA revealed that Trx21 is predominantly distributed in the cytoplasm of T. gondii.Furthermore, Trx21 exhibited a protective effect on supercoiled DNA against metalcatalyzed oxidation (MCO) and demonstrated adhesion abilities to Vero cells.These results indicate that Trx21 plays an important role in host cell interaction and oxidative damage.