9FTD

Solution structure of BmSA1, the major surface antigen from Babesia microti

Summary for 9FTD

• Entry DOI: 10.2210/pdb9ftd/pdb
• NMR Information: BMRB: 51960
• Descriptor: BmGPI12, BMN1 family, BMN1-9, BmSA1 orthologue (1 entity in total)
• Functional Keywords: babesia microti, babesiosis, surface antigen, merozoite, cell adhesion
• Biological source: Babesia microti
• Total number of polymer chains: 1
• Total formula weight: 28228.71

Authors

Barthe, P.,Roumestand, C.,Mouhand, A.,Delbecq, S. (deposition date: 2024-06-24, release date: 2025-05-14, Last modification date: 2025-05-21)

Primary citation

Mouhand, A.,Pissarra, J.,Barthe, P.,Roumestand, C.,Delbecq, S.
Structural and Functional Characterization of the 28 kDa Structured Core of BmSA1, the Major Surface Antigen of Babesia Microti.
Proteins, 2025

PubMed Abstract: Babesiosis is a tick-borne disease that poses a significant threat to animal health worldwide. In addition, climate change and the risk of human-to-human transmission through blood transfusion have made babesiosis an emerging disease in humans. Babesiosis is caused by the intraerythrocytic development of protozoan parasites from the genus Babesia, which belongs to the apicomplexan phylum that notably includes the more-widely studied causative agent of malaria, Plasmodium falciparum. Of the several hundred Babesia species identified so far, only a few are known to infect humans, with B. microti being the most prevalent and responsible for most of the clinical cases reported to date. There is no licensed vaccine for B. microti, and the development of a reliable serological diagnostic test would contribute to ensuring the safety of blood transfusions. The identification and characterization of parasite surface proteins are important steps in achieving this aim. One such protein is the GPI-anchored Major Surface Antigen BmSA1 (also known as BmGPI12), which is expressed at high levels at the surface of the merozoite. We present here the high-resolution solution structure of the 28 kDa structured core of BmSA1 (∆∆BmSA1) obtained through NMR spectroscopy. The structure of BmSA1 appears unrelated to the previously published structures of the major surface antigens of B. divergens (Bd37) or of B. canis (Bc28.1), which are thought to play a similar role in parasite invasion. We also define the erythrocyte binding function of ∆∆BmSA1, using NMR spectroscopy to map the binding interface. Finally, we used bioinformatic tools to map the potential epitopes of antibodies at the surface of the structured core of BmSA1.

PubMed: 40345974
DOI: 10.1002/prot.26836

Experimental method

SOLUTION NMR