Structural characterization of TbFam50, TbPSSA2, and TCCISSA, surface proteins expressed by the trypanosome inside the tsetse vector
Date
2016-05-30
Authors
Ramaswamy, Raghavendran
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Abstract
Vector-borne diseases such as malaria, leishmaniasis, and African trypanosomiasis are a major scourge to humans and animals in some of the most impoverished nations across the globe. Enabling the transmission of these disease-causing pathogens is a highly sophisticated molecular arsenal of surface proteins. My research focuses on biophysical characterization of these proteins with the ultimate goal of deciphering the molecular crosstalk between pathogen and vector. In support of this goal, I have selected the tsetse fly-transmitted parasites of the genus Trypanosoma, the etiological agent of African sleeping sickness, as a model system. Towards elucidating the molecular mechanism of transmission, I have attempted to characterize structurally three novel proteins; TbFam50.360, TbPSSA2, and TcCISSA and get insight into their functions. Before this study, GARP (Glutamic Acid Rich Protein from T. congolense), and VSG (Variant Surface Glycoprotein from T. brucei) were the only proteins to be structurally characterized in the vector stages of the parasite.
Our structural analysis revealed that while the N- terminal region of TbFam50.360 adopted a three-helical structure similar to previously characterized trypanosome surface proteins, ectodomains of both TbPSSA2 and TcCISSA adopted a previously uncharacterized bilobed architecture. The structural analysis further identified putative ligand binding regions in TbFam50.360 and TcCISSA. However, in the absence of binding partners, the exact function of these proteins could not be established. Our lab in conjunction with our collaborators is investigating the binding partners of these proteins within the tsetse.
The structures of TbFam50.360, TbPSSA2, and TcCISSA can be added to the repertoire of structurally characterized surface proteins expressed by trypanosomes. The information gained from these first structures of trypanosome surface proteins offer insight into their role in the trypanosome life cycle, and may, in the future, contribute to the control of African trypanosomiasis.
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Trypanosomes, tsetse, surface proteins, X-ray crystallography