The intracellular parasite Trypanosoma cruzi, the etiological agent of Chagas disease, sheds a developmentally regulated surface trans-sialidase, which is involved in key aspects of parasite-host cell interactions. Although it shares a common active site architecture with bacterial neuraminidases, the T.cruzi enzyme behaves as a highly efficient sialyltransferase. Here we report the crystal structure of the closely related Trypanosoma rangeli sialidase and its complex with inhibitor. The enzyme folds into two distinct domains: a catalytic beta-propeller fold tightly associated with a lectin-like domain. Comparison with the modeled structure of T.cruzi trans-sialidase and mutagenesis experiments allowed the identification of amino acid substitutions within the active site cleft that modulate sialyltransferase activity and suggest the presence of a distinct binding site for the acceptor carbohydrate. The structures of the Trypanosoma enzymes illustrate how a glycosidase scaffold can achieve efficient glycosyltransferase activity and provide a framework for structure-based drug design.
Structural basis of sialyltransferase activity in trypanosomal sialidases.,Buschiazzo A, Tavares GA, Campetella O, Spinelli S, Cremona ML, Paris G, Amaya MF, Frasch AC, Alzari PM EMBO J. 2000 Jan 4;19(1):16-24. PMID:10619840
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↑ Buschiazzo A, Tavares GA, Campetella O, Spinelli S, Cremona ML, Paris G, Amaya MF, Frasch AC, Alzari PM. Structural basis of sialyltransferase activity in trypanosomal sialidases. EMBO J. 2000 Jan 4;19(1):16-24. PMID:10619840 doi:10.1093/emboj/19.1.16