7qe3
Se-M variant of B-trefoil lectin from Salpingoeca rosetta in complex with GalNAc
Structural highlights
FunctionPublication Abstract from PubMedChoanoflagellates are primitive protozoa used as models for animal evolution. They express a large variety of multi-domain proteins contributing to adhesion and cell communication, thereby providing a rich repertoire of molecules for biotechnology. Adhesion often involves proteins adopting a beta-trefoil fold with carbohydrate-binding properties therefore classified as lectins. Sequence database screening with a dedicated method resulted in TrefLec, a database of 44714 beta-trefoil candidate lectins across 4497 species. TrefLec was searched for original domain combinations, which led to single out SaroL-1 in the choanoflagellate Salpingoeca rosetta, that contains both beta-trefoil and aerolysin-like pore-forming domains. Recombinant SaroL-1 is shown to bind galactose and derivatives, with a stronger affinity for cancer-related alpha-galactosylated epitopes such as the glycosphingolipid Gb3, when embedded in giant unilamellar vesicles or cell membranes. Crystal structures of complexes with Gb3 trisaccharide and GalNAc provided the basis for building a model of the oligomeric pore. Finally, recognition of the alphaGal epitope on glycolipids required for hemolysis of rabbit erythrocytes suggests that toxicity on cancer cells is achieved through carbohydrate-dependent pore-formation. The choanoflagellate pore-forming lectin SaroL-1 punches holes in cancer cells by targeting the tumor-related glycosphingolipid Gb3.,Notova S, Bonnardel F, Rosato F, Siukstaite L, Schwaiger J, Lim JH, Bovin N, Varrot A, Ogawa Y, Romer W, Lisacek F, Imberty A Commun Biol. 2022 Sep 12;5(1):954. doi: 10.1038/s42003-022-03869-w. PMID:36097056[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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