1jc9
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TACHYLECTIN 5A FROM TACHYPLEUS TRIDENTATUS (JAPANESE HORSESHOE CRAB)
OverviewOverview
Because invertebrates lack an adaptive immune system, they had to evolve, effective intrinsic defense strategies against a variety of microbial, pathogens. This ancient form of host defense, the innate immunity, is, present in all multicellular organisms including humans. The innate immune, system of the Japanese horseshoe crab Tachypleus tridentatus, serving as a, model organism, includes a hemolymph coagulation system, which, participates both in defense against microbes and in hemostasis. Early, work on the evolution of vertebrate fibrinogen suggested a common origin, of the arthropod hemolymph coagulation and the vertebrate blood, coagulation systems. However, this conjecture could not be verified by, comparing the structures of coagulogen, the clotting protein of the, horseshoe crab, and of mammalian fibrinogen. Here we report the crystal, structure of tachylectin 5A (TL5A), a nonself-recognizing lectin from the, hemolymph plasma of T. tridentatus. TL5A shares not only a common fold but, also related functional sites with the gamma fragment of mammalian, fibrinogen. Our observations provide the first structural evidence of a, common ancestor for the innate immunity and the blood coagulation systems.
About this StructureAbout this Structure
1JC9 is a Single protein structure of sequence from Tachypleus tridentatus with NAG and CA as ligands. Full crystallographic information is available from OCA.
ReferenceReference
The 2.0-A crystal structure of tachylectin 5A provides evidence for the common origin of the innate immunity and the blood coagulation systems., Kairies N, Beisel HG, Fuentes-Prior P, Tsuda R, Muta T, Iwanaga S, Bode W, Huber R, Kawabata S, Proc Natl Acad Sci U S A. 2001 Nov 20;98(24):13519-24. Epub 2001 Nov 13. PMID:11707569
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