1TL2

TACHYLECTIN-2 FROM TACHYPLEUS TRIDENTATUS (JAPANESE HORSESHOE CRAB)

Summary for 1TL2

• Entry DOI: 10.2210/pdb1tl2/pdb
• Descriptor: PROTEIN (TACHYLECTIN-2), 2-acetamido-2-deoxy-alpha-D-glucopyranose (3 entities in total)
• Functional Keywords: animal lectin, horseshoe crab, n-acetylglucosamine, beta-propeller, sugar binding protein
• Biological source: Tachypleus tridentatus
• Cellular location: Secreted : Q27084
• Total number of polymer chains: 1
• Total formula weight: 27931.98

Authors

Beisel, H.-G.,Kawabata, S.,Iwanaga, S.,Huber, R.,Bode, W. (deposition date: 1998-12-14, release date: 1999-12-15, Last modification date: 2023-12-27)

Primary citation

Beisel, H.G.,Kawabata, S.,Iwanaga, S.,Huber, R.,Bode, W.
Tachylectin-2: crystal structure of a specific GlcNAc/GalNAc-binding lectin involved in the innate immunity host defense of the Japanese horseshoe crab Tachypleus tridentatus.
EMBO J., 18:2313-2322, 1999

PubMed Abstract: Tachylectin-2, isolated from large granules of the hemocytes of the Japanese horseshoe crab (Tachypleus tridentatus), is a 236 amino acid protein belonging to the lectins. It binds specifically to N-acetylglucosamine and N-acetylgalactosamine and is a part of the innate immunity host defense system of the horseshoe crab. The X-ray structure of tachylectin-2 was solved at 2.0 A resolution by the multiple isomorphous replacement method and this molecular model was employed to solve the X-ray structure of the complex with N-acetylglucosamine. Tachylectin-2 is the first protein displaying a five-bladed beta-propeller structure. Five four-stranded antiparallel beta-sheets of W-like topology are arranged around a central water-filled tunnel, with the water molecules arranged as a pentagonal dodecahedron. Tachylectin-2 exhibits five virtually identical binding sites, one in each beta-sheet. The binding sites are located between adjacent beta-sheets and are made by a large loop between the outermost strands of the beta-sheets and the connecting segment from the previous beta-sheet. The high number of five binding sites within the single polypeptide chain strongly suggests the recognition of carbohydrate surface structures of pathogens with a fairly high ligand density. Thus, tachylectin-2 employs strict specificity for certain N-acetyl sugars as well as the surface ligand density for self/non-self recognition.

PubMed: 10228146
DOI: 10.1093/emboj/18.9.2313

Experimental method

X-RAY DIFFRACTION (2 Å)