PDBsum entry: 1jc9

Sugar binding protein

PDB id: 1jc9

Contents

Protein chain

220 a.a. *

Ligands

NAG

Metals

_CA

Waters ×179

* Residue conservation analysis

PDB id:

1jc9

Name:

Sugar binding protein

Title:

Tachylectin 5a from tachypleus tridentatus (japanese horsesh

Structure:

Techylectin-5a. Chain: a

Source:

Tachypleus tridentatus. Organism_taxid: 6853

Biol. unit:

Tetramer (from PQS)

Resolution:

2.01Å R-factor: 0.183 R-free: 0.198

Authors:

N.Kairies,H.-G.Beisel,P.Fuentes-Prior,R.Tsuda,T.Muta,S.Iwana W.Bode,R.Huber,S.Kawabata

Key ref:

N.Kairies et al. (2001). The 2.0-A crystal structure of tachylectin 5A provides evidence for the common origin of the innate immunity and the blood coagulation systems. Proc Natl Acad Sci U S A, 98, 13519-13524. PubMed id: 11707569 DOI: 10.1073/pnas.201523798

Date:

08-Jun-01 Release date: 28-Nov-01

Protein chain

Q9U8W8  (TL5A_TACTR) -  Techylectin-5A

Seq: 292 a.a.

Struc: 220 a.a.

 Gene Ontology (GO) functional annotation 

• Cellular component: extracellular region (2 terms)
• Biological process: cell-cell adhesion (2 terms)
• Biochemical function: receptor binding (3 terms)

DOI no: 10.1073/pnas.201523798

Proc Natl Acad Sci U S A 98:13519-13524 (2001)

PubMed id: 11707569

The 2.0-A crystal structure of tachylectin 5A provides evidence for the common origin of the innate immunity and the blood coagulation systems.

N.Kairies, H.G.Beisel, P.Fuentes-Prior, R.Tsuda, T.Muta, S.Iwanaga, W.Bode, R.Huber, S.Kawabata.

ABSTRACT

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.

Selected figure(s)

Figure 2.
Fig. 2. Major functional sites within domain P of TL5A. (a) Stereo plot of the calcium-binding site. Oxygen atoms are represented in red and nitrogen atoms in blue. Water molecules are represented by red spheres. (b) Stereo view of the 2F[o-]-F[c] electron density map around the calcium ion. The map is contoured at 1 . Figure was prepared with BOBSCRIPT (29). (c) Structural basis of GlcNAc binding. Stereo view of the binding site, with relevant side chains labeled. Hydrogen bonds are indicated by yellow dashed lines and hydrophobic interactions by dotted green lines. Water molecules are represented by red spheres. Notice that the shortest hydrogen bond is formed between NH-atom of Cys-219 and the O atom of the GlcNAc acetamido group. (d) Stereo view of the 2F[o]-F[c] electron density map of the GlcNAc-binding site around the Arg-218-Cys-219 cis-peptide bond. The map is contoured at 1 .

Figure 3.
Fig. 3. Homology of TL5A and the chain fibrinogen fragment. (a) Superposition of the crystal structures of TL5A (gray) complexed with GlcNAc (white) and the chain fragment (yellow) complexed with GPRG-peptide (the A-knob, brown) (20). Ca^2+ ions are represented by spheres of the same color as the structure they belong. (b) Sequence alignment of TL5A-related sequences. Black numbers on top refer to the TL5A sequence, and green numbers below refer to the fibrinogen chain sequence. Closed blue triangles indicate residues involved in Ca^2+ binding. Orange stars indicate residues involved in GlcNAc (TL5A, above alignment), respectively A-knob binding ( chain fragment, below). Figure was prepared with ALSCRIPT (30).

Figures were selected by an automated process.