PDBsum entry: 1htn

Lectin

PDB-id: 1htn

Asymmetric unit

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Description

Header details

Header records

References

PROCHECK

Protein chain

156 a.a. *

Metal ions

_CA ×2

Waters ×36

* Residue conservation analysis

Tools

Clefts Calculation

Biological unit, trimer
- as defined in PDB file (see also PQS)

PDB id:

1htn

Name:

Lectin

Title:

Human tetranectin, a trimeric plasminogen binding protein with an alpha-helical coiled coil

Structure:

Tetranectin. Chain: a. Fragment: residues 26 - 181. Engineered: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Expressed in: escherichia coli. Expression_system_taxid: 562.

Biological unit:

Homo-tetramer (from PDB file)

UniProt:

P05452 (TETN_HUMAN)

Seq:

202 a.a.

Struc:

156 a.a.*

Key:	PfamA domain
Secondary structure	CATH domain

* PDB and UniProt seqs differ at 1 residue position (black cross)

Resolution:

2.80Å

R-factor:

0.223

R-free:

0.292

Authors:

B.B.Nielsen,J.S.Kastrup,H.Rasmussen,T.L.Holtet, J.H.Graversen,M.Etzerodt,H.C.Thogersen,I.K.Larsen

Key ref:

B.B.Nielsen et al. (1997). Crystal structure of tetranectin, a trimeric plasminogen-binding protein with an alpha-helical coiled coil.. FEBS Lett, 412, 388-396. [PubMed id: 9256258] [DOI: 10.1016/S0014-5793(97)00664-9]

Date:

28-May-97

Release date:

03-Dec-97

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Clefts

Surface

Key reference

DOI no: 10.1016/S0014-5793(97)00664-9

FEBS Lett 412:388-396 (1997)

PubMed id: 9256258

Crystal structure of tetranectin, a trimeric plasminogen-binding protein with an alpha-helical coiled coil.

B.B.Nielsen, J.S.Kastrup, H.Rasmussen, T.L.Holtet, J.H.Graversen, M.Etzerodt, H.C.Thøgersen, I.K.Larsen.

ABSTRACT

Tetranectin is a plasminogen kringle 4-binding protein. The crystal structure has been determined at 2.8 A resolution using molecular replacement. Human tetranectin is a homotrimer forming a triple alpha-helical coiled coil. Each monomer consists of a carbohydrate recognition domain (CRD) connected to a long alpha-helix. Tetranectin has been classified in a distinct group of the C-type lectin superfamily but has structural similarity to the proteins in the group of collectins. Tetranectin has three intramolecular disulfide bridges. Two of these are conserved in the C-type lectin superfamily, whereas the third is present only in long-form CRDs. Tetranectin represents the first structure of a long-form CRD with intact calcium-binding sites. In tetranectin, the third disulfide bridge tethers the CRD to the long helix in the coiled coil. The trimerization of tetranectin as well as the fixation of the CRDs relative to the helices in the coiled coil indicate a demand for high specificity in the recognition and binding of ligands.

Selected figure(s)

Figure 1.
Fig. 1. a: Overall structure of the TN monomer. TN consists of a long α-helix (E2) and a carbohydrate recognition domain (CRD). The two calcium ions are illustrated as yellow spheres, and the three disulfide bridges: 1 (Cys^50-Cys^60), 2 (Cys^77-Cys^176), and 3 (Cys^152-Cys^168), are shown in a ball and stick representation. b: Superposition of the CRDs of human TN (in yellow), human lithostathine (in blue), human MBP (in green), and human E-selectin (in orange). Calcium ions at site 1 and 2 are illustrated as spheres, and the three disulfide bridges in ball and stick. The r.m.s. deviation between TN and lithostathine is 1.5 Å (for 116 Cα atoms), between TN and human MBP 1.2 Å (for 117 Cα atoms), and between TN and human E-selectin 1.3 Å (for 104 Cα atoms). c-d: The overall structure of the TN trimer viewed (c) along and (d) perpendicular to the 3-fold axis. The figures were generated using MOLSCRIPT [39].

Figure 2.
Fig. 2. a: Stereo drawing of the triple α-helical coiled coil of TN viewed perpendicular to the 3-fold axis. The amino acid side chains in a and d positions of the heptad repeats (Leu^26, Leu^30, Leu^33, Val^37, Leu^40, Gln^44, Gln^47 and Leu^51) are shown in ball and stick. b-c: Superimposition of the helices of the coiled coil in TN (in yellow), in rat MBP from serum (in red) and in human MBP (in green), viewed (c) along and (b) perpendicular to the 3-fold axis. The helices were aligned according to the heptad repeats (Table 2). Calcium ions at site 1 and 2 are illustrated as spheres. d: One monomer of each protein, superimposed as in (b-c), illustrating the relative orientation of the CRDs with respect to the helices. The figures were generated using MOLSCRIPT [39].

The above figures are reprinted by permission from the Federation of European Biochemical Societies: FEBS Lett (1997, 412, 388-396) copyright 1997.