PDBsum entry 1rtm

Lectin

PDB id: 1rtm

Contents

Protein chains

149 a.a. *

Ligands

GOL ×15

Metals

_CA ×9

_CL ×3

Waters ×475

* Residue conservation analysis

PDB id:

1rtm

Name:

Lectin

Title:

Trimeric structure of a c-type mannose-binding protein

Structure:

Mannose-binding protein-a. Chain: 1, 2, 3. Engineered: yes

Source:

Rattus norvegicus. Norway rat. Organism_taxid: 10116.

Biol. unit:

Trimer (from PQS)

Resolution:

1.80Å R-factor: 0.220 R-free: 0.270

Authors:

W.I.Weis,K.Drickamer

Key ref:

W.I.Weis and K.Drickamer (1994). Trimeric structure of a C-type mannose-binding protein. Structure, 2, 1227-1240. PubMed id: 7704532 DOI: 10.1016/S0969-2126(94)00124-3

Date:

21-Nov-94 Release date: 07-Feb-95

Protein chains

P19999  (MBL1_RAT) -  Mannose-binding protein A from Rattus norvegicus

Seq: 238 a.a.

Struc: 149 a.a.

DOI no: 10.1016/S0969-2126(94)00124-3

Structure 2:1227-1240 (1994)

PubMed id: 7704532

Trimeric structure of a C-type mannose-binding protein.

W.I.Weis, K.Drickamer.

ABSTRACT

BACKGROUND: Mannose-binding proteins (MBPs) are C-type (Ca(2+)-dependent) animal lectins found in serum. They recognize cell-surface oligosaccharide structures characteristic of pathogenic bacteria and fungi, and trigger the neutralization of these organisms. Like most lectins, MBPs display weak intrinsic affinity for monovalent sugar ligands, but bind avidly to multivalent ligands. RESULTS: We report physical studies in solution and the crystal structure determined at 1.8 A Bragg spacings of a trimeric fragment of MBP-A, containing the carbohydrate-recognition domain (CRD) and the neck domain that links the carboxy-terminal CRD to the collagen-like portion of the intact molecule. The neck consists of a parallel triple-stranded coiled coil of alpha-helices linked by four residues to the CRD. The isolated neck peptide does not form stable helices in aqueous solution. The previously characterized carbohydrate-binding sites lie at the distal end of the trimer and are separated from each other by 53 A. CONCLUSIONS: The carbohydrate-binding sites in MBP-A are too far apart for a single trimer to bind multivalently to a typical mammalian high-mannose oligosaccharide. Thus MBPs can recognize pathogens selectively by binding avidly only to the widely spaced, repetitive sugar arrays on pathogenic cell surfaces. Sequence alignments reveal that other C-type lectins are likely to have a similar oligomeric structure, but differences in their detailed organization will have an important role in determining their interactions with oligosaccharides.

Selected figure(s)

Figure 7.
Figure 7. A portion of the neck–CRD interface, shown with the 1.25σ contour of the final 2F[o]–F[c] map. Conserved hydrophobic residues are labeled; the residues come from the protomer whose number precedes the amino acid name. Figure 7. A portion of the neck–CRD interface, shown with the 1.25σ contour of the final 2F[o]–F[c] map. Conserved hydrophobic residues are labeled; the residues come from the protomer whose number precedes the amino acid name.

Figure 8.
Figure 8. Representative sequences of the neck region and portions of the CRDs following the last Gly-X-Y repeat taken from various subgroups of collectins. RA, rat; HU, human. The a and d positions of the heptadrepeats are indicated. Sites of introns and the sites of subtilisin digestion that releases the carboxy-terminal CRDs of MBPs are underlined. Residues inthe neck–CRD interface (see Table 2) are denoted with asterisks. Sequences and intron positions are derived from [19, 44, 61, 62, 63, 64 and 65]. Figure 8. Representative sequences of the neck region and portions of the CRDs following the last Gly-X-Y repeat taken from various subgroups of collectins. RA, rat; HU, human. The a and d positions of the heptadrepeats are indicated. Sites of introns and the sites of subtilisin digestion that releases the carboxy-terminal CRDs of MBPs are underlined. Residues inthe neck–CRD interface (see [3]Table 2) are denoted with asterisks. Sequences and intron positions are derived from [[4]19, [5]44, [6]61, [7]62, [8]63, [9]64 and [10]65].

The above figures are reprinted by permission from Cell Press: Structure (1994, 2, 1227-1240) copyright 1994.

Figures were selected by an automated process.