PDBsum entry 2ggu

Sugar binding protein

PDB id: 2ggu

Contents

Protein chain

151 a.a. *

Ligands

GLC-GLC-GLC ×3

Metals

_CA ×9

Waters ×275

* Residue conservation analysis

PDB id:

2ggu

Name:

Sugar binding protein

Title:

Crystal structure of the trimeric neck and carbohydrate recognition domain of human surfactant protein d in complex with maltotriose

Structure:

Pulmonary surfactant-associated protein d. Chain: a, b, c. Fragment: trimeric neck and carbohydrate recognition domain. Synonym: sp-d, psp-d. Engineered: yes

Source:

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

Biol. unit:

Trimer (from PQS)

Resolution:

1.90Å R-factor: 0.221 R-free: 0.248

Authors:

J.F.Head

Key ref:

E.Crouch et al. (2006). Contributions of phenylalanine 335 to ligand recognition by human surfactant protein D: ring interactions with SP-D ligands. J Biol Chem, 281, 18008-18014. PubMed id: 16636058 DOI: 10.1074/jbc.M601749200

Date:

24-Mar-06 Release date: 02-May-06

Protein chains

P35247  (SFTPD_HUMAN) -  Pulmonary surfactant-associated protein D from Homo sapiens

Seq: 375 a.a.

Struc: 151 a.a.

DOI no: 10.1074/jbc.M601749200

J Biol Chem 281:18008-18014 (2006)

PubMed id: 16636058

Contributions of phenylalanine 335 to ligand recognition by human surfactant protein D: ring interactions with SP-D ligands.

E.Crouch, B.McDonald, K.Smith, T.Cafarella, B.Seaton, J.Head.

ABSTRACT

Surfactant protein D (SP-D) is an innate immune effector that contributes to antimicrobial host defense and immune regulation. Interactions of SP-D with microorganisms and organic antigens involve binding of glycoconjugates to the C-type lectin carbohydrate recognition domain (CRD). A trimeric fusion protein encoding the human neck+CRD bound to the aromatic glycoside p-nitrophenyl-alpha-D-maltoside with nearly a log-fold higher affinity than maltose, the prototypical competitor. Maltotriose, which has the same linkage pattern as the maltoside, bound with intermediate affinity. Site-directed substitution of leucine for phenylalanine 335 (Phe-335) decreased affinities for the maltoside and maltotriose without significantly altering the affinity for maltose or glucose, and substitution of tyrosine or tryptophan for leucine restored preferential binding to maltotriose and the maltoside. A mutant with alanine at this position failed to bind to mannan or maltose-substituted solid supports. Crystallographic analysis of the human neck+CRD complexed with maltotriose or p-nitrophenyl-maltoside showed stacking of the terminal glucose or nitrophenyl ring with the aromatic ring of Phe-335. Our studies indicate that Phe-335, which is evolutionarily conserved in all known SP-Ds, plays important, if not critical, roles in SP-D function.

Selected figure(s)

Figure 5.
FIGURE 5. Crystal structure of trimeric NCRD bound to maltotriose. Ribbon representation of protein viewed perpendicular to axis of neck domain, each subunit colored differently. Maltotriose is shown as a ball-and-stick model and calcium ions as green spheres. Maltotriose is bound in the same orientation in each subunit. However, the interaction of the trisaccharide with calcium ion 1 and the binding surface is most clearly shown in the cyan subunit at left.

Figure 8.
FIGURE 8. Superimposition of maltose and maltotriose bound to the SP-D CRD. The protein model shows the maltotriose complex. Maltose is shown as a green stick model (with rings labeled G1–2 in green) and maltotriose as a magenta stick model (with rings labeled G1–3 in magenta). The maltose was aligned by least squares superimposition of residues in this region using the structure of Protein Data Bank accession number 1PWB. Some of the hydrogen bonds between protein and maltotriose are shown by green dashed lines.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2006, 281, 18008-18014) copyright 2006.

Figures were selected by an automated process.