5FFT image
Entry Detail
PDB ID:
5FFT
Title:
Crystal Structure of Surfactant Protein-A Y221A Mutant
Biological Source:
Source Organism:
Host Organism:
PDB Version:
Deposition Date:
2015-12-18
Release Date:
2016-07-06
Method Details:
Experimental Method:
Resolution:
2.20 Å
R-Value Free:
0.20
R-Value Work:
0.16
R-Value Observed:
0.17
Space Group:
P 63
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Pulmonary surfactant-associated protein A
Mutations:N187S/Y221A
Chain IDs:A
Chain Length:148
Number of Molecules:1
Biological Source:Rattus norvegicus
Modified Residue
Compound ID Chain ID Parent Comp ID Details 2D Image
SME A MET modified residue
Ligand Molecules
Primary Citation
Elucidation of Lipid Binding Sites on Lung Surfactant Protein A Using X-ray Crystallography, Mutagenesis, and Molecular Dynamics Simulations.
Biochemistry 55 3692 3701 (2016)
PMID: 27324153 DOI: 10.1021/acs.biochem.6b00048

Abstact

Surfactant protein A (SP-A) is a collagenous C-type lectin (collectin) that is critical for pulmonary defense against inhaled microorganisms. Bifunctional avidity of SP-A for pathogen-associated molecular patterns (PAMPs) such as lipid A and for dipalmitoylphosphatidylcholine (DPPC), the major component of surfactant membranes lining the air-liquid interface of the lung, ensures that the protein is poised for first-line interactions with inhaled pathogens. To improve our understanding of the motifs that are required for interactions with microbes and surfactant structures, we explored the role of the tyrosine-rich binding surface on the carbohydrate recognition domain of SP-A in the interaction with DPPC and lipid A using crystallography, site-directed mutagenesis, and molecular dynamics simulations. Critical binding features for DPPC binding include a three-walled tyrosine cage that binds the choline headgroup through cation-π interactions and a positively charged cluster that binds the phosphoryl group. This basic cluster is also critical for binding of lipid A, a bacterial PAMP and target for SP-A. Molecular dynamics simulations further predict that SP-A binds lipid A more tightly than DPPC. These results suggest that the differential binding properties of SP-A favor transfer of the protein from surfactant DPPC to pathogen membranes containing appropriate lipid PAMPs to effect key host defense functions.

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Primary Citation of related structures