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The Carbohydrate Recognition Domain of Surfactant Protein A Mediates Binding to the Major Surface Glycoprotein of Pneumocystis carinii
- Source :
- Biochemistry. 36:8092-8099
- Publication Year :
- 1997
- Publisher :
- American Chemical Society (ACS), 1997.
-
Abstract
- Pneumocystis carinii is a common cause of life-threatening pneumonia in immunodeficient patients. Pulmonary surfactant protein A (SP-A), an alveolar glycoprotein containing collagen-like and carbohydrate recognition domains (CRD), binds P. carinii and enhances adherence to alveolar macrophages. In this study, we examined the structural basis of the interaction between SP-A and the major surface glycoprotein of P. carinii (MSG). Rat SP-A bound to purified rat P. carinii-derived MSG in a saturable and calcium-dependent manner, which was partially reversible by coincubation with excess monosaccharides, or pretreatment of MSG with N-glycanase. Mutant recombinant SP-As with neutral amino acid substitutions for the predicted calcium- and carbohydrate-coordinating residues of the CRD were synthesized in insect cells using baculovirus vectors and tested for binding to MSG. Substitutions of negatively charged (Glu195, Glu202, and Asp215) and polar residues (Asn214) of the CRD with alanine but not substitution of the Arg197 with glycine reduced the binding of SP-A to mannose-Sepharose beads and to MSG. Deletion of the N-linked oligosaccharides from SP-A by mutagenesis of the consensus sequences for glycosylation had no effect on binding. We conclude that the CRD mediates the binding of SP-A to oligosaccharides attached to MSG.
- Subjects :
- Pulmonary Surfactant-Associated Proteins
Glycosylation
Proteolipids
Oligosaccharides
Plasma protein binding
Biology
Biochemistry
Fungal Proteins
Rats, Sprague-Dawley
chemistry.chemical_compound
Animals
Binding site
Pulmonary Surfactant-Associated Protein A
Alanine
chemistry.chemical_classification
Binding Sites
Membrane Glycoproteins
Pneumocystis
Pulmonary Surfactants
Recombinant Proteins
Protein Structure, Tertiary
Rats
Surfactant protein A
chemistry
Pneumocystis carinii
Mutagenesis, Site-Directed
Glycoprotein
Protein Binding
Subjects
Details
- ISSN :
- 15204995 and 00062960
- Volume :
- 36
- Database :
- OpenAIRE
- Journal :
- Biochemistry
- Accession number :
- edsair.doi.dedup.....af39b47179584b11e61490c1d93858a9