Glycobiology Advance Access originally published online on April 28, 2004
Glycobiology 2004 14(8):693-700; doi:10.1093/glycob/cwh088
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Glycobiology vol. 14 no. 8 © Oxford University Press 2004; all rights reserved.
Arg343 in human surfactant protein D governs discrimination between glucose and N-acetylglucosamine ligands
4 Department of Medicine, National Jewish Medical and Research Center, 1400 Jackson Street, Denver, CO 80206; 5 Department of Chemical Engineering, Iowa State University, Ames, IA 50011; 6 Bioinformatics and Computational Biology Program, Iowa State University, Ames, IA 50011; 7 Department of Medicine, University of Colorado Health Sciences Center, Denver, CO 80262; and 8 Department of Biochemistry and Molecular Genetics, University of Colorado Health Sciences Center, Denver, CO 80262
Received on February 28, 2004; revised on April 15, 2004; accepted on April 16, 2004
Surfactant protein D (SP-D), one of the members of the collectin family of C-type lectins, is an important component of pulmonary innate immunity. SP-D binds carbohydrates in a calcium-dependent manner, but the mechanisms governing its ligand recognition specificity are not well understood. SP-D binds glucose (Glc) stronger than N-acetylglucosamine (GlcNAc). Structural superimposition of hSP-D with mannose- binding protein C (MBP-C) complexed with GlcNAc reveals steric clashes between the ligand and the side chain of Arg343 in hSP-D. To test whether Arg343 contributes to Glc > GlcNAc recognition specificity, we constructed a computational model of Arg343
Val (R343V) mutant hSP-D based on homology with MBP-C. Automated docking of 
-Me-Glc and -Me-GlcNAc into wild-type hSP-D and the R343V mutant of hSP-D suggests that Arg343 is critical in determining ligand-binding specificity by sterically prohibiting one binding orientation. To empirically test the docking predictions, an R343V mutant recombinant hSP-D was constructed. Inhibition analysis shows that the R343V mutant binds both Glc and GlcNAc with higher affinity than the wild-type protein and that the R343V mutant binds Glc and GlcNAc equally well. These data demonstrate that Arg343 is critical for hSP-D recognition specificity and plays a key role in defining ligand specificity differences between MBP and SP-D. Additionally, our results suggest that the number of binding orientations contributes to monosaccharide binding affinity.
1 Present address: Department of Cell Sciences, Amgen, Inc., 1201 Amgen Court West, Seattle, WA 98119
2 Present address: Department of Genetics, Stanford University, 300 Pasteur Drive, Stanford, CA 94305
3 To whom correspondence should be addressed; e-mail: voelkerd{at}njc.org
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  E. C. Crouch, K. Smith, B. McDonald, D. Briner, B. Linders, J. McDonald, U. Holmskov, J. Head, and K. Hartshorn Species Differences in the Carbohydrate Binding Preferences of Surfactant Protein D Am. J. Respir. Cell Mol. Biol., July 1, 2006; 35(1): 84 - 94. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. Nadesalingam, A. W. Dodds, K. B. M. Reid, and N. Palaniyar Mannose-Binding Lectin Recognizes Peptidoglycan via the N-Acetyl Glucosamine Moiety, and Inhibits Ligand-Induced Proinflammatory Effect and Promotes Chemokine Production by Macrophages J. Immunol., August 1, 2005; 175(3): 1785 - 1794. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 E. Crouch, Y. Tu, D. Briner, B. McDonald, K. Smith, U. Holmskov, and K. Hartshorn Ligand Specificity of Human Surfactant Protein D: EXPRESSION OF A MUTANT TRIMERIC COLLECTIN THAT SHOWS ENHANCED INTERACTIONS WITH INFLUENZA A VIRUS J. Biol. Chem., April 29, 2005; 280(17): 17046 - 17056. [Abstract] [Full Text] [PDF]
|
|