Orientation of Bound Ligands in Mannose-binding Proteins

Mannose-binding proteins (MBPs) are C-type animal lectins that recognize high mannose oligosaccharides on pathogenic cell surfaces. MBPs bind to their carbohydrate ligands by forming a series of Ca2+ coordination and hydrogen bonds with two hydroxyl groups equivalent to the 3- and 4-OH of mannose. In this work, the determinants of the orientation of sugars bound to rat serum and liver MBPs (MBP-A and MBP-C) have been systematically investigated. The crystal structures of MBP-A soaked with monosaccharides and disaccharides and also the structure of the MBP-A trimer cross-linked by a high mannose asparaginyl oligosaccharide reveal that monosaccharides or α1–6-linked mannose bind to MBP-A in one orientation, whereas α1–2- or α1–3-linked mannose binds in an orientation rotated 180° around a local symmetry axis relating the 3- and 4-OH groups. In contrast, a similar set of ligands all bind to MBP-C in a single orientation. The mutation of MBP-A His189 to its MBP-C equivalent, valine, causes Manα1–3Man to bind in a mixture of orientations. These data combined with modeling indicate that the residue at this position influences the orientation of bound ligands in MBP. We propose that the control of binding orientation can influence the recognition of multivalent ligands. A lateral association of trimers in the cross-linked crystals may reflect interactions within higher oligomers of MBP-A that are stabilized by multivalent ligands.

[1]  K. Drickamer,et al.  Ligand-binding characteristics of rat serum-type mannose-binding protein (MBP-A). Homology of binding site architecture with mammalian and chicken hepatic lectins. , 1991, The Journal of biological chemistry.

[2]  A. Tauber,et al.  Characterization of two mannose-binding protein cDNAs from rhesus monkey (Macaca mulatta): structure and evolutionary implications. , 1996, Glycobiology.

[3]  T. Kawasaki,et al.  Serum lectin with known structure activates complement through the classical pathway. , 1987, The Journal of biological chemistry.

[4]  S. Sheriff,et al.  Human mannose-binding protein carbohydrate recognition domain trimerizes through a triple α-helical coiled-coil , 1994, Nature Structural Biology.

[5]  R. Wallis,et al.  Asymmetry adjacent to the collagen-like domain in rat liver mannose-binding protein. , 1997, The Biochemical journal.

[6]  Wayne A. Hendrickson,et al.  Structure of a C-type mannose-binding protein complexed with an oligosaccharide , 1992, Nature.

[7]  A. Brunger Free R value: a novel statistical quantity for assessing the accuracy of crystal structures. , 1992 .

[8]  R J Read,et al.  Crystallography & NMR system: A new software suite for macromolecular structure determination. , 1998, Acta crystallographica. Section D, Biological crystallography.

[9]  M. Turner,et al.  The level of mannan‐binding protein regulates the binding of complement‐derived opsonins to mannan and zymosan at low serum concentrations , 1990, Clinical and experimental immunology.

[10]  R. Wallis,et al.  Molecular Determinants of Oligomer Formation and Complement Fixation in Mannose-binding Proteins* , 1999, The Journal of Biological Chemistry.

[11]  Z. Otwinowski,et al.  [20] Processing of X-ray diffraction data collected in oscillation mode. , 1997, Methods in enzymology.

[12]  W. Weis,et al.  Trimeric structure of a C-type mannose-binding protein. , 1994, Structure.

[13]  J. Thornton,et al.  PROCHECK: a program to check the stereochemical quality of protein structures , 1993 .

[14]  R. Lee,et al.  Difference in the binding mode of two mannose-binding proteins: demonstration of a selective minicluster effect. , 1997, Biochemistry.

[15]  A. Tenner,et al.  Mannose binding protein (MBP) enhances mononuclear phagocyte function via a receptor that contains the 126,000 M(r) component of the C1q receptor. , 1995, Immunity.

[16]  R. Dwek,et al.  A statistical analysis of N- and O-glycan linkage conformations from crystallographic data. , 1999, Glycobiology.

[17]  A T Brünger,et al.  Protein hydration observed by X-ray diffraction. Solvation properties of penicillopepsin and neuraminidase crystal structures. , 1994, Journal of molecular biology.

[18]  W. Hendrickson,et al.  Description of Overall Anisotropy in Diffraction from Macromolecular Crystals , 1987 .

[19]  Yuan-chuan Lee,et al.  Difference in binding-site architecture of the serum-type and liver-type mannose-binding proteins , 1997, Glycoconjugate Journal.

[20]  K. Joiner,et al.  The human mannose-binding protein functions as an opsonin , 1989, The Journal of experimental medicine.

[21]  Axel T. Brunger,et al.  Extension of molecular replacement: a new search strategy based on Patterson correlation refinement , 1990 .

[22]  K. Drickamer,et al.  Differential recognition of core and terminal portions of oligosaccharide ligands by carbohydrate-recognition domains of two mannose-binding proteins. , 1990, The Journal of biological chemistry.

[23]  William I. Weis,et al.  Structural Analysis of Monosaccharide Recognition by Rat Liver Mannose-binding Protein (*) , 1996, The Journal of Biological Chemistry.

[24]  R. Dwek,et al.  Binding of sugar ligands to Ca(2+)-dependent animal lectins. I. Analysis of mannose binding by site-directed mutagenesis and NMR. , 1994, The Journal of biological chemistry.

[25]  K. Drickamer,et al.  Mannose-binding proteins isolated from rat liver contain carbohydrate-recognition domains linked to collagenous tails. Complete primary structures and homology with pulmonary surfactant apoprotein. , 1986, The Journal of biological chemistry.

[26]  W. Weis,et al.  The C‐type lectin superfamily in the immune system , 1998, Immunological reviews.

[27]  R. Wallis,et al.  Stoichiometry of Complexes between Mannose-binding Protein and Its Associated Serine Proteases , 2001, The Journal of Biological Chemistry.

[28]  R. Dwek,et al.  The high degree of internal flexibility observed for an oligomannose oligosaccharide does not alter the overall topology of the molecule. , 1998, European journal of biochemistry.