Role of N-Linked Glycosylation in Human Osteonectin

Xie, Ronglin; Long, George L.

doi:10.1074/jbc.270.39.23212

Cited by 28 publications

(22 citation statements)

References 39 publications

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“…The ⌬I-N99Q mutant showed only an insignificant change in the binding to collagen I and IV and an ϳ8-fold loss in its affinity for collagen V (Table IV). A similar mutation in another BM-40 fragment was previously shown to enhance binding to collagen V (13). DISCUSSION Application of a surface plasmon resonance assay demonstrated a remarkably similar affinity of BM-40 for four different collagen types including several that form larger interstitial fibrils (I, III, and V) or networks in basement membranes (IV).…”

Section: Binding Of Bm-40 and Its Ec Module To Different Collagensupporting

confidence: 55%

“…However, further factors may modulate collagen affinities as indicated in studies with BM-40 obtained from human bone and platelets which differed considerably in their binding to collagen V and in their N-linked oligosaccharides being either of the mannose-rich or complex type (11). This indicated involvement in collagen V binding of the FS module containing these sites as also shown by deglycosylation achieved either enzymatically or by mutation (13). This study also provided evidence that the N-terminal domain I and/or the FS module are essential for binding which was subsequently restricted to an N-terminal 17-residue segment in a synthetic and recombinant analysis (14).…”

supporting

confidence: 64%

“…Collagen V binding was also shown for a recombinant human BM-40 fragment lacking the EC module (13,14). In these studies prevention of N-glycosylation by an N99Q mutation increased, and deletions in the N-terminal domain I abolished collagen V binding.…”

Section: Effect Of N-glycosylation On Collagen Binding-previousmentioning

confidence: 80%

“…(Table IV). Mutant ⌬I was therefore used to introduce a single N99Q mutation previously shown to prevent N-glycosylation (13). The purified mutant ⌬I-N99Q was slightly faster in electrophoretic mobility than ⌬I, and its glucosamine content was reduced from 4.1 residues to less than 0.5 residues consistent with the lack of N-glycosylation.…”

Section: Binding Of Bm-40 and Its Ec Module To Different Collagenmentioning

confidence: 99%

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Limited Cleavage of Extracellular Matrix Protein BM-40 by Matrix Metalloproteinases Increases Its Affinity for Collagens

Sasaki

Göhring

Mann

et al. 1997

Journal of Biological Chemistry

139

121

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The 33-kDa matrix protein BM-40 (SPARC, osteonectin) consists of an acidic N-terminal domain I, a central cysteine-rich follistatin-like module, and a C-terminal extracellular calcium-binding (EC) module. Previous studies attributed collagen IV and high affinity calcium binding of BM-40 to its EC module, which was shown by x-ray crystallography to consist of an EF-hand pair surrounded by several ␣-helical and loop segments. This module was now shown by surface plasmon resonance assay to bind with similar affinities to collagens I, III, and V. Cleavage of recombinant BM-40 and its EC module by collagenase-3, gelatinases A and B, matrilysin, and stromelysin-1 showed similar fragment patterns, whereas collagenase-1 was inactive. Some differences were, however, observed in cleavage rates and the preference of certain cleavage sites. Edman degradation of fragments demonstrated only three to four major cleavage sites in the central region of domain I and a single uniform cleavage in helix C of the EC module. Cleavage is accompanied by a 7-20-fold increase in binding activity for collagens I, IV, and V but revealed only small effects on calcium-dependent ␣-helical changes in the EC module. The data were interpreted to indicate that helix C cleavage is mainly responsible for enhancing collagen affinity by exposing the underlying helix A of the EC module. A similar activation may also occur in situ as indicated previously for tissue-derived BM-40.The small calcium-binding glycoprotein (33 kDa) referred to as BM-40, SPARC, or osteonectin has been shown to have a widespread occurrence in extracellular matrices of various organs with a particularly high expression found during morphogenesis, tissue remodeling, and repair. The protein exhibits anti-adhesive properties in cell culture and modulates the expression of certain extracellular receptors. Several extracellular ligands have been identified for BM-40 including some collagen types and cytokines (1). This indicated various binding sites on BM-40 in agreement with a previous proposal of a mosaic structure for the protein (2). The most recent interpretation of the domain structure based on recombinant deletion mutants and a crystal structure of a fragment encompassing the C-terminal 150 residues (3, 4) demonstrated an acidic and flexible N-terminal domain I (ϳ50 residues) followed by a follistatin-like (FS) 1 module (ϳ75 residues) and a novel extracellular calcium-binding (EC) module (ϳ150 residues). X-ray crystallography of this EC module demonstrated two opposing calcium-binding EF hands, as found in many intracellular proteins (5), which were in close contact to an extended ␣ helix (4). A combination of adjacent FS and EC modules has been detected in the cDNA sequences of several more extracellular proteins suggesting the existence of a protein family (1, 3, 4). Yet it is not known so far whether they are functionally related to BM-40.The binding of BM-40 to the fibril-forming collagens I, III, and V and basement membrane collagen IV has been demonstrated and depended ...

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Section: Binding Of Bm-40 and Its Ec Module To Different Collagensupporting

confidence: 55%

supporting

confidence: 64%

Section: Effect Of N-glycosylation On Collagen Binding-previousmentioning

confidence: 80%

Section: Binding Of Bm-40 and Its Ec Module To Different Collagenmentioning

confidence: 99%

See 2 more Smart Citations

Limited Cleavage of Extracellular Matrix Protein BM-40 by Matrix Metalloproteinases Increases Its Affinity for Collagens

Sasaki

Göhring

Mann

et al. 1997

Journal of Biological Chemistry

139

121

View full text Add to dashboard Cite

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“…Using these antibodies, a variable degree of cleavage was detected in SPARC obtained from several adult mouse tissues, suggesting this cleavage to be a physiological mechanism of modulating collagen binding. There is evidence that the N-glycan at Asn-99 also modulates the binding affinity for collagen (31)(32)(33), but the mechanism remains to be elucidated.…”

mentioning

confidence: 99%

Mapping of SPARC/BM-40/Osteonectin-binding Sites on Fibrillar Collagens

Giudici

Raynal

Wiedemann

et al. 2008

Journal of Biological Chemistry

100

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The 33-kDa matrix protein SPARC (BM-40, osteonectin) binds several collagen types with moderate affinity. The collagen-binding site resides in helix ␣A of the extracellular calciumbinding domain of SPARC and is partially masked by helix ␣C. Previously, we found that the removal of helix ␣C caused a 10-fold increase in the affinity of SPARC for collagen, and we identified amino acids crucial for binding by site-directed mutagenesis. In this study, we used rotary shadowing, CNBr peptides, and synthetic peptides to map binding sites of SPARC onto collagens I, II, and III. Rotary shadowing and electron microscopy of SPARC-collagen complexes identified a major binding site ϳ180 nm from the C terminus of collagen. SPARC binding was also detected with lower frequency near the matrix metalloproteinase cleavage site. These data fit well with our analysis of SPARC binding to CNBr peptides, denaturation of which abolished binding, indicating triple-helical conformation of collagen to be essential. SPARC binding was substantially decreased in two of seven ␣2(I) mutant procollagen I samples and after N-acetylation of Lys/Hyl side chains in wild-type collagen. Synthetic peptides of collagen III were used to locate the binding sites, and we found SPARC binding activity in a synthetic triple-helical peptide containing the sequence GPOG-PSGPRGQOGVMGFOGPKGNDGAO (where O indicates 4-hydroxyproline), with affinity for SPARC comparable with that of procollagen III. This sequence is conserved among ␣ chains of collagens I, II, III, and V. In vitro collagen fibrillogenesis was delayed in the presence of SPARC, suggesting that SPARC might modulate collagen fibril assembly in vivo.Collagens are major components of the extracellular matrix, comprising ϳ30% of the protein mass of vertebrates. At least 28 collagens have been identified so far (1-3) encoded by 46 separate genes. The defining feature of collagens is a triple-helical domain assembled from three polypeptide strands, called ␣-chains, which each consist of repeating Gly-X-Y sequences, where X is often proline and Y is often hydroxyproline. This primary structure facilitates left-handed poly-proline II helical conformation in each ␣-chain, and three ␣-chains form a righthanded triple helix stabilized by interchain hydrogen bonds (4). To form this structure, Gly is required as every third residue. Its lack of side chains allows contact between ␣-chains, whereas the side chains of residues X and Y are exposed on the surface of the triple helix where they can interact with various molecules. Collagens are major structural proteins, endowing mechanical strength upon the extracellular matrix and also regulating cell behavior through the binding of cell surface receptors and other proteins, such as discoidin domain receptors, a subset of the integrins ␣1␤1, ␣2␤1, ␣10␤1, and ␣11␤1, NG2 proteoglycan, and many matrix molecules (5-7). Nearly 50 different ligands have been shown to interact with collagen, and the binding sites for half of these have been mapped onto collagen I (8). The bind...

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Basement Membrane ProteinBM‐40

Hohenester

Timpl

2004

Handbook of Metalloproteins

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BM‐40, also known as SPARC or osteonectin, is a secreted glycoprotein present in all metazoa. The protein is expressed in tissues undergoing morphogenesis, remodeling, and repair. In vitro , BM‐40 binds to several collagens and is both antiproliferative and counteradhesive. Human BM‐40 consists of an acidic N‐terminal domain, a follistatin‐like (FS) domain, and an α‐helical (EC) domain that contains two functional EF‐hand calcium‐binding motifs. The crystal structure of the FS–EC domain pair has been determined. Calcium and collagen binding to the EC domain has been studied using site‐directed mutagenesis, spectroscopy, and binding assays.

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Role of N-Linked Glycosylation in Human Osteonectin

Cited by 28 publications

References 39 publications

Limited Cleavage of Extracellular Matrix Protein BM-40 by Matrix Metalloproteinases Increases Its Affinity for Collagens

Limited Cleavage of Extracellular Matrix Protein BM-40 by Matrix Metalloproteinases Increases Its Affinity for Collagens

Mapping of SPARC/BM-40/Osteonectin-binding Sites on Fibrillar Collagens

Basement Membrane ProteinBM‐40

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