Differential interactions of decorin and decorin mutants with type I and type VI collagens.
The small leucine-rich proteoglycan decorin can bind via its core protein to different types of collagens such as type I and type VI. To test whether decorin can act as a bridging molecule between these collagens, the binding properties of wild-type decorin, two full-length decorin species with single amino acid substitutions (DCN E180K, DCN E180Q), which previously showed reduced binding to collagen type I fibrils, and a truncated form of decorin (DCN Q153) to the these collagens were investigated. In a solid phase assay dissociation constants for wild-type decorin bound to methylated, therefore monomeric, triple helical type I collagen were in the order of 10(-10) m, while dissociation constants for fibrillar type I collagen were approximately 10(-9) m. The dissociation constant for type VI was approximately 10(-7) m. Using real-time analysis for a more detailed investigation DCN E180Q and DCN E180K exhibited lower association and higher dissociation constants to type I collagen, compared to wild-type decorin, deviating by at least one order of magnitude. In contrast, the affinities of these mutants to type VI collagen were 10 times higher than the affinity of wild-type decorin (K(D) approximately 10(-8) m). Further investigations verified that complexes of type VI collagen and decorin bound type I collagen and that the affinity of collagen type VI to type I was increased by the presence of decorin. These data show that decorin not only can regulate collagen fibril formation but that it also can act as an intermediary between type I and type VI collagen and that these two types of collagen interact via different binding sites.
Departement of Physiological Chemistry and Pathobiochemistry, University Hospital of Münster, Germany.
Gordon
G
Nareyeck
Daniela G
DG
Seidler
David
D
Troyer
Jürgen
J
Rauterberg
Hans
H
Kresse
Elke
E
Schönherr
D000818:Animals; D001665:Binding Sites; D002417:Cattle; D002460:Cell Line; D002942:Circular Dichroism; D024042:Collagen Type I / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism* / Q000648:ultrastructure; D024142:Collagen Type VI / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism* / Q000648:ultrastructure; D058575:Decorin; D016326:Extracellular Matrix Proteins; D015870:Gene Expression; D018698:Glutamic Acid / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008854:Microscopy, Electron; D009154:Mutation / Q000235:genetics*; D011485:Protein Binding; D011509:Proteoglycans / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D020349:Surface Plasmon Resonance
D024042:Collagen Type I; D024142:Collagen Type VI; C546878:DCN protein, human; D058575:Decorin; D016326:Extracellular Matrix Proteins; D011509:Proteoglycans; D018698:Glutamic Acid