Critical role of glutamate in a central leucine-rich repeat of decorin for interaction with type I collagen.
The chondroitin/dermatan sulfate proteoglycan decorin is known to interact via its core protein with fibrillar collagens, thereby influencing the kinetics of fibril formation and the final diameter of the fibrils. To define the binding site(s) for type I collagen along the core protein, which is mainly composed of leucine-rich repeat structures, decorin cDNAs were constructed and expressed in human kidney 293 cells. The constructs encoded (i) C-terminally truncated molecules, (ii) core proteins with deletions of selected leucine-rich repeats, or (iii) various point mutations. The deletion of the sixth leucine-rich repeat Met176-Lys201 and the mutation E180K drastically interfered with the binding to reconstituted type I collagen fibrils. In contrast, the deletion of the seventh repeat Leu202-Ser222 led at the most to a marginally impaired binding, although the secretion of this proteoglycan was abnormally low. Decorin with two other point mutations in the sixth leucine-rich repeat, Lys187 --> Gln and Lys200 --> Gln, respectively, bound type I collagen either normally or even better than the normal recombinant proteoglycan. These data suggest that a major collagen-binding site of decorin is located within the sixth leucine-rich repeat and that glutamate-180 within this repeat is of special importance for ionic interactions between the two matrix components.
Kresse
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Institute of Physiological Chemistry and Pathobiochemistry, University of Münster, D-48149 Münster, Germany. kresse@uni-muenster.de
Liszio
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Schönherr
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Fisher
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D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D003094:Collagen / Q000378:metabolism*; D018076:DNA, Complementary; D058575:Decorin; D016326:Extracellular Matrix Proteins; D018698:Glutamic Acid; D006801:Humans; D007668:Kidney; D007930:Leucine; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D016133:Polymerase Chain Reaction; D011509:Proteoglycans / Q000737:chemistry* / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D014162:Transfection
C546878:DCN protein, human; D018076:DNA, Complementary; C546879:Dcn protein, mouse; D058575:Decorin; D016326:Extracellular Matrix Proteins; D011509:Proteoglycans; D011994:Recombinant Proteins; D018698:Glutamic Acid; D003094:Collagen; D007930:Leucine