Structural and functional characterization of recombinant matrilin-3 A-domain and implications for human genetic bone diseases.
Mutations in matrilin-3 result in multiple epiphyseal dysplasia, which is characterized by delayed and irregular bone growth and early onset osteoarthritis. The majority of disease-causing mutations are located within the beta-sheet of the single A-domain of matrilin-3, suggesting that they disrupt the structure and/or function of this important domain. Indeed, the expression of mutant matrilin-3 results in its intracellular retention within the rough endoplasmic reticulum of cells, where it elicits an unfolded protein response. To understand the folding characteristics of the matrilin-3 A-domain we determined its structure using CD, analytical ultracentrifugation, and dual polarization interferometry. This study defined novel structural features of the matrilin-3 A-domain and identified a conformational change induced by the presence or the absence of Zn(2+). In the presence of Zn(2+) the A-domain adopts a more stable "tighter" conformation. However, after the removal of Zn(2+) a potential structural rearrangement of the metal ion-dependent adhesion site motif occurs, which leads to a more "relaxed" conformation. Finally, to characterize the interactions of the matrilin-3 A-domain we performed binding studies on a BIAcore using type II and IX collagen and cartilage oligomeric matrix protein. We were able to demonstrate that it binds to type II and IX collagen and cartilage oligomeric matrix protein in a Zn(2+)-dependent manner. Furthermore, we have also determined that the matrilin-3 A-domain appears to bind exclusively to the COL3 domain of type IX collagen and that this binding is abolished in the presence of a disease causing mutation in type IX collagen.
Fresquet
Maryline
M
Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, United Kingdom.
Jowitt
Thomas A
TA
Ylöstalo
Joni
J
Coffey
Paul
P
Meadows
Roger S
RS
Ala-Kokko
Leena
L
Thornton
David J
DJ
Briggs
Michael D
MD
D001847:Bone Diseases / Q000235:genetics* / Q000378:metabolism*; D002356:Cartilage / Q000378:metabolism; D002942:Circular Dichroism; D024081:Collagen Type IX / Q000737:chemistry; D018870:Endoplasmic Reticulum, Rough / Q000378:metabolism; D016326:Extracellular Matrix Proteins / Q000737:chemistry*; D006801:Humans; D064235:Matrilin Proteins; D008854:Microscopy, Electron; D008968:Molecular Conformation; D009154:Mutation; D011487:Protein Conformation; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry*; D020349:Surface Plasmon Resonance; D015032:Zinc / Q000737:chemistry
D024081:Collagen Type IX; D016326:Extracellular Matrix Proteins; D064235:Matrilin Proteins; D011994:Recombinant Proteins; D015032:Zinc