COMP acts as a catalyst in collagen fibrillogenesis.
We have previously reported that COMP (cartilage oligomeric matrix protein) is prominent in cartilage but is also present in tendon and binds to collagens I and II with high affinity. Here we show that COMP influences the fibril formation of these collagens. Fibril formation in the presence of pentameric COMP was much faster, and the amount of collagen in fibrillar form was markedly increased. Monomeric COMP, lacking the N-terminal coiled-coil linker domain, decelerated fibrillogenesis. The data show that stimulation of collagen fibrillogenesis depends on the pentameric nature of COMP and not only on collagen binding. COMP interacts primarily with free collagen I and II molecules, bringing several molecules to close proximity, apparently promoting further assembly. These assemblies further join in discrete steps to a narrow distribution of completed fibril diameters of 149 +/- 16 nm with a banding pattern of 67 nm. COMP is not found associated with the mature fibril and dissociates from the collagen molecules or their early assemblies. However, a few COMP molecules are found bound to more loosely associated molecules at the tip/end of the growing fibril. Thus, COMP appears to catalyze the fibril formation by promoting early association of collagen molecules leading to increased rate of fibrillogenesis and more distinct organization of the fibrils.
Halász
Krisztina
K
Department of Experimental Medical Science, Lund University, SE-221 84 Lund, Sweden.
Kassner
Anja
A
Mörgelin
Matthias
M
Heinegård
Dick
D
D000143:Acids / Q000494:pharmacology; D000818:Animals; D015153:Blotting, Western; D002021:Buffers; D002384:Catalysis; D002417:Cattle; D003094:Collagen / Q000378:metabolism*; D024042:Collagen Type I / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism / Q000648:ultrastructure; D024043:Collagen Type II / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism / Q000648:ultrastructure; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D016326:Extracellular Matrix Proteins / Q000032:analysis / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D006023:Glycoproteins / Q000032:analysis / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D017979:Gold Colloid; D006531:HEPES / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D006909:Hydroxyproline / Q000032:analysis; D007150:Immunohistochemistry; D007700:Kinetics; D064235:Matrilin Proteins; D009391:Nephelometry and Turbidimetry; D010316:Particle Size; D010434:Pepsin A / Q000494:pharmacology; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012867:Skin / Q000737:chemistry; D020349:Surface Plasmon Resonance; D013696:Temperature; D013997:Time Factors
D000143:Acids; D002021:Buffers; D024042:Collagen Type I; D024043:Collagen Type II; D016326:Extracellular Matrix Proteins; D006023:Glycoproteins; D017979:Gold Colloid; D064235:Matrilin Proteins; D011994:Recombinant Proteins; D003094:Collagen; D010434:Pepsin A; D006909:Hydroxyproline; D006531:HEPES