Distinct Maturations of N-propeptide Domains in Fibrillar Procollagen Molecules Involved in the Formation of Heterotypic Fibrils in Adult Sea Urchin Collagenous Tissues

• Published in: The Journal of biological chemistry 2004-03, Vol.279 (11), p.9811-9817
• Main Authors: Cluzel, Caroline, Lethias, Claire, Garrone, Robert, Exposito, Jean-Yves
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Blotting, Western; Collagen - chemistry; DNA - chemistry; DNA, Complementary - metabolism; Echinoidea; Extracellular Matrix Proteins - chemistry; Isoelectric Focusing; Marine; Microscopy, Electron; Microscopy, Fluorescence; Models, Genetic; Molecular Sequence Data; Pepsin A - chemistry; Peptides - chemistry; Procollagen - chemistry; Protein Structure, Tertiary; Reverse Transcriptase Polymerase Chain Reaction; Sea Urchins - chemistry; Sequence Homology, Amino Acid; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M311803200

We have characterized the primary structure of a new sea urchin fibrillar collagen, the 5α chain, including nine repeats of the sea urchin fibrillar module in its N-propeptide. By Western blot and immunofluorescence analyses, we have shown that 5α is co-localized in adult collagenous ligaments with the 2α fibrillar collagen chain and fibrosurfin, two other extracellular matrix proteins possessing sea urchin fibrillar modules. At the ultrastructural level, the 5α N-propeptide is detected at the surface of fibrils, suggesting the retention of this domain in mature collagen molecules. Biochemical characterization of pepsinized collagen molecules extracted from the test tissue (the endoskeleton) together with a matrix-assisted laser desorption ionization time-of-flight analysis allowed us to determine that 5α is a quantitatively minor fibrillar collagen chain in comparison with the 1α and 2α chains. Moreover, 5α forms heterotrimeric molecules with two 1α chains. Hence, as in vertebrates, sea urchin collagen fibrils are made up of quantitatively major and minor fibrillar molecules undergoing distinct maturation of their N-propeptide regions and participating in the formation of heterotypic fibrils.