Collagen fibrillogenesis during sea urchin development--retention of SURF motifs from the N-propeptide of the 2alpha chain in mature fibrils.
The sea urchin 2alpha fibrillar collagen chain has a unique amino-propeptide structure with several repetitions of a still unknown 140-145-amino-acid, four-Cys module called SURF (for sea urchin fibrillar module). To follow the expression of the amino-propeptide of the 2alpha chain and assign a function to this domain, we have overproduced in Escherichia coli several recombinant proteins corresponding either to the amino-propeptide or to the amino-telopeptide. Monoclonal and/or polyclonal antibodies against these recombinant proteins allowed us to observe a similar tissue distribution during the first stages of development. A signal is first observed at the prism stage as intracellular spots in mesenchymal cells. In plutei, immunofluorescence staining is observed around the skeleton spicules and as a thin meshwork surrounding the mesenchymal cells. At the ultrastructural level, and using antibodies against the amino-propeptide, gold particles are observed at the surface of 25 nm thin periodic fibrils. By rotary shadowing, these fibrils show a brush-bottle aspect, exhibiting at their surface numerous periodically distributed thin rods ended by a small globule. These data indicate that the amino-propeptide is maintained during fibrillogenesis. As previously suggested, the retention of the amino-propeptide could play an important role in regulation of the fibril growth. We propose that the important region of this amino-propeptide in the widely encountered 25-nm-diameter fibrils is the short triple-helical segment. The globular part of the amino-propeptide will not only restrict the fibril growth but also interact with other neighbouring components and playing, as suspected from our immunofluorescence studies, a function during the spiculogenesis of the sea urchin embryo.
Lethias
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Institut de Biologie et Chimie des Protéines, CNRS UPR 412, Uiversité Claude Bernard, Lyon, France.
Exposito
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Garrone
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D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000276:immunology; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D003094:Collagen / Q000096:biosynthesis* / Q000737:chemistry* / Q000276:immunology; D024042:Collagen Type I; D004926:Escherichia coli; D051379:Mice; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D010455:Peptides / Q000276:immunology; D010748:Phosphopeptides / Q000737:chemistry* / Q000276:immunology; D011347:Procollagen; D011348:Procollagen N-Endopeptidase / Q000378:metabolism; D011498:Protein Precursors / Q000737:chemistry*; D011994:Recombinant Proteins / Q000276:immunology; D012617:Sea Urchins
D000906:Antibodies; D024042:Collagen Type I; C062121:N-propeptide type I collagen; D010455:Peptides; D010748:Phosphopeptides; D011347:Procollagen; D011498:Protein Precursors; D011994:Recombinant Proteins; C052929:collagen type I trimeric cross-linked peptide; D003094:Collagen; D011348:Procollagen N-Endopeptidase