Structure formation in the C terminus of type III collagen guides disulfide cross-linking.
In type III collagen the main triple-helical domain is followed by a disulfide knot and the C-terminal propeptide, which are both essential for nucleation, stabilization and registration of the triple helix. We demonstrate that oxidative inter-chain disulfide bridging does not occur between the knot sequences GlyProCysCysGly of dissociated randomly coiled chains. N-terminal fusion of the obligatory trimeric domain of mini-fibritin is able to direct this process efficiently, demonstrating a folded precursor mechanism in which the thiol groups have to be properly placed for the formation of native disulfide bonds. The natural C-propeptide domain may act in a similar way as the mini-fibritin domain. After disulfide linkage and triple-helix formation the catalyzing mini-fibritin domain was removed by thrombin cleavage. In this way a short but stable triple-helical collagen fragment was expressed in Escherichia coli for structural and functional studies.
Boudko
Sergei P
SP
Biozentrum, University of Basel, Klingelbergstr 70, CH-4056 Basel, Switzerland.
Engel
Jürgen
J
D002152:Calorimetry, Differential Scanning; D002942:Circular Dichroism; D024061:Collagen Type III / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D003432:Cross-Linking Reagents; D004220:Disulfides / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism; D013058:Mass Spectrometry; D010084:Oxidation-Reduction; D010446:Peptide Fragments / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011487:Protein Conformation; D017510:Protein Folding; D011994:Recombinant Proteins / Q000378:metabolism; D014461:Ultracentrifugation; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism
D024061:Collagen Type III; D003432:Cross-Linking Reagents; D004220:Disulfides; D010446:Peptide Fragments; D011994:Recombinant Proteins; D014764:Viral Proteins; C057839:fibritin protein, Enterobacteria phage T4