The NC2 Domain of Collagen IX Provides Chain Selection and Heterotrimerization

• Published in: The Journal of biological chemistry Vol. 285; no. 31; pp. 23721 - 23731
• Main Authors: Boudko, Sergei P., Zientek, Keith D., Vance, Jesse, Hacker, Jessica L., Engel, Jürgen, Bächinger, Hans Peter
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 30.07.2010; American Society for Biochemistry and Molecular Biology
• Subjects: Amino Acid Sequence; C-Peptide - chemistry; Circular Dichroism; Cloning, Molecular; Collagen; Collagen IX; Collagen Type IX - chemistry; Dimerization; Extracellular Matrix Proteins; FACITs; Glycobiology and Extracellular Matrices; Heterotrimerization Domain; Humans; Molecular Sequence Data; NC2 Domain; Oxygen - chemistry; Protein Binding; Protein Domains; Protein Folding; Protein Self-assembly; Protein Structure and Folding; Protein Structure, Tertiary; Recombinant Proteins - chemistry; Sequence Homology, Amino Acid; Thermodynamics; Thrombin - chemistry; Protein Self-assembly; NC2 Domain; Heterotrimerization Domain; Extracellular Matrix Proteins; Collagen IX; Collagen; FACITs; Protein Domains; Protein Folding
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M110.128405

The mechanism of chain selection and trimerization of fibril-associated collagens with interrupted triple helices (FACITs) differs from that of fibrillar collagens that have special C-propeptides. We recently showed that the second carboxyl-terminal non-collagenous domain (NC2) of homotrimeric collagen XIX forms a stable trimer and substantially stabilizes a collagen triple helix attached to either end. We then hypothesized a general trimerizing role for the NC2 domain in other FACITs. Here we analyzed the NC2 domain of human heterotrimeric collagen IX, the only member of FACITs with all three chains encoded by distinct genes. Upon oxidative folding of equimolar amounts of the α1, α2, and α3 chains of NC2, a stable heterotrimer with a disulfide bridge between α1 and α3 chains is formed. Our experiments show that this heterotrimerization domain can stabilize a short triple helix attached at the carboxyl-terminal end and allows for the proper oxidation of the cystine knot of type III collagen after the short triple helix.