Dept. of Biochemistry and Molecular Biology
Oregon Health & Science University
Collagen is one of the most abundant proteins in the human body and plays an important role in the structural stability of many tissues. Collagen-associated proteins are essential for the correct biosynthesis of collagen. Defects in either collagen or collagenassociated proteins result in a myriad of diseases, underscoring the importance of both classes of molecules. Although much work has been performed on the triple helical domains found in all collagens, less is known about their non-collagenous domains. Here we report the crystal structure and biochemical characterization of the non-collagenous domain responsible for the trimerization of human type XV collagen. The structure is stabilized by the presence of hydrophobic cores in the individual monomeric chain as well as in the trimer assembly. The trimer is also exceptionally stable and forms at picomolar concentrations. Many non-collagenous proteins are associated with collagens, including a variety of enzymes and chaperones. We present data demonstrating that the resident endoplasmic reticulum protein complex consisting of prolyl 3-hydroxylase 1 (P3H1), cartilage associated protein (CRTAP) and cyclophilin B (CypB) performs three functions: the complex is a prolyl 3-hydroxylase, a molecular chaperone and a protein disulfide isomerase. To perform these functions, the complex is capable of binding both denatured and triple helical collagen. Attempts to overexpress P3H1 or CRTAP for further studies were unproductive as the proteins were either insoluble or not in biologically relevant conformations. The P3H1âCRTAPâCypB complex is purified out of chick embryos, and experiments were performed to enhance protein yield. Although some progress was made, the overall stability of the complex remains low, confounding attempts to perform more detailed structural analysis.
School of Medicine
Wirz, Jacqueline Alani, "Collagen and collagen-associated proteins studies on the type XV trimerization domain, prolyl 3-hydrolase and the prolyl 3-hydroxylase cartilage associated protein cyclophilin B complex" (2010). Scholar Archive. 462.