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Biochemical characterization of the prolyl 3-hydroxylase 1.cartilage-associated protein.cyclophilin B complex

Yoshihiro Ishikawa1, Jackie Wirz, Janice A Vranka

  • 1Department of Biochemistry and Molecular Biology, Oregon Health and Science University, and Research Department, Shriners Hospital for Children, Portland, OR 97239, USA.

The Journal of Biological Chemistry
|May 8, 2009
PubMed

Insights

The P3H1.CRTAP.CypB complex acts as a collagen chaperone, aiding procollagen biosynthesis and regulating collagen fibril formation. This protein complex also exhibits peptidyl-prolyl cis-trans isomerase activity.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Protein Chemistry

Background:

  • The prolyl 3-hydroxylase 1 (P3H1), cartilage-associated protein (CRTAP), and cyclophilin B (CypB) complex resides in the rough endoplasmic reticulum.
  • P3H1 hydroxylates proline residues in collagen alpha chains, while CypB isomerizes peptidyl-prolyl bonds, impacting collagen triple helix formation.

Purpose of the Study:

  • To investigate the chaperone activity of the P3H1.CRTAP.CypB complex.
  • To determine the complex's role in collagen biosynthesis and fibril formation.

Main Methods:

  • Isolation of the P3H1.CRTAP.CypB complex from chick embryos using gelatin-Sepharose chromatography.
  • Assays for chaperone activity, including inhibition of citrate synthase thermal aggregation and rhodanese refolding.
  • In vitro collagen fibril formation assays.

Main Results:

  • The P3H1.CRTAP.CypB complex demonstrated significant chaperone activity, surpassing that of protein-disulfide isomerase.
  • The complex inhibited thermal aggregation of citrate synthase and aided in rhodanese refolding.
  • The complex delayed in vitro fibril formation of type I collagen, indicating collagen chaperone function.

Conclusions:

  • The P3H1.CRTAP.CypB complex functions as a molecular chaperone with potent activity.
  • This complex plays a crucial role in collagen biosynthesis by modulating triple helix formation and fibril assembly.

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