Direct in vitro and in vivo evidence for interaction between Hsp47 protein and collagen triple helix

J Biol Chem. 2012 Feb 24;287(9):6810-8. doi: 10.1074/jbc.M111.280248. Epub 2012 Jan 10.

Abstract

Hsp47 (heat shock protein 47), a collagen-specific molecular chaperone, is essential for the maturation of various types of procollagens. Previous studies have suggested that Hsp47 may preferentially recognize the triple-helix form of procollagen rather than unfolded procollagen chains in the endoplasmic reticulum. However, the underlying mechanism has remained unclear because of limitations in the available methods for detecting in vitro and in vivo interactions between Hsp47 and collagen. In this study, we established novel methods for this purpose by adopting a time-resolved FRET technique in vitro and a bimolecular fluorescence complementation technique in vivo. Using these methods, we provide direct evidence that Hsp47 binds to collagen triple helices but not to the monomer form in vitro. We also demonstrate that Hsp47 binds a collagen model peptide in the trimer conformation in vivo. Hsp47 did not bind collagen peptides that had been modified to block their ability to form triple helices in vivo. These results conclusively indicate that Hsp47 recognizes the triple-helix form of procollagen in vitro and in vivo.

MeSH terms

  • Animals
  • Biotinylation
  • Chickens
  • Endoplasmic Reticulum / metabolism
  • Fluorescence Resonance Energy Transfer
  • HSP47 Heat-Shock Proteins / chemistry*
  • HSP47 Heat-Shock Proteins / genetics
  • HSP47 Heat-Shock Proteins / metabolism
  • HeLa Cells
  • Humans
  • In Vitro Techniques
  • Models, Chemical*
  • Molecular Chaperones / chemistry*
  • Molecular Chaperones / genetics
  • Molecular Chaperones / metabolism
  • Procollagen / chemistry*
  • Procollagen / metabolism
  • Protein Binding
  • Protein Folding
  • Protein Structure, Secondary
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Temperature

Substances

  • HSP47 Heat-Shock Proteins
  • Molecular Chaperones
  • Procollagen
  • Recombinant Proteins
  • SERPINH1 protein, human