Insights into how CUB domains can exert specific functions while sharing a common fold: conserved and specific features of the CUB1 domain contribute to the molecular basis of procollagen C-proteinase enhancer-1 activity

J Biol Chem. 2007 Jun 8;282(23):16924-33. doi: 10.1074/jbc.M701610200. Epub 2007 Apr 19.


Procollagen C-proteinase enhancers (PCPE-1 and -2) are extracellular glycoproteins that can stimulate the C-terminal processing of fibrillar procollagens by tolloid proteinases such as bone morphogenetic protein-1. They consist of two CUB domains (CUB1 and -2) that alone account for PCPE-enhancing activity and one C-terminal NTR domain. CUB domains are found in several extracellular and plasma membrane-associated proteins, many of which are proteases. We have modeled the structure of the CUB1 domain of PCPE-1 based on known three-dimensional structures of CUB-containing proteins. Sequence alignment shows conserved amino acids, notably two acidic residues (Asp-68 and Asp-109) involved in a putative surface-located calcium binding site, as well as a conserved tyrosine residue (Tyr-67). In addition, three residues (Glu-26, Thr-89, and Phe-90) are found only in PCPE CUB1 domains, in putative surface-exposed loops. Among the conserved residues, it was found that mutations of Asp-68 and Asp-109 to alanine almost completely abolished PCPE-1 stimulating activity, whereas mutation of Tyr-67 led to a smaller reduction of activity. Among residues specific to PCPEs, mutation of Glu-26 and Thr-89 had little effect, whereas mutation of Phe-90 dramatically decreased the activity. Changes in activity were paralleled by changes in binding of different PCPE-1 mutants to a mini-procollagen III substrate, as shown by surface plasmon resonance. We conclude that PCPE-stimulating activity requires a calcium binding motif in the CUB1 domain that is highly conserved among CUB-containing proteins but also that PCPEs contain specific sites that could become targets for the development of novel anti-fibrotic therapies.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Bone Morphogenetic Protein 1
  • Bone Morphogenetic Proteins / chemistry
  • Bone Morphogenetic Proteins / genetics*
  • Bone Morphogenetic Proteins / metabolism
  • Circular Dichroism
  • Conserved Sequence
  • DNA Primers
  • Enhancer Elements, Genetic*
  • Fluorescence
  • Humans
  • Metalloendopeptidases / chemistry
  • Metalloendopeptidases / genetics*
  • Metalloendopeptidases / metabolism
  • Models, Molecular
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Protein Binding
  • Protein Folding
  • Sequence Homology, Amino Acid
  • Surface Plasmon Resonance


  • Bone Morphogenetic Proteins
  • DNA Primers
  • Metalloendopeptidases
  • BMP1 protein, human
  • Bone Morphogenetic Protein 1