Characterization of novel cathepsin K mutations in the pro and mature polypeptide regions causing pycnodysostosis. Academic Article uri icon

Overview

abstract

  • Cathepsin K, a lysosomal cysteine protease critical for bone remodeling by osteoclasts, was recently identified as the deficient enzyme causing pycnodysostosis, an autosomal recessive osteosclerotic skeletal dysplasia. To investigate the nature of molecular lesions causing this disease, mutations in the cathepsin K gene from eight families were determined, identifying seven novel mutations (K52X, G79E, Q190X, Y212C, A277E, A277V, and R312G). Expression of the first pro region missense mutation in a cysteine protease, G79E, in Pichia pastoris resulted in an unstable precursor protein, consistent with misfolding of the proenzyme. Expression of five mature region missense defects revealed that G146R, A277E, A277V, and R312G precursors were unstable, and no mature proteins or protease activity were detected. The Y212C precursor was activated to its mature form in a manner similar to that of the wild-type cathepsin K. The mature Y212C enzyme retained its dipeptide substrate specificity and gelatinolytic activity, but it had markedly decreased activity toward type I collagen and a cathepsin K-specific tripeptide substrate, indicating that it was unable to bind collagen triple helix. These studies demonstrated the molecular heterogeneity of mutations causing pycnodysostosis, indicated that pro region conformation directs proper folding of the proenzyme, and suggested that the cathepsin K active site contains a critical collagen-binding domain.

publication date

  • March 1, 1999

Research

keywords

  • Cathepsins
  • Dysostoses
  • Mutation

Identity

PubMed Central ID

  • PMC408114

Scopus Document Identifier

  • 0345580617

Digital Object Identifier (DOI)

  • 10.1172/JCI653

PubMed ID

  • 10074491

Additional Document Info

volume

  • 103

issue

  • 5