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DNA-repair protein hHR23a alters its protein structure upon binding proteasomal subunit S5a.

The Rad23 family of proteins, including the human homologs hHR23a and hHR23b, stimulates nucleotide excision repair and has been shown to provide a novel link between proteasome-mediated protein degradation and DNA repair. In this work, we illustrate how the proteasomal subunit S5a regulates hHR23a protein structure. By using NMR spectroscopy, we have elucidated the structure and dynamic properties of the 40-kDa hHR23a protein and show it to contain four structured domains connected by flexible linker regions. In addition, we reveal that these domains interact in an intramolecular fashion, and by using residual dipolar coupling data in combination with chemical shift perturbation analysis, we present the hHR23a structure. By itself, hHR23a adopts a closed conformation defined by the interaction of an N-terminal ubiquitin-like domain with two ubiquitin-associated domains. Interestingly, binding of the proteasomal subunit S5a disrupts the hHR23a interdomain interactions and thereby causes it to adopt an opened conformation.

Pubmed ID: 14557549


  • Walters KJ
  • Lech PJ
  • Goh AM
  • Wang Q
  • Howley PM


Proceedings of the National Academy of Sciences of the United States of America

Publication Data

October 28, 2003

Associated Grants

  • Agency: NCI NIH HHS, Id: CA 097004-01A1
  • Agency: NCI NIH HHS, Id: CA 64888

Mesh Terms

  • Amino Acid Sequence
  • Binding Sites
  • Carrier Proteins
  • Cysteine Endopeptidases
  • DNA Repair
  • DNA Repair Enzymes
  • DNA-Binding Proteins
  • Humans
  • Magnetic Resonance Spectroscopy
  • Models, Molecular
  • Molecular Sequence Data
  • Multienzyme Complexes
  • Proteasome Endopeptidase Complex
  • Protein Binding
  • Protein Conformation
  • Protein Structure, Secondary
  • Protein Subunits