Hypoxia-induced assembly of prolyl hydroxylase PHD3 into complexes: implications for its activity and susceptibility for degradation by the E3 ligase Siah2

Biochem J. 2007 Jan 1;401(1):217-26. doi: 10.1042/BJ20061135.


PHD1-3 (prolyl hydroxylases 1-3) catalyse the hydroxylation of HIF (hypoxia-inducible factor)-alpha subunit that triggers the substrate ubiquitination and subsequent degradation. The RING (really interesting new gene) finger E3 ligase Siah2 preferentially targets PHD3 for degradation. Here, we identify the requirements for such selective targeting. Firstly, PHD3 lacks an N-terminal extension found in PHD1 and PHD2; deletion of this domain from PHD1 and PHD2 renders them susceptible to degradation by Siah2. Secondly, PHD3 can homo- and hetero-multimerize with other PHDs. Consequently, PHD3 is found in high-molecular-mass fractions that were enriched in hypoxia. Interestingly, within the lower-molecular-mass complex, PHD3 exhibits higher specific activity towards hydroxylation of HIF-1alpha and co-localizes with Siah2, suggesting that Siah2 limits the availability of the more active form of PHD3. These findings provide new insight into the mechanism underlying the regulation of PHD3 availability and activity in hypoxia by the E3 ligase Siah2.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Hypoxia / physiology*
  • Cell Line
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Dioxygenases / genetics
  • Dioxygenases / metabolism*
  • Humans
  • Hydroxylation
  • Hypoxia-Inducible Factor-Proline Dioxygenases
  • Kidney
  • Kinetics
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Plasmids
  • Polycomb-Group Proteins
  • Procollagen-Proline Dioxygenase / genetics
  • Procollagen-Proline Dioxygenase / metabolism
  • Recombinant Proteins / metabolism
  • Sequence Deletion
  • Transcription Factors / genetics
  • Transcription Factors / metabolism
  • Transfection
  • Ubiquitin-Protein Ligases / genetics
  • Ubiquitin-Protein Ligases / metabolism*


  • DNA-Binding Proteins
  • Nuclear Proteins
  • PHF1 protein, human
  • Polycomb-Group Proteins
  • Recombinant Proteins
  • Transcription Factors
  • Dioxygenases
  • EGLN1 protein, human
  • Procollagen-Proline Dioxygenase
  • EGLN3 protein, human
  • Hypoxia-Inducible Factor-Proline Dioxygenases
  • Ubiquitin-Protein Ligases
  • seven in absentia proteins