Unique structural features of a BCL-2 family protein CED-9 and biophysical characterization of CED-9/EGL-1 interactions

Cell Death Differ. 2003 Dec;10(12):1310-9. doi: 10.1038/sj.cdd.4401303.


The interactions between B-cell lymphoma 2 (BCL-2) family members are known to be mediated through the binding of the BH3 domain of a proapoptotic member to the BH3-binding groove of an antiapoptotic member. We determined the crystal structure of antiapoptotic CED-9, which reveals a unique C-terminal helix altering the common BH3-binding region. A coexpression system to produce CED-9 in complex with proapoptotic EGL-1 enabled us to show that the binding of EGL-1 to CED-9 is extremely stable, raising the melting temperature (T(M)) of CED-9 by 25 degrees C, and that the binding surface of CED-9 extends beyond the BH3-binding region and reaches the BH4 domain. Consistently, the T(M) and a 1H-15N correlation NMR spectrum of CED-9 in complex with EGL-1 are drastically different from those of CED-9 in complex with the EGL-1 BH3 peptide. The data suggest that the recognition between other BCL-2 family members may also involve much wider protein surfaces than is previously thought.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis
  • Apoptosis Regulatory Proteins
  • Caenorhabditis elegans Proteins / chemistry*
  • Caenorhabditis elegans Proteins / metabolism*
  • Circular Dichroism
  • Crystallography, X-Ray
  • Escherichia coli / metabolism
  • Magnetic Resonance Spectroscopy
  • Models, Molecular
  • Peptides / chemistry
  • Plasmids / metabolism
  • Point Mutation
  • Protein Binding
  • Protein Structure, Secondary
  • Protein Structure, Tertiary
  • Proteins / chemistry
  • Proto-Oncogene Proteins / chemistry*
  • Proto-Oncogene Proteins / metabolism
  • Proto-Oncogene Proteins c-bcl-2 / metabolism*
  • Recombinant Proteins / chemistry
  • Repressor Proteins / chemistry
  • Repressor Proteins / metabolism*
  • Temperature


  • Apoptosis Regulatory Proteins
  • Caenorhabditis elegans Proteins
  • Ced-9 protein, C elegans
  • EGL-1 protein, C elegans
  • Peptides
  • Proteins
  • Proto-Oncogene Proteins
  • Proto-Oncogene Proteins c-bcl-2
  • Recombinant Proteins
  • Repressor Proteins