Targeting γ-herpesvirus 68 Bcl-2-mediated down-regulation of autophagy

J Biol Chem. 2014 Mar 21;289(12):8029-40. doi: 10.1074/jbc.M113.515361. Epub 2014 Jan 17.


γ-herpesviruses (γHVs) are common human pathogens that encode homologs of the anti-apoptotic cellular Bcl-2 proteins, which are critical to viral reactivation and oncogenic transformation. The murine γHV68 provides a tractable in vivo model for understanding general features of these important human pathogens. Bcl-XL, a cellular Bcl-2 homolog, and the murine γHV68 Bcl-2 homolog, M11, both bind to a BH3 domain within the key autophagy effector Beclin 1 with comparable affinities, resulting in the down-regulation of Beclin 1-mediated autophagy. Despite this similarity, differences in residues lining the binding site of M11 and Bcl-XL dictate varying affinities for the different BH3 domain-containing proteins. Here we delineate Beclin 1 differential specificity determinants for binding to M11 or Bcl-XL by quantifying autophagy levels in cells expressing different Beclin 1 mutants and either M11 or Bcl-XL, and we show that a G120E/D121A Beclin 1 mutant selectively prevents down-regulation of Beclin 1-mediated autophagy by Bcl-XL, but not by M11. We use isothermal titration calorimetry to identify a Beclin 1 BH3 domain-derived peptide that selectively binds to M11, but not to Bcl-XL. The x-ray crystal structure of this peptide bound to M11 reveals the mechanism by which the M11 BH3 domain-binding groove accommodates this M11-specific peptide. This information was used to develop a cell-permeable peptide inhibitor that selectively inhibits M11-mediated, but not Bcl-XL-mediated, down-regulation of autophagy.

Keywords: Autophagy; Bcl-2 Family Proteins; Crystal Structure; Herpesvirus; Host Defense; Host-Pathogen Interactions; Protein-Protein Interactions.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Apoptosis Regulatory Proteins / chemistry
  • Apoptosis Regulatory Proteins / metabolism
  • Autophagy / drug effects*
  • Beclin-1
  • Cell Line, Tumor
  • Crystallography, X-Ray
  • Down-Regulation / drug effects*
  • Gammaherpesvirinae / chemistry
  • Gammaherpesvirinae / physiology*
  • Herpesviridae Infections / drug therapy
  • Herpesviridae Infections / metabolism
  • Host-Pathogen Interactions / drug effects*
  • Humans
  • Membrane Proteins / chemistry
  • Membrane Proteins / metabolism
  • Mice
  • Models, Molecular
  • Molecular Sequence Data
  • Peptides / chemistry
  • Peptides / pharmacology*
  • Protein Interaction Maps
  • Proto-Oncogene Proteins c-bcl-2 / chemistry
  • Proto-Oncogene Proteins c-bcl-2 / metabolism*
  • Sequence Alignment
  • Viral Proteins / chemistry
  • Viral Proteins / metabolism*
  • bcl-X Protein / chemistry
  • bcl-X Protein / metabolism


  • Apoptosis Regulatory Proteins
  • BECN1 protein, human
  • Beclin-1
  • Membrane Proteins
  • Peptides
  • Proto-Oncogene Proteins c-bcl-2
  • Viral Proteins
  • bcl-X Protein