Molecular basis of the regulation of Beclin 1-dependent autophagy by the γ-herpesvirus 68 Bcl-2 homolog M11

Sangita Sinha, Christopher L. Colbert, Nils Becker, Yongjie Wei, Beth Levine

Research output: Contribution to journalArticle

127 Scopus citations

Abstract

γ-Herpesviruses (γHVs), including important human pathogens such as Epstein Barr virus, Kaposi's sarcoma-associated HV, and the murine γHV68, encode homologs of the antiapoptotic, cellular Bcl-2 (cBcl-2) to promote viral replication and pathogenesis. The precise molecular details by which these proteins function in viral infection are poorly understood. Autophagy, a lysosomal degradation pathway, is inhibited by the interaction of cBcl-2s with a key autophagy effector, Beclin 1, and can also be inhibited by γHV Bcl-2s. Here we investigate the γHV68 M11-Beclin 1 interaction in atomic detail, using biochemical and structural approaches. We show that the Beclin 1 BH3 domain is the primary determinant of binding to M11 and other Bcl-2s, and this domain binds in a hydrophobic groove on M11, reminiscent of the binding of different BH3 domains to other Bcl-2s. Unexpectedly, regions outside of, but contiguous with, the Beclin 1 BH3 domain also contribute to this interaction. We find that M11 binds to Beclin 1 more strongly than do KSHV Bcl-2 or cBcl-2. Further, the differential affinity of M11 for different BH3 domains is caused by subtle, yet significant, variations in the atomic details of each interaction. Consistent with our structural analysis, we find that Beclin 1 residues L116 and F123, and M11 residue pairs G86 + R87 and Y60 + L74, are required for M11 to bind to Beclin 1 and downregulate autophagy. Thus, our results suggest that M11 inhibits autophagy through a mechanism that involves the binding of the Beclin 1 BH3 domain in the M11 hydrophobic surface groove.

Original languageEnglish (US)
Pages (from-to)989-997
Number of pages9
JournalAutophagy
Volume4
Issue number8
DOIs
StatePublished - Nov 16 2008

Keywords

  • Apoptosis
  • Autophagy
  • Bcl-2
  • Beclin 1
  • Viral Bcl-2
  • γ-herpesvirus

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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