The X-ray structure of a BAK homodimer reveals an inhibitory zinc binding site

Tudor Moldoveanu; Qian Liu; Ante Tocilj; Mark Watson; Gordon Shore; Kalle Gehring

doi:10.1016/j.molcel.2006.10.014

The X-ray structure of a BAK homodimer reveals an inhibitory zinc binding site

Mol Cell. 2006 Dec 8;24(5):677-688. doi: 10.1016/j.molcel.2006.10.014.

Authors

Tudor Moldoveanu¹, Qian Liu², Ante Tocilj², Mark Watson³, Gordon Shore⁴, Kalle Gehring⁵

Affiliations

¹ Department of Biochemistry, McGill University, 3655 Promenade Sir William Osler, Montreal, QC, Canada H3G 1Y6. Electronic address: tudor.moldoveanu@stjude.org.
² Department of Biochemistry, McGill University, 3655 Promenade Sir William Osler, Montreal, QC, Canada H3G 1Y6.
³ GeminX Biotechnologies, Inc., Place du Parc, Montreal, QC, Canada H2X 4A5.
⁴ Department of Biochemistry, McGill University, 3655 Promenade Sir William Osler, Montreal, QC, Canada H3G 1Y6; GeminX Biotechnologies, Inc., Place du Parc, Montreal, QC, Canada H2X 4A5.
⁵ Department of Biochemistry, McGill University, 3655 Promenade Sir William Osler, Montreal, QC, Canada H3G 1Y6. Electronic address: kalle.gehring@mcgill.ca.

PMID: 17157251
DOI: 10.1016/j.molcel.2006.10.014

Abstract

BAK/BAX-mediated mitochondrial outer-membrane permeabilization (MOMP) drives cell death during development and tissue homeostasis from zebrafish to humans. In most cancers, this pathway is inhibited by BCL-2 family antiapoptotic members, which bind and block the action of proapoptotic BCL proteins. We report the 1.5 A crystal structure of calpain-proteolysed BAK, cBAK, to reveal a zinc binding site that regulates its activity via homodimerization. cBAK contains an occluded BH3 peptide binding pocket that binds a BID BH3 peptide only weakly . Nonetheless, cBAK requires activation by truncated BID to induce cytochrome c release in mitochondria isolated from bak/bax double-knockout mouse embryonic fibroblasts. The BAK-mediated MOMP is inhibited by low micromolar zinc levels. This inhibition is alleviated by mutation of the zinc-coordination site in BAK. Our results link directly the antiapoptotic effects of zinc to BAK.

Publication types

Comparative Study
Research Support, Non-U.S. Gov't

MeSH terms

Amino Acid Sequence
Animals
Apoptosis / drug effects
Binding Sites
Calpain / metabolism
Chlorides / pharmacology*
Crystallography, X-Ray
Humans
KB Cells
Magnetic Resonance Spectroscopy
Mice
Models, Molecular
Molecular Sequence Data
Peptide Fragments / metabolism
Protein Conformation
Protein Structure, Secondary
Proto-Oncogene Proteins / metabolism
Recombinant Proteins / antagonists & inhibitors
Recombinant Proteins / chemistry
Recombinant Proteins / genetics
Sensitivity and Specificity
Zinc Compounds / pharmacology*
bcl-2 Homologous Antagonist-Killer Protein / antagonists & inhibitors*
bcl-2 Homologous Antagonist-Killer Protein / chemistry*
bcl-2 Homologous Antagonist-Killer Protein / genetics

Substances

BAK1 protein, human
Bax protein (53-86)
Chlorides
Peptide Fragments
Proto-Oncogene Proteins
Recombinant Proteins
Zinc Compounds
bcl-2 Homologous Antagonist-Killer Protein
zinc chloride
Calpain