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Bax forms an oligomer via separate, yet interdependent, surfaces

Zhi Zhang1, Weijia Zhu, Suzanne M Lapolla

  • 1Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73126, USA.

The Journal of Biological Chemistry
|April 13, 2010
PubMed

Insights

Bax protein oligomerization, crucial for apoptosis, involves two distinct interaction surfaces. These surfaces, the BH1-3 groove and a rear pocket, allosterically couple to drive membrane permeabilization.

Area of Science:

  • Molecular Biology
  • Biochemistry
  • Cell Biology

Background:

  • Bcl-2 family proteins regulate mitochondrial outer membrane permeability and apoptosis.
  • Bax protein oligomerization is a key event in initiating membrane permeabilization.

Purpose of the Study:

  • To map the interaction interfaces of the Bax oligomer.
  • To elucidate the mechanism of Bax oligomerization.

Main Methods:

  • Site-specific photocross-linking using photo-reactive probes.
  • Utilizing Triton X-100 as a membrane surrogate.
  • Cross-linking experiments with Bax BH3 peptides and mutants.

Main Results:

  • Two distinct interaction surfaces on the Bax oligomer were identified: the BH1-3 groove and a rear pocket.
  • These surfaces interact with counterparts on neighboring proteins, forming two separate interfaces.
  • Interaction at the BH1-3 groove primes the rear pocket for subsequent interactions.

Conclusions:

  • Bax oligomerization is a multi-step process driven by interactions at distinct, allosterically coupled interfaces.
  • This mechanism ensures controlled permeabilization of the mitochondrial outer membrane.
  • Understanding Bax oligomerization provides insights into apoptotic pathways.

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