Structure and functional analysys of the cell death promoting protein cardiolipin-associated bax

Juanita C. Sharpe, Ph.D.

Department of Biological Sciences

Cancer arises as a result of the inability of damaged cells to initiate a signaling cascade that results in the destruction of the cell and clearance from the body.  This process, known as apoptosis, is necessary to prevent reproduction of damaged cells that leads to cancer.  A family of proteins known as the Bcl-2 protein family regulates apoptosis.  The Bcl-2 protein family works to promote cell death through the interaction of death promoting proteins.  Bax, a pro-apoptotic member of this family, initiates the cell death cascade by releasing cytochrome C.  Bax has the ability to mediate cytochrome c release by working in conjunction with cardiolipin.  Previous studies have shown that the presence of cardiolipin enhances the ability of Bax to form pores in reconstituted membranes through an, as yet, unknown mechanism.  Preliminary data from our lab has begun to elucidate the mechanism of interaction between Bax and cardiolipin.  In the presence of cardiolipin Bax undergoes a unique conformational change that facilitates the release of molecules from model membranes.  The goals of the current project are to determine the impact that this conformational change has on the active and functional conformation of Bax.  Our goals are to detail the structural changes and to correlate these changes with the function of Bax at the membrane.  This will be achieved by studying pore formation and oligomerization of membrane-associated Bax using fluorescent spectroscopic techniques.  We will also study how regions of Bax contributes to membrane recognition, pore formation and oligomerization through the use of mutants.  The two regions of Bax that are of interest are the BH3 domain, also called the putative cardiolipin binding region, and the c-terminal hydrophobic domain.  Understanding the mechanisms of pore formation and oligomerization as well as how domains of Bax contribute to the membrane-active conformation will enhance our understanding of apoptosis and aid in our ability to overcome the barriers that cancer cells erect to evade apoptosis.

Selected Publications

Arnoult D., Bartle LM, Skaletskaya A, Poncet D, Naoulfal Z, Park PU, Sharpe Juanita, Richard J. Youle and Victor S. Goldmacher. Cytomegalovirus cell death supressor vMIA blocks Bax- but not Bak-mediated apoptosis by binding and sequestering Bax at mitochondria.  PNAS (2004) 101:21  7988-7993.

Sharpe JC,Arnoult D, and Youle RJ. Control of mitochondrial permeability by Bcl-2 family members.   BBA (2004) 1644107-113.

Arnoult D, Gaume B, Karobowski M, Sharpe JC, Cecconi F, and Youle RJ. Mitochondrial release of AIF and Endog requires caspase activation downstream of Bax/Bak-mediated permeabilization.  EMBO J.,  2003 22:4385-99.

Cecelia M.P. Rodrigues, Susana Sola, Jose J.G. Moura, Juanita C. Sharpe, and Clifford J. Steer.  Tauroursodeoxycholic Acid Prevents Bax-induced Membrane Perturbation and Cytochrome c Release in Isolated Mitochondria.   Biochemistry, 2003  42 (10):3070-80.

Gorka Basanez, Juanita C. Sharpe, J. Galanis, Teresa B. Brandt, J.M. Hardwick, and J. Zimmerberg. Bax type apoptotic proteins porate pure lipid bilayers trhougha mechanism sensitive to intrinsic monolayer curvature.   J. Biol. Chem., 2002  277(51 ):49360-5.

J.C. Sharpe and E. London Diphtheria Toxin Forms Pores of Different Sizes Depending on Its Concentration in Membranes: Probable Relationship to Oligomerization. Journal of Membrane Biology (1999)171, 209-221.

Recent Student Presentations

Edgar L Glover, Byeong-Gyu Park and Juanita C. Sharpe, THE MUTAGENESIS AND PURIFICATION OF RECOMBINANT BAX BH3 REGION MUTANTS,  10th Annual Illinois Louis Stokes Alliance For Minority Participation (Ls-Amp) Student Research Symposium, Glenview, Illinois, October 12-13, 2007.

Agnes K. Kisai, Nkechiyere Vidal Nwani and Juanita C. Sharpe, OPTIMIZATION OF RECOMBINANT BAX EXPRESSION,  10th Annual Illinois Louis Stokes Alliance For Minority Participation (Ls-Amp) Student Research Symposium, Glenview, Illinois, October 12-13, 2007.

Michonne C. Berry and Juanita C. Sharpe, Recombinant Bax Preferentially Binds to SUV Containing Cardiolipin Resulting in a Conformational Change, 9th Annual Illinois LS-AMP Student Research Conference, Glenview, Illinois, October 607, 2006.

Edgar Glover and Juanita C. Sharpe,  Mutagenesis of Bax Causes Reduction in Cardiolipin Binding, 9th Annual Illinois LS-AMP Student Research Conference, Glenview, Illinois, October 607, 2006.

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This page was last updated on 01/12/09

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