1
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Ma Y, Du M, Yang F, Mai Z, Zhang C, Qu W, Wang B, Wang X, Chen T. Quantifying the inhibitory effect of Bcl-xl on the action of Mff using live-cell fluorescence imaging. FEBS Open Bio 2019; 9:2041-2051. [PMID: 31587505 PMCID: PMC6886297 DOI: 10.1002/2211-5463.12739] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 09/18/2019] [Accepted: 10/04/2019] [Indexed: 12/22/2022] Open
Abstract
Mitochondrial fission regulates mitochondrial function and morphology, and has been linked to apoptosis. The mitochondrial fission factor (Mff), a tail‐anchored membrane protein, induces excessive mitochondrial fission, contributing to mitochondrial dysfunction and apoptosis. Here, we evaluated the inhibitory effect of Bcl‐xl, an antiapoptotic protein, on the action of Mff by using live‐cell fluorescence imaging. Microscopic imaging analysis showed that overexpression of Mff induced mitochondrial fragmentation and apoptosis, which were reversed by coexpression of Bcl‐xl. Microscopic imaging and live‐cell fluorescence resonance energy transfer analysis demonstrated that Bcl‐xl reconstructs the Mff network from punctate distribution of higher‐order oligomers to filamentous distribution of lower‐order oligomers. Live‐cell fluorescence resonance energy transfer two‐hybrid assay showed that Bcl‐xl interacted with Mff to form heterogenous oligomers with 1 : 2 stoichiometry in cytoplasm and 1 : 1 stoichiometry on mitochondria, indicating that two Bcl‐xl molecules primarily interact with four Mff molecules in cytoplasm, but with two Mff molecules on mitochondria. Mitochondrial fission factor (Mff)‐mediated mitochondrial fission is positively correlated with the self‐oligomerization of Mff. Bcl‐xl directly interacts with Mff to prevent Mff‐mediated mitochondrial fission and apoptosis. Bcl‐xl interacts with Mff to form heterogenous hexamers with 1 : 2 stoichiometry in cytoplasm and heterogenous tetramers with 1 : 1 stoichiometry on the mitochondrial membrane, respectively.![]()
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Affiliation(s)
- Yunyun Ma
- MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou, China
| | - Mengyan Du
- MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou, China
| | - Fangfang Yang
- MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou, China
| | - Zihao Mai
- MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou, China
| | - Chenshuang Zhang
- MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou, China
| | - Wenfeng Qu
- MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou, China
| | - Bin Wang
- MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou, China
| | - Xiaoping Wang
- Department of Pain Management, The First Affiliated Hospital, Jinan University, Guangzhou, China
| | - Tongsheng Chen
- MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou, China
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2
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Pécot J, Maillet L, Le Pen J, Vuillier C, Trécesson SDC, Fétiveau A, Sarosiek KA, Bock FJ, Braun F, Letai A, Tait SWG, Gautier F, Juin PP. Tight Sequestration of BH3 Proteins by BCL-xL at Subcellular Membranes Contributes to Apoptotic Resistance. Cell Rep 2017; 17:3347-3358. [PMID: 28009301 DOI: 10.1016/j.celrep.2016.11.064] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 10/14/2016] [Accepted: 11/21/2016] [Indexed: 12/26/2022] Open
Abstract
Anti-apoptotic BCL-2 family members bind to BH3-only proteins and multidomain BAX/BAK to preserve mitochondrial integrity and maintain survival. Whereas inhibition of these interactions is the biological basis of BH3-mimetic anti-cancer therapy, the actual response of membrane-bound protein complexes to these compounds is currently ill-defined. Here, we find that treatment with BH3 mimetics targeting BCL-xL spares subsets of cells with the highest levels of this protein. In intact cells, sequestration of some pro-apoptotic activators (including PUMA and BIM) by full-length BCL-xL is much more resistant to derepression than previously described in cell-free systems. Alterations in the BCL-xL C-terminal anchor that impacts subcellular membrane-targeting and localization dynamics restore sensitivity. Thus, the membrane localization of BCL-xL enforces its control over cell survival and, importantly, limits the pro-apoptotic effects of BH3 mimetics by selectively influencing BCL-xL binding to key pro-apoptotic effectors.
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Affiliation(s)
- Jessie Pécot
- CRCNA, INSERM, CNRS, Université d'Angers, Université de Nantes, 44035 Nantes, France
| | - Laurent Maillet
- CRCNA, INSERM, CNRS, Université d'Angers, Université de Nantes, 44035 Nantes, France
| | - Janic Le Pen
- CRCNA, INSERM, CNRS, Université d'Angers, Université de Nantes, 44035 Nantes, France
| | - Céline Vuillier
- CRCNA, INSERM, CNRS, Université d'Angers, Université de Nantes, 44035 Nantes, France
| | | | - Aurélie Fétiveau
- CRCNA, INSERM, CNRS, Université d'Angers, Université de Nantes, 44035 Nantes, France
| | | | - Florian J Bock
- Cancer Research UK Beatson Institute, Institute of Cancer Sciences, University of Glasgow, Garscube Estate, Switchback Road, Glasgow G61 1BD, UK
| | - Frédérique Braun
- CRCNA, INSERM, CNRS, Université d'Angers, Université de Nantes, 44035 Nantes, France
| | - Anthony Letai
- Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA
| | - Stephen W G Tait
- Cancer Research UK Beatson Institute, Institute of Cancer Sciences, University of Glasgow, Garscube Estate, Switchback Road, Glasgow G61 1BD, UK
| | - Fabien Gautier
- CRCNA, INSERM, CNRS, Université d'Angers, Université de Nantes, 44035 Nantes, France; ICO René Gauducheau, 44805 Saint Herblain, France.
| | - Philippe P Juin
- CRCNA, INSERM, CNRS, Université d'Angers, Université de Nantes, 44035 Nantes, France; ICO René Gauducheau, 44805 Saint Herblain, France.
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3
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Bhat V, Olenick MB, Schuchardt BJ, Mikles DC, McDonald CB, Farooq A. Molecular determinants of the binding specificity of BH3 ligands to BclXL apoptotic repressor. Biopolymers 2016; 101:573-82. [PMID: 24114183 DOI: 10.1002/bip.22419] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Revised: 09/22/2013] [Accepted: 09/23/2013] [Indexed: 12/31/2022]
Abstract
B-cell lymphoma extra-large protein (BclXL) serves as an apoptotic repressor by virtue of its ability to recognize and bind to BH3 domains found within a diverse array of proapoptotic regulators. Herein, we investigate the molecular basis of the specificity of the binding of proapoptotic BH3 ligands to BclXL. Our data reveal that while the BH3 ligands harboring the LXXX[A/S]D and [R/Q]XLXXXGD motif bind to BclXL with high affinity in the submicromolar range, those with the LXXXGD motif afford weak interactions. This suggests that the presence of a glycine at the fourth position (G+4)--relative to the N-terminal leucine (L0) within the LXXXGD motif--mitigates binding, unless the LXXXGD motif also contains arginine/glutamine at the -2 position. Of particular note is the observation that the residues at the +4 and -2 positions within the LXXX[A/S]D and [R/Q]XLXXXGD motifs appear to be energetically coupled-replacement of either [A/S]+4 or [R/Q]-2 with other residues has little bearing on the binding affinity of BH3 ligands harboring one of these motifs. Collectively, our study lends new molecular insights into understanding the binding specificity of BH3 ligands to BclXL with important consequences on the design of novel anticancer drugs.
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Affiliation(s)
- Vikas Bhat
- Department of Biochemistry and Molecular Biology, Miller School of Medicine, University of Miami, Miami, FL, 33136
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4
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Yao Y, Fujimoto LM, Hirshman N, Bobkov AA, Antignani A, Youle RJ, Marassi FM. Conformation of BCL-XL upon Membrane Integration. J Mol Biol 2015; 427:2262-70. [PMID: 25731750 DOI: 10.1016/j.jmb.2015.02.019] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Revised: 02/11/2015] [Accepted: 02/15/2015] [Indexed: 10/23/2022]
Abstract
BCL-XL is an anti-apoptotic BCL-2 family protein found both in the cytosol and bound to intracellular membranes. Structural studies of BCL-XL have advanced by deleting its hydrophobic C-terminus and adding detergents to enhance solubility. However, since the C-terminus is essential for function and detergents strongly affect structure and activity, the molecular mechanisms controlling intracellular localization and cytoprotective activity are incompletely understood. Here we describe the conformations and ligand binding activities of water-soluble and membrane-bound BCL-XL, with its complete C-terminus, in detergent-free environments. We show that the C-terminus interacts with a conserved surface groove in the water-soluble state of the protein and inserts across the phospholipid bilayer in the membrane-bound state. Contrary to current models, membrane binding does not induce a conformational change in the soluble domain and both states bind a known ligand with affinities that are modulated by the specific state of the protein.
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Affiliation(s)
- Yong Yao
- Sanford-Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Lynn M Fujimoto
- Sanford-Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Nathan Hirshman
- Sanford-Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Andrey A Bobkov
- Sanford-Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Antonella Antignani
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Richard J Youle
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Francesca M Marassi
- Sanford-Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA.
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5
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Bhat V, Olenick MB, Schuchardt BJ, Mikles DC, McDonald CB, Farooq A. Biophysical basis of the promiscuous binding of B-cell lymphoma protein 2 apoptotic repressor to BH3 ligands. J Mol Recognit 2014; 26:501-13. [PMID: 23996493 DOI: 10.1002/jmr.2295] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Revised: 06/25/2013] [Accepted: 06/26/2013] [Indexed: 01/09/2023]
Abstract
B-cell lymphoma protein 2 (Bcl2) apoptotic repressor carries out its function by virtue of its ability to bind to BH3 domains of various pro-apoptotic regulators in a highly promiscuous manner. Herein, we investigate the biophysical basis of such promiscuity of Bcl2 toward its cognate BH3 ligands. Our data show that although the BH3 ligands harboring the LXXXAD motif bind to Bcl2 with submicromolar affinity, those with the LXXX[G/S]D motif afford weak interactions. This implies that the replacement of alanine at the fourth position (A + 4)-relative to the N-terminal leucine (L0) within the LXXXAD motif-to glycine/serine results in the loss of free energy of binding. Consistent with this notion, the A + 4 residue within the BH3 ligands harboring the LXXXAD motif engages in key intermolecular van der Waals contacts with A149 lining the ligand binding groove within Bcl2, whereas A + 4G/S substitution results in the disruption of such favorable binding interactions. Of particular interest is the observation that although increasing ionic strength has little or negligible effect on the binding of high-affinity BH3 ligands harboring the LXXXAD motif, the binding of those with the LXXX[G/S]D motif in general experiences a varying degree of enhancement. This salient observation is indicative of the fact that hydrophobic forces not only play a dominant but also a universal role in driving the Bcl2-BH3 interactions. Taken together, our study sheds light on the molecular basis of the factors governing the promiscuous binding of Bcl2 to pro-apoptotic regulators and thus bears important consequences on the development of rational therapeutic approaches.
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Affiliation(s)
- Vikas Bhat
- Department of Biochemistry & Molecular Biology, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
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6
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Maity A, Yadav S, Verma CS, Ghosh Dastidar S. Dynamics of Bcl-xL in water and membrane: molecular simulations. PLoS One 2013; 8:e76837. [PMID: 24116174 PMCID: PMC3792877 DOI: 10.1371/journal.pone.0076837] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 08/28/2013] [Indexed: 11/18/2022] Open
Abstract
The Bcl2 family of proteins is capable of switching the apoptotic machinery by directly controlling the release of apoptotic factors from the mitochondrial outer membrane. They have 'pro' and 'anti'-apoptotic subgroups of proteins which antagonize each other's function; however a detailed atomistic understanding of their mechanisms based on the dynamical events, particularly in the membrane, is lacking. Using molecular dynamics simulations totaling 1.6µs we outline the major differences between the conformational dynamics in water and in membrane. Using implicit models of solvent and membrane, the simulated results reveal a picture that is in agreement with the 'hit-and run' concept which states that BH3-only peptides displace the tail (which acts as a pseudo substrate of the protein itself) from its binding pocket; this helps the membrane association of the protein after which the BH3 peptide becomes free. From simulations, Bcl-xL appears to be auto-inhibited by its C-terminal tail that embeds into and covers the hydrophobic binding pocket. However the tail is unable to energetically compete with BH3-peptides in water. In contrast, in the membrane, neither the tail nor the BH3-peptides are stable in the binding pocket and appear to be easily dissociated off as the pocket expands in response to the hydrophobic environment. This renders the binding pocket large and open, thus receptive to interactions with other protein partners. Principal components of the motions are dramatically different in the aqueous and in the membrane environments and provide clues regarding the conformational transitions that Bcl-xL undergoes in the membrane, in agreement with the biochemical data.
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Affiliation(s)
- Atanu Maity
- Bioinformatics Centre, Bose Institute, Kolkata, West Bengal, India
| | - Seema Yadav
- Bioinformatics Centre, Bose Institute, Kolkata, West Bengal, India
| | - Chandra S. Verma
- Bioinformatics Institute, Agency for Science, Technology and Research, Singapore, Singapore
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
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7
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Bhat V, Olenick MB, Schuchardt BJ, Mikles DC, Deegan BJ, McDonald CB, Seldeen KL, Kurouski D, Faridi MH, Shareef MM, Gupta V, Lednev IK, Farooq A. Heat-induced fibrillation of BclXL apoptotic repressor. Biophys Chem 2013; 179:12-25. [PMID: 23714425 DOI: 10.1016/j.bpc.2013.04.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Revised: 04/24/2013] [Accepted: 04/30/2013] [Indexed: 12/18/2022]
Abstract
The BclXL apoptotic repressor bears the propensity to associate into megadalton oligomers in solution, particularly under acidic pH. Herein, using various biophysical methods, we analyze the effect of temperature on the oligomerization of BclXL. Our data show that BclXL undergoes irreversible aggregation and assembles into highly-ordered rope-like homogeneous fibrils with length in the order of mm and a diameter in the μm-range under elevated temperatures. Remarkably, the formation of such fibrils correlates with the decay of a largely α-helical fold into a predominantly β-sheet architecture of BclXL in a manner akin to the formation of amyloid fibrils. Further interrogation reveals that while BclXL fibrils formed under elevated temperatures show no observable affinity toward BH3 ligands, they appear to be optimally primed for insertion into cardiolipin bicelles. This salient observation strongly argues that BclXL fibrils likely represent an on-pathway intermediate for insertion into mitochondrial outer membrane during the onset of apoptosis. Collectively, our study sheds light on the propensity of BclXL to form amyloid-like fibrils with important consequences on its mechanism of action in gauging the apoptotic fate of cells in health and disease.
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Affiliation(s)
- Vikas Bhat
- Department of Biochemistry & Molecular Biology, Leonard Miller School of Medicine, University of Miami, Miami, FL 33136, USA
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8
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Dürr UH, Soong R, Ramamoorthy A. When detergent meets bilayer: birth and coming of age of lipid bicelles. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2013; 69:1-22. [PMID: 23465641 PMCID: PMC3741677 DOI: 10.1016/j.pnmrs.2013.01.001] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2012] [Accepted: 08/30/2012] [Indexed: 05/12/2023]
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9
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McNally MA, Soane L, Roelofs BA, Hartman AL, Hardwick JM. The N-terminal helix of Bcl-xL targets mitochondria. Mitochondrion 2013; 13:119-24. [PMID: 23333404 DOI: 10.1016/j.mito.2013.01.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2012] [Revised: 12/16/2012] [Accepted: 01/07/2013] [Indexed: 11/26/2022]
Abstract
Anti- and pro-apoptotic Bcl-2 family members regulate the mitochondrial phase of apoptotic cell death. The mitochondrial targeting mechanisms of Bcl-2 family proteins are tightly regulated. Known outer mitochondrial membrane targeting sequences include the C-terminal tail and central helical hairpin. Bcl-xL also localizes to the inner mitochondrial membrane, but these targeting sequences are unknown. Here we investigate the possibility that the N-terminus of Bcl-xL also contains mitochondrial targeting information. Amino acid residues 1-28 of Bcl-xL fused to EGFP are sufficient to target mitochondria. Although positive charges and helical propensity are required for targeting, similar to import sequences the N-terminus is not sufficient for efficient mitochondrial import.
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Affiliation(s)
- Melanie A McNally
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins University, Bloomberg School of Public Health, Baltimore, MD 21205, USA.
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10
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Dürr UN, Gildenberg M, Ramamoorthy A. The magic of bicelles lights up membrane protein structure. Chem Rev 2012; 112:6054-74. [PMID: 22920148 PMCID: PMC3497859 DOI: 10.1021/cr300061w] [Citation(s) in RCA: 266] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Indexed: 12/12/2022]
Affiliation(s)
| | - Melissa Gildenberg
- Biophysics
and Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055,
United States
| | - Ayyalusamy Ramamoorthy
- Biophysics
and Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055,
United States
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11
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Bhat V, Kurouski D, Olenick MB, McDonald CB, Mikles DC, Deegan BJ, Seldeen KL, Lednev IK, Farooq A. Acidic pH promotes oligomerization and membrane insertion of the BclXL apoptotic repressor. Arch Biochem Biophys 2012; 528:32-44. [PMID: 22960132 DOI: 10.1016/j.abb.2012.08.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Revised: 08/19/2012] [Accepted: 08/20/2012] [Indexed: 01/03/2023]
Abstract
Solution pH is believed to serve as an intricate regulatory switch in the induction of apoptosis central to embryonic development and cellular homeostasis. Herein, using an array of biophysical techniques, we provide evidence that acidic pH promotes the assembly of BclXL apoptotic repressor into a megadalton oligomer with a plume-like appearance and harboring structural features characteristic of a molten globule. Strikingly, our data reveal that pH tightly modulates not only oligomerization but also ligand binding and membrane insertion of BclXL in a highly subtle manner. Thus, while oligomerization and the accompanying molten globular content of BclXL is least favorable at pH 6, both of these structural features become more pronounced under acidic and alkaline conditions. However, membrane insertion of BclXL appears to be predominantly favored under acidic conditions. In a remarkable contrast, while ligand binding to BclXL optimally occurs at pH 6, it is diminished by an order of magnitude at lower and higher pH. This reciprocal relationship between BclXL oligomerization and ligand binding lends new insights into how pH modulates functional versatility of a key apoptotic regulator and strongly argues that the molten globule may serve as an intermediate primed for membrane insertion in response to apoptotic cues.
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Affiliation(s)
- Vikas Bhat
- Department of Biochemistry and Molecular Biology, Leonard Miller School of Medicine, University of Miami, Miami, FL 33136, USA
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12
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Rodriguez Camargo DC, Link NM, Dames SA. The FKBP–Rapamycin Binding Domain of Human TOR Undergoes Strong Conformational Changes in the Presence of Membrane Mimetics with and without the Regulator Phosphatidic Acid. Biochemistry 2012; 51:4909-21. [DOI: 10.1021/bi3002133] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
| | - Nina M. Link
- Biozentrum, University of Basel, Basel, Switzerland
| | - Sonja A. Dames
- Biomolecular
NMR Spectroscopy,
Department of Chemistry, Technische Universität München, Munich, Germany
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