1
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Gupta LK, Molla J, Prabhu AA. Story of Pore-Forming Proteins from Deadly Disease-Causing Agents to Modern Applications with Evolutionary Significance. Mol Biotechnol 2024; 66:1327-1356. [PMID: 37294530 DOI: 10.1007/s12033-023-00776-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Accepted: 05/21/2023] [Indexed: 06/10/2023]
Abstract
Animal venoms are a complex mixture of highly specialized toxic molecules. Among them, pore-forming proteins (PFPs) or toxins (PFTs) are one of the major disease-causing toxic elements. The ability of the PFPs in defense and toxicity through pore formation on the host cell surface makes them unique among the toxin proteins. These features made them attractive for academic and research purposes for years in the areas of microbiology as well as structural biology. All the PFPs share a common mechanism of action for the attack of host cells and pore formation in which the selected pore-forming motifs of the host cell membrane-bound protein molecules drive to the lipid bilayer of the cell membrane and eventually produces water-filled pores. But surprisingly their sequence similarity is very poor. Their existence can be seen both in a soluble state and also in transmembrane complexes in the cell membrane. PFPs are prevalent toxic factors that are predominately produced by all kingdoms of life such as virulence bacteria, nematodes, fungi, protozoan parasites, frogs, plants, and also from higher organisms. Nowadays, multiple approaches to applications of PFPs have been conducted by researchers both in basic as well as applied biological research. Although PFPs are very devastating for human health nowadays researchers have been successful in making these toxic proteins into therapeutics through the preparation of immunotoxins. We have discussed the structural, and functional mechanism of action, evolutionary significance through dendrogram, domain organization, and practical applications for various approaches. This review aims to emphasize the PFTs to summarize toxic proteins together for basic knowledge as well as to highlight the current challenges, and literature gap along with the perspective of promising biotechnological applications for their future research.
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Affiliation(s)
- Laxmi Kumari Gupta
- Bioprocess Development Laboratory, Department of Biotechnology, National Institute of Technology Warangal, Warangal, Telangana, 506004, India
| | - Johiruddin Molla
- Ghatal Rabindra Satabarsiki Mahavidyalaya Ghatal, Paschim Medinipur, Ghatal, West Bengal, 721212, India
| | - Ashish A Prabhu
- Bioprocess Development Laboratory, Department of Biotechnology, National Institute of Technology Warangal, Warangal, Telangana, 506004, India.
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2
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Mushtaq AU, Ådén J, Ali K, Gröbner G. Domain-specific insight into the recognition of BH3-death motifs by the pro-survival Bcl-2 protein. Biophys J 2022; 121:4517-4525. [PMID: 36325615 PMCID: PMC9748362 DOI: 10.1016/j.bpj.2022.10.041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2022] [Revised: 10/09/2022] [Accepted: 10/27/2022] [Indexed: 11/07/2022] Open
Abstract
Programmed mammalian cell death (apoptosis) is an essential mechanism in life that tightly regulates embryogenesis and removal of dysfunctional cells. In its intrinsic (mitochondrial) pathway, opposing members of the Bcl-2 (B cell lymphoma 2) protein family meet at the mitochondrial outer membrane (MOM) to control its integrity. Any imbalance can cause disorders, with upregulation of the cell-guarding antiapoptotic Bcl-2 protein itself being common in many, often incurable, cancers. Normally, the Bcl-2 protein itself is embedded in the MOM where it sequesters cell-killing apoptotic proteins such as Bax (Bcl-2-associated X protein) that would otherwise perforate the MOM and subsequently cause cell death. However, the molecular basis of Bcl-2's ability to recognize those apoptotic proteins via their common BH3 death motifs remains elusive due to the lack of structural insight. By employing nuclear magnetic resonance on fully functional human Bcl-2 protein in membrane-mimicking micelles, we identified glycine residues across all functional domains of the Bcl-2 protein and could monitor their residue-specific individual response upon the presence of a Bax-derived 36aa long BH3 domain. The observed chemical shift perturbations allowed us to determine the response and individual affinity of each glycine residue and provide an overall picture of the individual roles by which Bcl-2's functional domains engage in recognizing and inhibiting apoptotic proteins via their prominent BH3 motifs. This way, we provide a unique residue- and domain-specific insight into the molecular functioning of Bcl-2 at the membrane level, an insight also opening up for interfering with this cell-protecting mechanism in cancer therapy.
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Affiliation(s)
| | - Jörgen Ådén
- Department of Chemistry, University of Umeå, Umeå, Sweden
| | - Katan Ali
- Department of Chemistry, University of Umeå, Umeå, Sweden
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3
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Gelles JD, Mohammed JN, Chen Y, Sebastian TM, Chipuk JE. A kinetic fluorescence polarization ligand assay for monitoring BAX early activation. CELL REPORTS METHODS 2022; 2:100174. [PMID: 35419554 PMCID: PMC9004659 DOI: 10.1016/j.crmeth.2022.100174] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 12/20/2021] [Accepted: 02/02/2022] [Indexed: 12/23/2022]
Abstract
Developmental, homeostatic, and pharmacological pro-apoptotic signals converge by activating the BCL-2 family member BAX. Studies investigating molecular regulation of BAX are commonly limited to methodologies measuring endpoint phenotypes and do not assess activation of monomeric BAX. Here, we present FLAMBE, a fluorescence polarization ligand assay for monitoring BAX early activation, that measures activation-induced release of a peptide probe in real time. Using complementary parallel and tandem biochemical techniques, we validate, corroborate, and apply FLAMBE to a contemporary repertoire of BAX modulators, characterizing their contributions within the early steps of BAX activation. Additionally, we use FLAMBE to reveal that historically "dead" BAX mutants remain responsive to activation as quasi-functional monomers. We also identify data metrics for comparative analyses and demonstrate that FLAMBE data align with downstream functional observations. Collectively, FLAMBE advances our understanding of BAX activation and fills a methodological void for studying BAX with broad applications in cell biology and therapeutic development. MOTIVATION In vitro BAX activation studies are invaluable platforms for studying cellular and pharmacological modulators of apoptosis. The gold standard for studying BAX function relies on membrane permeabilization assays, which assess the pore-forming activity of oligomeric BAX. However, there are currently no rapid or kinetic assays to interrogate real-time activation of monomeric BAX in solution, thereby limiting any molecular insights that occur upstream of mitochondrial permeabilization. Furthermore, available methods to observe the activation of monomeric BAX suffer from low throughput and static observations. To address this methodological gap, we developed FLAMBE, a kinetic fluorescence polarization-based assay to measure monomeric BAX activation in solution via concomitant displacement of a labeled peptide. This approach maintains the benefits of rapid kinetic data generation in a low-cost microplate format without requiring specialized equipment or large quantities of protein. FLAMBE compliments available experimental strategies and expands the accessibility of investigators to monitor early steps within the BAX activation continuum.
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Affiliation(s)
- Jesse D. Gelles
- Laboratory of Mitochondrial Biology in Human Health and Disease, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
- Department of Dermatology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
- The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Jarvier N. Mohammed
- Laboratory of Mitochondrial Biology in Human Health and Disease, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
- Department of Dermatology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
- The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
- The Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Yiyang Chen
- Laboratory of Mitochondrial Biology in Human Health and Disease, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
- Department of Dermatology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
- The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
- The Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Tara M. Sebastian
- Laboratory of Mitochondrial Biology in Human Health and Disease, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
- The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Jerry Edward Chipuk
- Laboratory of Mitochondrial Biology in Human Health and Disease, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
- Department of Dermatology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
- The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
- The Diabetes, Obesity, and Metabolism Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
- The Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
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4
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Abstract
The proteins of the Bcl-2 family regulate apoptosis by forming a complex interaction network whose output determines whether mitochondrial outer membrane permeabilization is executed. Quantification of complex formation between Bcl-2 proteins in solution and in membranes is therefore key to understand how the hierarchy of interactions controls cell death induction. Fluorescence correlation spectroscopy (FCS) is a noninvasive, nondestructive method to investigate the mobility and the association of fluorescently labeled biomolecules that has provided useful insight into the binding affinity of the Bcl-2 interactome. FCS is based on the detection of fluorescence fluctuations caused by the diffusion of individual molecules through a very tiny observation volume of the detection system. Scanning FCS (SFCS) solves some of the practical challenges of acquiring FCS in membranes and expands the application scope of the method. In this chapter, we explain the principle of FCS and describe protocols how it can be used to quantify interactions between Bcl-2 proteins in solution and in model membrane systems.
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5
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Pang SW, Lahiri C, Poh CL, Tan KO. PNMA family: Protein interaction network and cell signalling pathways implicated in cancer and apoptosis. Cell Signal 2018; 45:54-62. [PMID: 29378289 DOI: 10.1016/j.cellsig.2018.01.022] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Revised: 01/23/2018] [Accepted: 01/23/2018] [Indexed: 12/22/2022]
Abstract
Paraneoplastic Ma Family (PNMA) comprises a growing number of family members which share relatively conserved protein sequences encoded by the human genome and is localized to several human chromosomes, including the X-chromosome. Based on sequence analysis, PNMA family members share sequence homology to the Gag protein of LTR retrotransposon, and several family members with aberrant protein expressions have been reported to be closely associated with the human Paraneoplastic Disorder (PND). In addition, gene mutations of specific members of PNMA family are known to be associated with human mental retardation or 3-M syndrome consisting of restrictive post-natal growth or dwarfism, and development of skeletal abnormalities. Other than sequence homology, the physiological function of many members in this family remains unclear. However, several members of this family have been characterized, including cell signalling events mediated by these proteins that are associated with apoptosis, and cancer in different cell types. Furthermore, while certain PNMA family members show restricted gene expression in the human brain and testis, other PNMA family members exhibit broader gene expression or preferential and selective protein interaction profiles, suggesting functional divergence within the family. Functional analysis of some members of this family have identified protein domains that are required for subcellular localization, protein-protein interactions, and cell signalling events which are the focus of this review paper.
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Affiliation(s)
- Siew Wai Pang
- Department of Biological Sciences, Sunway University, Bandar Sunway, 47500, Selangor Darul Ehsan, Malaysia
| | - Chandrajit Lahiri
- Department of Biological Sciences, Sunway University, Bandar Sunway, 47500, Selangor Darul Ehsan, Malaysia
| | - Chit Laa Poh
- Research Centre for Biomedical Sciences, Sunway University, Bandar Sunway, 47500, Selangor Darul Ehsan, Malaysia
| | - Kuan Onn Tan
- Department of Biological Sciences, Sunway University, Bandar Sunway, 47500, Selangor Darul Ehsan, Malaysia.
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6
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Kao TY, Tsai CJ, Lan YJ, Chiang YW. The role of conformational heterogeneity in regulating the apoptotic activity of BAX protein. Phys Chem Chem Phys 2017; 19:9584-9591. [DOI: 10.1039/c7cp00401j] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Inactive BAX exists in two states. A shift in the equilibrium would initiate apoptosis.
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Affiliation(s)
- Te-Yu Kao
- Department of Chemistry
- National Tsing Hua University
- Hsinchu 30013
- Taiwan
| | - Chia-Jung Tsai
- Department of Chemistry
- National Tsing Hua University
- Hsinchu 30013
- Taiwan
| | - Yu-Jing Lan
- Department of Chemistry
- National Tsing Hua University
- Hsinchu 30013
- Taiwan
| | - Yun-Wei Chiang
- Department of Chemistry
- National Tsing Hua University
- Hsinchu 30013
- Taiwan
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7
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Cosentino K, García-Sáez AJ. Bax and Bak Pores: Are We Closing the Circle? Trends Cell Biol 2016; 27:266-275. [PMID: 27932064 DOI: 10.1016/j.tcb.2016.11.004] [Citation(s) in RCA: 135] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 10/28/2016] [Accepted: 11/07/2016] [Indexed: 01/19/2023]
Abstract
Bax and its homolog Bak are key regulators of the mitochondrial pathway of apoptosis. On cell stress Bax and Bak accumulate at distinct foci on the mitochondrial surface where they undergo a conformational change, oligomerize, and mediate cytochrome c release, leading to cell death. The molecular mechanisms of Bax and Bak assembly and mitochondrial permeabilization have remained a longstanding question in the field. Recent structural and biophysical studies at several length scales have shed light on key aspects of Bax and Bak function that have shifted how we think this process occurs. These discoveries reveal an unexpected molecular mechanism in which Bax (and likely Bak) dimers assemble into oligomers with an even number of molecules that fully or partially delineate pores of different sizes to permeabilize the mitochondrial outer membrane (MOM) during apoptosis.
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Affiliation(s)
- Katia Cosentino
- Interfaculty Institute of Biochemistry, University of Tübingen, Hoppe-Seyler-Str. 4, 72076 Tübingen, Germany
| | - Ana J García-Sáez
- Interfaculty Institute of Biochemistry, University of Tübingen, Hoppe-Seyler-Str. 4, 72076 Tübingen, Germany; Max Planck Institute for Intelligent Systems, Heisenbergstr. 3, Stuttgart, Germany.
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8
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Cooley-Andrade O, Goh W, Connor D, Ma D, Parsi K. Detergent Sclerosants Stimulate Leukocyte Apoptosis and Oncosis. Eur J Vasc Endovasc Surg 2016; 51:846-56. [DOI: 10.1016/j.ejvs.2016.03.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Accepted: 03/08/2016] [Indexed: 11/30/2022]
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9
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Hill RB, MacKenzie KR, Harwig MC. The Tail-End Is Only the Beginning: NMR Study Reveals a Membrane-Bound State of BCL-XL. J Mol Biol 2015; 427:2257-61. [PMID: 25896456 DOI: 10.1016/j.jmb.2015.04.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- R Blake Hill
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Kevin R MacKenzie
- Department of Biology and Biochemistry, University of Houston, Houston, TX 77004, USA
| | - Megan Cleland Harwig
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI 53226, USA
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10
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Cooley-Andrade O, Connor DE, Ma DDF, Weisel JW, Parsi K. Morphological changes in vascular and circulating blood cells following exposure to detergent sclerosants. Phlebology 2015; 31:177-91. [DOI: 10.1177/0268355515573686] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Objectives To investigate morphological changes in vascular and circulating blood cells following exposure to detergent sclerosants sodium tetradecyl sulfate and polidocanol. Methods Samples of whole blood, isolated leukocytes, platelets, endothelial cells, and fibroblasts were incubated with varying concentrations of sclerosants. Whole blood smears were stained with Giemsa and examined by light and bright field microscopy. Phalloidin and Hoechst stains were used to analyze cytoplasmic and nuclear morphology by fluorescence microscopy. Endothelial cell and fibroblasts were analyzed by live cell imaging. Results Higher concentrations of sclerosants induced cell lysis. Morphological changes in intact cells were observed at sublytic concentrations of detergents. Low concentration sodium tetradecyl sulfate induced erythrocyte acanthocytosis and macrocytosis, while polidocanol induced Rouleaux formation and increased the population of target cells and stomatocytes. Leukocytes showed swelling, blebbing, vacuolation, and nuclear degradation following exposure to sodium tetradecyl sulfate, while polidocanol induced pseudopodia formation, chromatin condensation, and fragmentation. Platelets exhibited pseudopodia with sodium tetradecyl sulfate and a “fried egg” appearance with polidocanol. Exposure to sodium tetradecyl sulfate resulted in size shrinkage in both endothelial cell and fibroblasts, while endothelial cell developed distinct spindle morphology. Polidocanol induced cytoplasmic microfilament bundles in both endothelial cell and fibroblasts. Patchy chromatin condensation was observed following exposure of fibroblasts to either agent. Conclusion Detergent sclerosants are biologically active at sublytic concentrations. The observed morphological changes are consistent with cell activation, apoptosis, and oncosis. The cellular response is concentration dependent, cell-specific, and sclerosant specific.
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Affiliation(s)
- O Cooley-Andrade
- Dermatology, Phlebology and Fluid Mechanics Research Laboratory, St Vincent’s Centre for Applied Medical Research (AMR), St. Vincent’s Hospital, Sydney, Australia
- The University of New South Wales, Sydney, Australia
| | - DE Connor
- Dermatology, Phlebology and Fluid Mechanics Research Laboratory, St Vincent’s Centre for Applied Medical Research (AMR), St. Vincent’s Hospital, Sydney, Australia
- The University of New South Wales, Sydney, Australia
| | - DDF Ma
- Haematology Research Laboratory, St Vincent’s Centre for Applied Medical Research (AMR), St. Vincent’s Hospital, Sydney, Australia
| | - JW Weisel
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - K Parsi
- Dermatology, Phlebology and Fluid Mechanics Research Laboratory, St Vincent’s Centre for Applied Medical Research (AMR), St. Vincent’s Hospital, Sydney, Australia
- The University of New South Wales, Sydney, Australia
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11
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Rouse SL, Sansom MSP. Interactions of lipids and detergents with a viral ion channel protein: molecular dynamics simulation studies. J Phys Chem B 2014; 119:764-72. [PMID: 25286030 PMCID: PMC4306293 DOI: 10.1021/jp505127y] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
![]()
Structural
studies of membrane proteins have highlighted the likely
influence of membrane mimetic environments (i.e., lipid bilayers versus
detergent micelles) on the conformation and dynamics of small α-helical
membrane proteins. We have used molecular dynamics simulations to
compare the conformational dynamics of BM2 (a small α-helical
protein from the membrane of influenza B) in a model phospholipid
bilayer environment with its behavior in protein–detergent
complexes with either the zwitterionic detergent dihexanoylphosphatidylcholine
(DHPC) or the nonionic detergent dodecylmaltoside (DDM). We find that
DDM more closely resembles the lipid bilayer in terms of its interaction
with the protein, while the short-tailed DHPC molecule forms “nonphysiological”
interactions with the protein termini. We find that the intrinsic
micelle properties of each detergent are conserved upon formation
of the protein–detergent complex. This implies that simulations
of detergent micelles may be used to help select optimal conditions
for experimental studies of membrane proteins.
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Affiliation(s)
- Sarah L Rouse
- Department of Biochemistry, University of Oxford , South Parks Road, Oxford OX1 3QU, United Kingdom
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12
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Abstract
The field of mitochondrial ion channels has recently seen substantial progress, including the molecular identification of some of the channels. An integrative approach using genetics, electrophysiology, pharmacology, and cell biology to clarify the roles of these channels has thus become possible. It is by now clear that many of these channels are important for energy supply by the mitochondria and have a major impact on the fate of the entire cell as well. The purpose of this review is to provide an up-to-date overview of the electrophysiological properties, molecular identity, and pathophysiological functions of the mitochondrial ion channels studied so far and to highlight possible therapeutic perspectives based on current information.
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13
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Yao S, Westphal D, Babon JJ, Thompson GV, Robin AY, Adams JM, Colman PM, Czabotar PE. NMR studies of interactions between Bax and BH3 domain-containing peptides in the absence and presence of CHAPS. Arch Biochem Biophys 2014; 545:33-43. [PMID: 24434006 DOI: 10.1016/j.abb.2014.01.003] [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: 10/29/2013] [Revised: 12/26/2013] [Accepted: 01/06/2014] [Indexed: 01/27/2023]
Abstract
Activation and oligomerisation of Bax, a key pro-apoptotic Bcl-2 family protein, are key steps in the mitochondrial pathway to apoptosis. The signals for apoptosis are conveyed by the distantly related BH3-only proteins, which use their short BH3 domain, an amphipathic α-helix, to interact with other Bcl-2 family members. Here we report an NMR study of interactions between BaxΔC and BH3 domain-containing peptides in the absence and presence of CHAPS, a zwitterionic detergent. We find for the first time that CHAPS interacts weakly with BaxΔC (fast exchange on the NMR chemical shift timescale), at concentrations below micelle formation and with an estimated Kd in the tens of mM. Direct and relatively strong-interactions (slow exchange on the NMR chemical shift timescale) were also observed for BaxΔC with BaxBH3 (estimated Kd of circa 150μM) or BimBH3 in the absence of CHAPS. The interaction with either peptide alone induced widespread chemical shift perturbations to BaxΔC in solution which implies that BaxΔC might have undergone significant conformation change upon binding the BH3 peptide. However, BaxΔC remained monomeric upon binding either CHAPS or a BH3 peptide alone, but the presence of both provoked it to form a dimer.
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Affiliation(s)
- Shenggen Yao
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; Department of Medical Biology, The University of Melbourne, Victoria 3010, Australia; Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria 3010, Australia.
| | - Dana Westphal
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; Department of Medical Biology, The University of Melbourne, Victoria 3010, Australia
| | - Jeffrey J Babon
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; Department of Medical Biology, The University of Melbourne, Victoria 3010, Australia
| | - Geoff V Thompson
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
| | - Adeline Y Robin
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; Department of Medical Biology, The University of Melbourne, Victoria 3010, Australia
| | - Jerry M Adams
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; Department of Medical Biology, The University of Melbourne, Victoria 3010, Australia
| | - Peter M Colman
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; Department of Medical Biology, The University of Melbourne, Victoria 3010, Australia
| | - Peter E Czabotar
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; Department of Medical Biology, The University of Melbourne, Victoria 3010, Australia.
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14
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Abstract
Fluorescence cross-correlation spectroscopy (FCCS) is a single-molecule sensitive technique to quantitatively study interactions among fluorescently tagged biomolecules. Besides the initial implementation as dual-color FCCS (DC-FCCS), FCCS has several powerful derivatives, including single-wavelength FCCS (SW-FCCS), two-photon FCCS (TP-FCCS), and pulsed interleaved excitation FCCS (PIE-FCCS). However, to apply FCCS successfully, one needs to be familiar with procedures ranging from fluorescent labeling, instrumentation setup and alignment, sample preparation, and data analysis. Here, we describe the procedures to apply FCCS in various biological samples ranging from live cells to in vivo measurements, with the focus on DC-FCCS and SW-FCCS.
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15
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Wallgren M, Lidman M, Pedersen A, Brännström K, Karlsson BG, Gröbner G. Reconstitution of the anti-apoptotic Bcl-2 protein into lipid membranes and biophysical evidence for its detergent-driven association with the pro-apoptotic Bax protein. PLoS One 2013; 8:e61452. [PMID: 23626686 PMCID: PMC3634071 DOI: 10.1371/journal.pone.0061452] [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: 11/22/2012] [Accepted: 03/10/2013] [Indexed: 11/18/2022] Open
Abstract
The anti-apoptotic B-cell CLL/lymphoma-2 (Bcl-2) protein and its counterpart, the pro-apoptotic Bcl-2-associated X protein (Bax), are key players in the regulation of the mitochondrial pathway of apoptosis. However, how they interact at the mitochondrial outer membrane (MOM) and there determine whether the cell will live or be sentenced to death remains unknown. Competing models have been presented that describe how Bcl-2 inhibits the cell-killing activity of Bax, which is common in treatment-resistant tumors where Bcl-2 is overexpressed. Some studies suggest that Bcl-2 binds directly to and sequesters Bax, while others suggest an indirect process whereby Bcl-2 blocks BH3-only proteins and prevents them from activating Bax. Here we present the results of a biophysical study in which we investigated the putative interaction of solubilized full-length human Bcl-2 with Bax and the scope for incorporating the former into a native-like lipid environment. Far-UV circular dichroism (CD) spectroscopy was used to detect direct Bcl-2-Bax-interactions in the presence of polyoxyethylene-(23)-lauryl-ether (Brij-35) detergent at a level below its critical micelle concentration (CMC). Additional surface plasmon resonance (SPR) measurements confirmed this observation and revealed a high affinity between the Bax and Bcl-2 proteins. Upon formation of this protein-protein complex, Bax also prevented the binding of antimycin A2 (a known inhibitory ligand of Bcl-2) to the Bcl-2 protein, as fluorescence spectroscopy experiments showed. In addition, Bcl-2 was able to form mixed micelles with Triton X-100 solubilized neutral phospholipids in the presence of high concentrations of Brij-35 (above its CMC). Following detergent removal, the integral membrane protein was found to have been fully reconstituted into a native-like membrane environment, as confirmed by ultracentrifugation and subsequent SDS-PAGE experiments.
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Affiliation(s)
| | - Martin Lidman
- Department of Chemistry, Umeå University, Umeå, Sweden
| | - Anders Pedersen
- Swedish NMR Centre, University of Gothenburg, Gothenburg, Sweden
| | | | | | - Gerhard Gröbner
- Department of Chemistry, Umeå University, Umeå, Sweden
- * E-mail:
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16
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Bax induces cytochrome c release by multiple mechanisms in mitochondria from MCF7 cells. J Bioenerg Biomembr 2013; 45:441-8. [PMID: 23536162 DOI: 10.1007/s10863-013-9508-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Accepted: 03/14/2013] [Indexed: 10/27/2022]
Abstract
Bax, a pro-apoptotic member of the Bcl-2 family of proteins has the ability to form transmembrane pores large enough to allow cytochrome c (Cyt c) release, as well as to activate the mitochondrial permeability transition pore (mPTP); however, no differential study has been conducted to clarify which one of these mechanisms predominates over the other in the same system. In the present study, we treated isolated mitochondria from MCF7 cells with recombinant protein Bax and tested the efficacy of the mPTP inhibitor cyclosporin A (CsA) and of the Bax channel blocker (Bcb) to inhibit cytochrome c release. We also, induced apoptosis in MCF7 cell cultures with TNF-α plus cycloheximide to determine the effect of such compounds in apoptosis induction via mPTP or Bax oligomerization. Cytochrome c release was totally prevented by CsA and partially by Bcb when apoptosis was induced with recombinant Bax in isolated mitochondria from MCF7 cells. CsA increased the number of living cells in cell culture, as compared with the effect of Bax channel blocker. These results indicate that mPTP activation is the predominant pathway for Bax-induced cytochrome c release from MCF7 mitochondria and for apoptosis induction in the whole cell.
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Wakeman D, Guo J, Santos JA, Wandu WS, Schneider JE, McMellen ME, Leinicke JA, Erwin CR, Warner BW. p38 MAPK regulates Bax activity and apoptosis in enterocytes at baseline and after intestinal resection. Am J Physiol Gastrointest Liver Physiol 2012; 302:G997-1005. [PMID: 22383494 PMCID: PMC3362074 DOI: 10.1152/ajpgi.00485.2011] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Accepted: 02/27/2012] [Indexed: 01/31/2023]
Abstract
Increased apoptosis in crypt enterocytes is a key feature of intestinal adaptation following massive small bowel resection (SBR). Expression of the proapoptotic factor Bax has been shown to be required for resection-induced apoptosis. It has also been demonstrated that p38-α MAPK (p38) is necessary for Bax activation and apoptosis in vitro. The present studies were designed to test the hypothesis that p38 is a key regulator of Bax activation during adaptation after SBR in vivo. Enterocyte expression of p38 was deleted by tamoxifen administration to activate villin-Cre in adult mice with a floxed Mapk14 (p38-α) gene. Proximal 50% SBR or sham operations were performed on wild-type (WT) and p38 intestinal knockout (p38-IKO) mice under isoflurane anesthesia. Mice were killed 3 or 7 days after operation, and adaptation was analyzed by measuring intestinal morphology, proliferation, and apoptosis. Bax activity was quantified by immunoprecipitation, followed by Western blotting. After SBR, p38-IKO mice had deeper crypts, longer villi, and accelerated proliferation compared with WT controls. Rates of crypt apoptosis were significantly lower in p38-IKO mice, both at baseline and after SBR. Levels of activated Bax were twofold higher in WT mice after SBR relative to sham. In contrast, activated Bax levels were reduced by 67% in mice after p38 MAPK deletion. Deleted p38 expression within the intestinal epithelium leads to enhanced adaptation and reduced levels of enterocyte apoptosis after massive intestinal resection. p38-regulated Bax activation appears to be an important mechanism underlying resection-induced apoptosis.
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Affiliation(s)
- Derek Wakeman
- Department of Surgery, Division of Pediatric Surgery, St. Louis Children's Hospital, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Lindsay J, Esposti MD, Gilmore AP. Bcl-2 proteins and mitochondria--specificity in membrane targeting for death. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1813:532-9. [PMID: 21056595 DOI: 10.1016/j.bbamcr.2010.10.017] [Citation(s) in RCA: 215] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2010] [Revised: 10/22/2010] [Accepted: 10/27/2010] [Indexed: 01/10/2023]
Abstract
The localization and control of Bcl-2 proteins on mitochondria is essential for the intrinsic pathway of apoptosis. Anti-apoptotic Bcl-2 proteins reside on the outer mitochondrial membrane (OMM) and prevent apoptosis by inhibiting the activation of the pro-apoptotic family members Bax and Bak. The Bcl-2 subfamily of BH3-only proteins can either inhibit the anti-apoptotic proteins or directly activate Bax or Bak. How these proteins interact with each other, the mitochondrial surface and within the OMM are complex processes we are only beginning to understand. However, these interactions are fundamental for the transduction of apoptotic signals to mitochondria and the subsequent release of caspase activating factors into the cytosol. In this review we will discuss our knowledge of how Bcl-2 proteins are directed to mitochondria in the first place, a crucial but poorly understood aspect of their regulation. This article is part of a Special Issue entitled Mitochondria: the deadly organelle.
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Affiliation(s)
- Jennefer Lindsay
- Wellcome Trust Centre for Cell Matrix Research, Faculty of Life Sciences The University of Manchester, UK.
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Liu Q, Gehring K. Heterodimerization of BAK and MCL-1 activated by detergent micelles. J Biol Chem 2010; 285:41202-10. [PMID: 21036904 DOI: 10.1074/jbc.m110.144857] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
BAK is a key protein mediating mitochondrial outer membrane permeabilization; however, its behavior in the membrane is poorly understood. Here, we characterize the conformational changes in BAK and MCL-1 using detergents to mimic the membrane environment and study their interaction by in vitro pulldown experiments, size exclusion chromatography, titration calorimetry, and NMR spectroscopy. The nonionic detergent IGEPAL has little impact on the structure of MCL-1 but induces a conformational change in BAK, whereby its BH3 region is able to engage the hydrophobic groove of MCL-1. Although the zwitterionic detergent CHAPS induces only minor conformational changes in both proteins, it is still able to initiate heterodimerization. The complex of MCL-1 and BAK can be disrupted by a BID-BH3 peptide, which acts through binding to MCL-1, but a mutant peptide, BAK-BH3-L78A, with low affinity for MCL-1 failed to dissociate the complex. The mutation L78A in BAK prevented binding to MCL-1, thus demonstrating the essential role of the BH3 region of BAK in its regulation by MCL-1. Our results validate the current models for the activation of BAK and highlight the potential value of small molecule inhibitors that target MCL-1 directly.
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Affiliation(s)
- Qian Liu
- Department of Biochemistry, McGill University, Montreal, Quebec H3G 0B1, Canada
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Leber B, Lin J, Andrews DW. Still embedded together binding to membranes regulates Bcl-2 protein interactions. Oncogene 2010; 29:5221-30. [PMID: 20639903 PMCID: PMC6459407 DOI: 10.1038/onc.2010.283] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2010] [Revised: 05/27/2010] [Accepted: 06/04/2010] [Indexed: 12/19/2022]
Abstract
The dysregulation of apoptosis is a key step in developing tumours, and mediates resistance to cancer therapy. Many different signals for cell death converge on permeabilization of the outer mitochondrial membrane, which is controlled by the Bcl-2 family of proteins. The importance of this step is becoming increasingly relevant as the first generation of small molecules that inhibit the interaction of Bcl-2 family proteins enters clinical trials as anticancer agents. The Bcl-2 family can be divided into three classes: BH3-only proteins that are activated by various forms of cellular stress, Bax and Bak proteins that mediate mitochondrial membrane permeabilization, and inhibitory proteins such as Bcl-2 and Bcl-XL. The recently proposed embedded together model emphasizes the fact that many of the regulatory interactions between different classes of Bcl-2 family members occur at intracellular membranes, and binding to membranes causes conformational changes in the proteins that dictate functions in a dynamic manner. Within this context, recent results indicate that Bcl-XL functions as a dominant-negative Bax, a concept that resolves the paradox of similar structures but opposite functions of Bcl-XL and Bax. We have also shown that the conformational change that allows Bax to insert into the outer mitochondrial membrane is the rate-limiting step in the multistep process of Bax activation. Nevertheless, investigating the structure of activated Bax or Bak as monomers and as components of the oligomeric structures that mediate membrane permeabilization is the focus of ongoing research (and controversy) at many laboratories worldwide.
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Affiliation(s)
- B Leber
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
- Department of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - J Lin
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - DW Andrews
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
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Borutaite V. Mitochondria as decision-makers in cell death. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2010; 51:406-416. [PMID: 20209625 DOI: 10.1002/em.20564] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Mitochondria play an essential role in both cell health and death. Increasing experimental evidence suggests that mitochondria are involved in active control of cell death processes at several levels including (1) mitochondrial membrane permeabilization and release of proapoptotic proteins, (2) post-cytochrome c regulation of caspase activation, and (3) supply of energy for execution of death program. The purpose of this review is to discuss the main mechanisms by which alterations in mitochondrial outer membrane permit the translocation of proapoptotic proteins into cytosol, how mitochondria "make decisions" on the mode of cell death, and how they regulate caspase activation by changing the redox state of cytosolic cytochrome c. The interventions into these processes may constitute an important strategy for the pharmacological prevention of unwanted cell death in various pathologies or, conversely, for facilitation of anticancer therapy.
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Affiliation(s)
- Vilmante Borutaite
- Institute for Biomedical Research, Kaunas University of Medicine, Kaunas, Lithuania.
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Zhang Z, Zhu W, Lapolla SM, Miao Y, Shao Y, Falcone M, Boreham D, McFarlane N, Ding J, Johnson AE, Zhang XC, Andrews DW, Lin J. Bax forms an oligomer via separate, yet interdependent, surfaces. J Biol Chem 2010; 285:17614-27. [PMID: 20382739 DOI: 10.1074/jbc.m110.113456] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Interactions of Bcl-2 family proteins regulate permeability of the mitochondrial outer membrane and apoptosis. In particular, Bax forms an oligomer that permeabilizes the membrane. To map the interface of the Bax oligomer we used Triton X-100 as a membrane surrogate and performed site-specific photocross-linking. Bax-specific adducts were formed through photo-reactive probes at multiple sites that can be grouped into two surfaces. The first surface overlaps with the BH1-3 groove formed by Bcl-2 Homology motif 1, 2, and 3; the second surface is a rear pocket located on the opposite side of the protein from the BH1-3 groove. Further cross-linking experiments using Bax BH3 peptides and mutants demonstrated that the two surfaces interact with their counterparts in neighboring proteins to form two separated interfaces and that interaction at the BH1-3 groove primes the rear pocket for further interaction. Therefore, Bax oligomerization proceeds through a series of interactions that occur at separate, yet allosterically, coupled interfaces.
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Affiliation(s)
- Zhi Zhang
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73126, USA
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Ganesan V, Perera MN, Colombini D, Datskovskiy D, Chadha K, Colombini M. Ceramide and activated Bax act synergistically to permeabilize the mitochondrial outer membrane. Apoptosis 2010; 15:553-62. [DOI: 10.1007/s10495-009-0449-0] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Bleicken S, Classen M, Padmavathi PVL, Ishikawa T, Zeth K, Steinhoff HJ, Bordignon E. Molecular details of Bax activation, oligomerization, and membrane insertion. J Biol Chem 2009; 285:6636-47. [PMID: 20008353 DOI: 10.1074/jbc.m109.081539] [Citation(s) in RCA: 145] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Bax and Bid are pro-apoptotic members of the Bcl-2 protein family. Upon cleavage by caspase-8, Bid activates Bax. Activated Bax inserts into the mitochondrial outer membrane forming oligomers which lead to membrane poration, release of cytochrome c, and apoptosis. The detailed mechanism of Bax activation and the topology and composition of the oligomers are still under debate. Here molecular details of Bax activation and oligomerization were obtained by application of several biophysical techniques, including atomic force microscopy, cryoelectron microscopy, and particularly electron paramagnetic resonance (EPR) spectroscopy performed on spin-labeled Bax. Incubation with detergents, reconstitution, and Bid-triggered insertion into liposomes were found to be effective in inducing Bax oligomerization. Bid was shown to activate Bax independently of the stoichiometric ratio, suggesting that Bid has a catalytic function and that the interaction with Bax is transient. The formation of a stable dimerization interface involving two Bcl-2 homology 3 (BH3) domains was found to be the nucleation event for Bax homo-oligomerization. Based on intermolecular distance determined by EPR, a model of six adjacent Bax molecules in the oligomer is presented where the hydrophobic hairpins (helices alpha5 and alpha6) are equally spaced in the membrane and the two BH3 domains are in close vicinity in the dimer interface, separated by >5 nm from the next BH3 pairs.
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Affiliation(s)
- Stephanie Bleicken
- Department of Membrane Biochemistry, Max Planck Institute for Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
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