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Yao Q, Mascarenhas Dos Santos AC, Zhang H, Mañas A, Hussaini A, Kim U, Xu C, Basheer S, Tasaki S, Xiang J. Unconventional Source of Neurotoxic Protein Aggregation from Organelle Off-Target Bax∆2 in Alzheimer's Disease. Biomolecules 2023; 13:970. [PMID: 37371550 DOI: 10.3390/biom13060970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 05/30/2023] [Accepted: 06/06/2023] [Indexed: 06/29/2023] Open
Abstract
Protein aggregates are a hallmark of Alzheimer's disease (AD). Extensive studies have focused on β-amyloid plaques and Tau tangles. Here, we illustrate a novel source of protein aggregates in AD neurons from organelle off-target proteins. Bax is a mitochondrial pore-forming pro-death protein. What happens to Bax if it fails to target mitochondria? We previously showed that a mitochondrial target-deficient alternatively spliced variant, Bax∆2, formed large cytosolic protein aggregates and triggered caspase 8-mediated cell death. Bax∆2 protein levels were low in most normal organs and the proteins were quickly degraded in cancer. Here, we found that 85% of AD patients had Bax∆2 required alternative splicing. Increased Bax∆2 proteins were mostly accumulated in neurons of AD-susceptible brain regions. Intracellularly, Bax∆2 aggregates distributed independently of Tau tangles. Interestingly, Bax∆2 aggregates triggered the formation of stress granules (SGs), a large protein-RNA complex involved in AD pathogenesis. Although the functional domains required for aggregation and cell death are the same as in cancer cells, Bax∆2 relied on SGs, not caspase 8, for neuronal cell death. These results imply that the aggregation of organelle off-target proteins, such as Bax∆2, broadens the scope of traditional AD pathogenic proteins that contribute to the neuronal stress responses and AD pathogenesis.
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Affiliation(s)
- Qi Yao
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA
| | | | - Huaiyuan Zhang
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Adriana Mañas
- Department of Laboratory Medicine, Lund University, 22381 Lund, Sweden
| | - Ammarah Hussaini
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Ujin Kim
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Congtai Xu
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Sana Basheer
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Shinya Tasaki
- Rush Alzheimer's Disease Center, Rush University Medical Center, Chicago, IL 60612, USA
| | - Jialing Xiang
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA
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2
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Remington JM, Ferrell JB, Schneebeli ST, Li J. Concerted Rolling and Penetration of Peptides during Membrane Binding. J Chem Theory Comput 2022; 18:3921-3929. [PMID: 35507824 DOI: 10.1021/acs.jctc.2c00014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Peptide binding to membranes is common and fundamental in biochemistry and biophysics and critical for applications ranging from drug delivery to the treatment of bacterial infections. However, it is largely unclear, from a theoretical point of view, what peptides of different sequences and structures share in the membrane-binding and insertion process. In this work, we analyze three prototypical membrane-binding peptides (α-helical magainin, PGLa, and β-hairpin tachyplesin) during membrane binding, using molecular details provided by Markov state modeling and microsecond-long molecular dynamics simulations. By leveraging both geometric and data-driven collective variables that capture the essential physics of the amphiphilic and cationic peptide-membrane interactions, we reveal how the slowest kinetic process of membrane binding is the dynamic rolling of the peptide from an attached to a fully bound state. These results not only add fundamental knowledge of the theory of how peptides bind to biological membranes but also open new avenues to study general peptides in more complex environments for further applications.
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Affiliation(s)
- Jacob M Remington
- Department of Chemistry, The University of Vermont, Burlington, Vermont 05405, United States
| | - Jonathon B Ferrell
- Department of Chemistry, The University of Vermont, Burlington, Vermont 05405, United States
| | - Severin T Schneebeli
- Department of Chemistry, The University of Vermont, Burlington, Vermont 05405, United States
| | - Jianing Li
- Department of Chemistry, The University of Vermont, Burlington, Vermont 05405, United States
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3
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Zhang Z, Huang B, Zhang XC, Lin J. Cysteine-based crosslinking approach for characterization of oligomeric pore-forming proteins in the mitochondrial membranes. Methods Enzymol 2021; 649:371-396. [PMID: 33712193 DOI: 10.1016/bs.mie.2021.01.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Mitochondria are important not only to healthy but also dying cells. In particular, apoptotic cell death initiates when the mitochondrial outer membrane is permeabilized by Bax, a protein of the Bcl-2 family. Bax shares a structural fold with some α-helical bacterial pore-forming toxins before these proteins actively engage membranes. Despite decades of intensive research, the structures of the pores formed by these proteins are mostly unknown, mainly because the pores are assembled by different numbers of the proteins whose conformation and interaction are highly dynamic. Site-specific crosslinking of the pore-forming proteins in cellular membranes where the pores are assembled is a powerful approach to assess the biological pore structure, dynamics and function. In this chapter, we describe a cysteine-based site-specific crosslinking protocol for the Bax protein in the mitochondrial membrane. We discuss the expected results and the resulting structural-functional models for the pore-forming Bax oligomer, in comparison with other crosslinking approaches that have been used to study other mitochondrial protein complexes. At the end, we highlight the advantages of the crosslinking approaches as well as the limitations and alternative approaches.
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Affiliation(s)
- Zhi Zhang
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Bo Huang
- Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Xuejun C Zhang
- Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Jialing Lin
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States; Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.
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4
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A Structural Model for Bax∆2-Mediated Activation of Caspase 8-Dependent Apoptosis. Int J Mol Sci 2020; 21:ijms21155476. [PMID: 32751845 PMCID: PMC7432750 DOI: 10.3390/ijms21155476] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 07/26/2020] [Accepted: 07/29/2020] [Indexed: 01/28/2023] Open
Abstract
Bax∆2 is a pro-apoptotic anti-tumor protein in the Bax family. While most of the Bax family causes cell death by targeting mitochondria, Bax∆2 forms cytosolic aggregates and activates caspase 8-dependent cell death. We previously showed that the Bax∆2 helix α9 is critical for caspase 8 recruitment. However, the interaction between these two proteins at the structural level is unknown. In this in silico study, we performed molecular dynamics (MD) simulations and protein-protein docking on Bax∆2 variants. The results suggest that the Bax∆2 variants have different stable states. Mutating the Baxα mitochondria-targeting signal [L26P/L27P] appears to introduce a kink into helix α1. Protein-protein docking suggests that helices α9 of both wild-type Bax∆2 and Bax∆2 caspase 8 binding-deficient mutant [L164P] can fit in the same caspase 8 binding site, but the mutant is unable to fit as well as wild-type Bax∆2. Together, these data point to a structural basis for explaining Bax∆2 function in caspase 8-dependent cell death.
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5
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Nangia S, Boyd KJ, May ER. Molecular dynamics study of membrane permeabilization by wild-type and mutant lytic peptides from the non-enveloped Flock House virus. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1862:183102. [PMID: 31678020 DOI: 10.1016/j.bbamem.2019.183102] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 09/16/2019] [Accepted: 10/14/2019] [Indexed: 12/19/2022]
Abstract
Flock House virus (FHV) serves as a model system for understanding infection mechanisms utilized by non-enveloped viruses to transport across cellular membranes. During the infection cycle of FHV, a fundamental stage involves disruption of the endosomal membrane by membrane active peptides, following externalization of the peptides from the capsid interior. The FHV lytic agents are the 44 C-terminal amino acids residues of the capsid protein, which are auto-catalytically cleaved during the capsid maturation process. The cleaved peptides are termed γ peptides. In this study, we perform multi-scale molecular dynamics simulations including 40 μs all-atom molecular dynamics simulations to study the behavior of pre-inserted transmembrane lytic peptides at a high concentration in a neutral membrane. We study the dynamical organization among peptides to form oligomeric bundles in four systems including the wild-type γ peptide and three mutant forms; namely, a truncation mutant in which the 23 C-terminal residues are deleted (γ1), a construct where the 8 C-terminal residues of γ are fused to γ1 (Δ385-399 γ) and a single-point mutant (F402A γ), all of which have been experimentally shown to drastically affect infectivity and lytic activity compared to the wild-type γ. Our results shed light on the actions of varied forms of the FHV lytic peptide including membrane insertion, trans-membrane stability, peptide oligomerization, water permeation activity and dynamic pore formation. Findings from this study provide detailed structural information and rationale for the differences in lytic activity among variants of FHV γ.
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Affiliation(s)
- Shivangi Nangia
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269, United States of America
| | - Kevin J Boyd
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269, United States of America
| | - Eric R May
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269, United States of America.
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6
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健愉 冯, 玉山 朱, 陈 权, 凌 林, Jianyu F, Yushan Z, Quan C, Jialing L. [Physiological Function and Structural Basis of Bcl-2 Family Proteins]. ZHONGGUO XI BAO SHENG WU XUE XUE BAO 2019; 41:1477-1489. [PMID: 34249113 PMCID: PMC8265309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Apoptosis is an important biological process that plays a key role in the regulation of cell fate and homeostasis. The B-cell lymphoma-2 (Bcl-2) family proteins are important regulators of the apoptotic pathway, and their dysfunction is associated with a variety of diseases, including cancer, neurodegenerative and autoimmune diseases. In the past decade, a large number of research work on the physiological functions and atomic structures of Bcl-2 family proteins have been reported, which has deepened our understanding of the molecular mechanism and pathological significance of Bcl-2 family proteins. Recently, new drugs targeting different Bcl-2 proteins have been developed and used in clinics or tested in clinical trials. However, the complexity and diversity in functions and structures of Bcl-2 family have left many unsolved problems. This article summarizes current knowledge of the structure and function of Bcl-2 family proteins and discusses the pharmacological significance of Bcl-2 proteins as effective therapeutic targets.
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Affiliation(s)
| | | | | | - 林家 凌
- 俄克拉荷马大学健康科学中心生物化学与分子生物学系, 俄克拉何马城 73126-0901
| | - Feng Jianyu
- College of Life Sciences, Nankai University, Tianjin 300074, China
| | - Zhu Yushan
- College of Life Sciences, Nankai University, Tianjin 300074, China
| | - Chen Quan
- College of Life Sciences, Nankai University, Tianjin 300074, China
| | - Lin Jialing
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma 73126, USA
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7
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Abstract
The Bcl-2 family of proteins regulates mitochondrial outer membrane permeability thereby making life or death decisions for cells. Most of Bcl-2 proteins contain hydrophobic regions that are embedded in intracellular membranes such as mitochondria. These membrane proteins are difficult to express and purify thereby preluding biochemical and biophysical characterizations. Here, we describe a photocrosslinking approach based on in vitro synthesis of Bcl-2 proteins with photoreactive amino acid analogs incorporated at specific locations. These photoreactive proteins are reconstituted into liposomal membranes with defined phospholipids or mitochondrial membranes isolated from animals, and their interactions with other Bcl-2 proteins are detected by photocrosslinking.
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8
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Abstract
BCL-2 family proteins interact in a network that regulates apoptosis. The BH3 amino acid sequence motif serves to bind together this conglomerate protein family, both literally and figuratively. BH3 motifs are present in antiapoptotic and proapoptotic BCL-2 homologs, and in a separate group of unrelated BH3-only proteins often appended to the BCL-2 family. BH3-containing helices mediate many of their physical interactions to determine cell death versus survival, leading to the development of BH3 mimetics as therapeutics. Here we provide an overview of BCL-2 family interactions, their relevance in health and disease, and the progress toward regulating their interactions therapeutically.
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Affiliation(s)
- Jason D Huska
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA
| | - Heather M Lamb
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA
| | - J Marie Hardwick
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA.
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9
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Liao C, May V, Li J. Assessment of Conformational State Transitions of Class B GPCRs Using Molecular Dynamics. Methods Mol Biol 2019; 1947:3-19. [PMID: 30969408 DOI: 10.1007/978-1-4939-9121-1_1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Class B G protein-coupled receptors (GPCRs) comprise a family of 15 peptide-binding members, which are crucial targets for endocrine, metabolic, and stress-related disorders. While their protein structures and dynamics remain largely unclear, computer modeling and simulations represent a promising means to help solve such puzzles. Herein, we present a basic introduction to the methodology of molecular dynamics (MD) simulations and two analytical methods to assess the conformational ensembles and transitions of Class B GPCRs, using our recent studies of the human pituitary adenylate cyclase activating polypeptide (PAC1) receptor as an example. From long MD simulations, conformational ensembles with different roles in ligand binding and receptor activation are sampled to establish four states identified as either "open" or "closed" for the PAC1 receptor. Next, the dynamical network can be applied to analyze the simulations and identify key features within each conformational ensemble, which help distinguish the ligand-bound states of the PAC1 receptor from the ligand-free one. Further, the Markov State Model has emerged as a key approach to construct the transition network and connect the GPCR ensembles, providing detailed information for the transition pathways and kinetics. For the ligand-free PAC1 receptor, the transitions within the closed states are near 10-30 times faster than the open-closed transitions, which is likely related to the activation mechanism of the receptor. Overall, long MD simulations and analyses are useful to assess conformational transitions for the Class B GPCRs and to gain mechanistic insight, which is difficult to obtain using other methods.
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Affiliation(s)
- Chenyi Liao
- Department of Chemistry, The University of Vermont, Burlington, VT, USA
| | - Victor May
- Department of Neurological Sciences, Larner College of Medicine, The University of Vermont, Burlington, VT, USA
| | - Jianing Li
- Department of Chemistry, The University of Vermont, Burlington, VT, USA.
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10
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Chidchob P, Offenbartl-Stiegert D, McCarthy D, Luo X, Li J, Howorka S, Sleiman HF. Spatial Presentation of Cholesterol Units on a DNA Cube as a Determinant of Membrane Protein-Mimicking Functions. J Am Chem Soc 2018; 141:1100-1108. [DOI: 10.1021/jacs.8b11898] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Pongphak Chidchob
- Department of Chemistry, McGill University, Montreal, Quebec H3A 0B8, Canada
| | - Daniel Offenbartl-Stiegert
- Department of Chemistry, Institute of Structural Molecular Biology, University College London, London WC1H 0AJ, United Kingdom
| | - Dillon McCarthy
- Department of Chemistry, The University of Vermont, Burlington, Vermont 05405, United States
| | - Xin Luo
- Department of Chemistry, McGill University, Montreal, Quebec H3A 0B8, Canada
| | - Jianing Li
- Department of Chemistry, The University of Vermont, Burlington, Vermont 05405, United States
| | - Stefan Howorka
- Department of Chemistry, Institute of Structural Molecular Biology, University College London, London WC1H 0AJ, United Kingdom
| | - Hanadi F. Sleiman
- Department of Chemistry, McGill University, Montreal, Quebec H3A 0B8, Canada
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11
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Heppner DE, Dustin CM, Liao C, Hristova M, Veith C, Little AC, Ahlers BA, White SL, Deng B, Lam YW, Li J, van der Vliet A. Direct cysteine sulfenylation drives activation of the Src kinase. Nat Commun 2018; 9:4522. [PMID: 30375386 PMCID: PMC6207713 DOI: 10.1038/s41467-018-06790-1] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 09/19/2018] [Indexed: 01/17/2023] Open
Abstract
The Src kinase controls aspects of cell biology and its activity is regulated by intramolecular structural changes induced by protein interactions and tyrosine phosphorylation. Recent studies indicate that Src is additionally regulated by redox-dependent mechanisms, involving oxidative modification(s) of cysteines within the Src protein, although the nature and molecular-level impact of Src cysteine oxidation are unknown. Using a combination of biochemical and cell-based studies, we establish the critical importance of two Src cysteine residues, Cys-185 and Cys-277, as targets for H2O2-mediated sulfenylation (Cys-SOH) in redox-dependent kinase activation in response to NADPH oxidase-dependent signaling. Molecular dynamics and metadynamics simulations reveal the structural impact of sulfenylation of these cysteines, indicating that Cys-277-SOH enables solvent exposure of Tyr-416 to promote its (auto)phosphorylation, and that Cys-185-SOH destabilizes pTyr-527 binding to the SH2 domain. These redox-dependent Src activation mechanisms offer opportunities for development of Src-selective inhibitors in treatment of diseases where Src is aberrantly activated.
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Affiliation(s)
- David E Heppner
- Department of Pathology and Laboratory Medicine, Robert Larner, M.D. College of Medicine University of Vermont, 149 Beaumont Avenue, Burlington, VT, 05405, USA.
- Department of Cancer Biology, Dana-Farber Cancer Institute, 450 Brookline Ave, Boston, MA, 02215, USA.
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Ave, Boston, MA, 02115, USA.
| | - Christopher M Dustin
- Department of Pathology and Laboratory Medicine, Robert Larner, M.D. College of Medicine University of Vermont, 149 Beaumont Avenue, Burlington, VT, 05405, USA
| | - Chenyi Liao
- Department of Chemistry, College of Arts and Sciences, University of Vermont, 82 University Place, Burlington, VT, 05405, USA
| | - Milena Hristova
- Department of Pathology and Laboratory Medicine, Robert Larner, M.D. College of Medicine University of Vermont, 149 Beaumont Avenue, Burlington, VT, 05405, USA
| | - Carmen Veith
- Department of Pathology and Laboratory Medicine, Robert Larner, M.D. College of Medicine University of Vermont, 149 Beaumont Avenue, Burlington, VT, 05405, USA
| | - Andrew C Little
- Department of Pathology and Laboratory Medicine, Robert Larner, M.D. College of Medicine University of Vermont, 149 Beaumont Avenue, Burlington, VT, 05405, USA
| | - Bethany A Ahlers
- Department of Biology, College of Arts and Sciences, University of Vermont, 109 Carrigan Drive, Burlington, VT, 05405, USA
| | - Sheryl L White
- Department of Neurological Sciences, Robert Larner, M.D. College of Medicine University of Vermont, 149 Beaumont Avenue, Burlington, VT, 05405, USA
| | - Bin Deng
- Department of Biology, College of Arts and Sciences, University of Vermont, 109 Carrigan Drive, Burlington, VT, 05405, USA
| | - Ying-Wai Lam
- Department of Biology, College of Arts and Sciences, University of Vermont, 109 Carrigan Drive, Burlington, VT, 05405, USA
| | - Jianing Li
- Department of Chemistry, College of Arts and Sciences, University of Vermont, 82 University Place, Burlington, VT, 05405, USA.
| | - Albert van der Vliet
- Department of Pathology and Laboratory Medicine, Robert Larner, M.D. College of Medicine University of Vermont, 149 Beaumont Avenue, Burlington, VT, 05405, USA.
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12
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Liao C, Zhao X, Liu J, Schneebeli ST, Shelley JC, Li J. Capturing the multiscale dynamics of membrane protein complexes with all-atom, mixed-resolution, and coarse-grained models. Phys Chem Chem Phys 2018; 19:9181-9188. [PMID: 28317993 DOI: 10.1039/c7cp00200a] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The structures and dynamics of protein complexes are often challenging to model in heterogeneous environments such as biological membranes. Herein, we meet this fundamental challenge at attainable cost with all-atom, mixed-resolution, and coarse-grained models of vital membrane proteins. We systematically simulated five complex models formed by two distinct G protein-coupled receptors (GPCRs) in the lipid-bilayer membrane on the ns-to-μs timescales. These models, which suggest the swinging motion of an intracellular loop, for the first time, provide the molecular details for the regulatory role of such a loop. For the models at different resolutions, we observed consistent structural stability but various levels of speed-ups in protein dynamics. The mixed-resolution and coarse-grained models show two and four times faster protein diffusion than the all-atom models, in addition to a 4- and 400-fold speed-up in the simulation performance. Furthermore, by elucidating the strengths and challenges of combining all-atom models with reduced resolution models, this study can serve as a guide to simulating other complex systems in heterogeneous environments efficiently.
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Affiliation(s)
- Chenyi Liao
- Department of Chemistry, The University of Vermont, Burlington, VT 05405, USA.
| | - Xiaochuan Zhao
- Department of Chemistry, The University of Vermont, Burlington, VT 05405, USA.
| | - Jiyuan Liu
- Department of Chemistry, The University of Vermont, Burlington, VT 05405, USA.
| | | | - John C Shelley
- Schrödinger, Inc., 101 SW Main Street, Suite 1300, Portland, OR 97204, USA
| | - Jianing Li
- Department of Chemistry, The University of Vermont, Burlington, VT 05405, USA.
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13
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Liao C, Zhao X, Brewer M, May V, Li J. Conformational Transitions of the Pituitary Adenylate Cyclase-Activating Polypeptide Receptor, a Human Class B GPCR. Sci Rep 2017; 7:5427. [PMID: 28710390 PMCID: PMC5511175 DOI: 10.1038/s41598-017-05815-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 06/05/2017] [Indexed: 11/10/2022] Open
Abstract
The G protein-coupled pituitary adenylate cyclase-activating polypeptide receptor (PAC1R) is a potential therapeutic target for endocrine, metabolic and stress-related disorders. However, many questions regarding the protein structure and dynamics of PAC1R remain largely unanswered. Using microsecond-long simulations, we examined the open and closed PAC1R conformations interconnected within an ensemble of transitional states. The open-to-closed transition can be initiated by “unzipping” the extracellular domain and the transmembrane domain, mediated by a unique segment within the β3-β4 loop. Transitions between different conformational states range between microseconds to milliseconds, which clearly implicate allosteric effects propagating from the extracellular face of the receptor to the intracellular G protein-binding site. Such allosteric dynamics provides structural and mechanistic insights for the activation and modulation of PAC1R and related class B receptors.
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Affiliation(s)
- Chenyi Liao
- Department of Chemistry, University of Vermont, Burlington, VT, 05405, USA
| | - Xiaochuan Zhao
- Department of Chemistry, University of Vermont, Burlington, VT, 05405, USA
| | - Matthias Brewer
- Department of Chemistry, University of Vermont, Burlington, VT, 05405, USA
| | - Victor May
- Department of Neurological Sciences, College of Medicine, University of Vermont, Burlington, VT, 05405, USA
| | - Jianing Li
- Department of Chemistry, University of Vermont, Burlington, VT, 05405, USA.
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14
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Implementing WebGL and HTML5 in Macromolecular Visualization and Modern Computer-Aided Drug Design. Trends Biotechnol 2017; 35:559-571. [DOI: 10.1016/j.tibtech.2017.03.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 03/16/2017] [Accepted: 03/17/2017] [Indexed: 11/21/2022]
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15
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Aouacheria A, Baghdiguian S, Lamb HM, Huska JD, Pineda FJ, Hardwick JM. Connecting mitochondrial dynamics and life-or-death events via Bcl-2 family proteins. Neurochem Int 2017; 109:141-161. [PMID: 28461171 DOI: 10.1016/j.neuint.2017.04.009] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Accepted: 04/17/2017] [Indexed: 12/12/2022]
Abstract
The morphology of a population of mitochondria is the result of several interacting dynamical phenomena, including fission, fusion, movement, elimination and biogenesis. Each of these phenomena is controlled by underlying molecular machinery, and when defective can cause disease. New understanding of the relationships between form and function of mitochondria in health and disease is beginning to be unraveled on several fronts. Studies in mammals and model organisms have revealed that mitochondrial morphology, dynamics and function appear to be subject to regulation by the same proteins that regulate apoptotic cell death. One protein family that influences mitochondrial dynamics in both healthy and dying cells is the Bcl-2 protein family. Connecting mitochondrial dynamics with life-death pathway forks may arise from the intersection of Bcl-2 family proteins with the proteins and lipids that determine mitochondrial shape and function. Bcl-2 family proteins also have multifaceted influences on cells and mitochondria, including calcium handling, autophagy and energetics, as well as the subcellular localization of mitochondrial organelles to neuronal synapses. The remarkable range of physical or functional interactions by Bcl-2 family proteins is challenging to assimilate into a cohesive understanding. Most of their effects may be distinct from their direct roles in apoptotic cell death and are particularly apparent in the nervous system. Dual roles in mitochondrial dynamics and cell death extend beyond BCL-2 family proteins. In this review, we discuss many processes that govern mitochondrial structure and function in health and disease, and how Bcl-2 family proteins integrate into some of these processes.
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Affiliation(s)
- Abdel Aouacheria
- Institute of Evolutionary Sciences of Montpellier (ISEM), CNRS UMR 5554, University of Montpellier, Place Eugène Bataillon, 34095 Montpellier, France
| | - Stephen Baghdiguian
- Institute of Evolutionary Sciences of Montpellier (ISEM), CNRS UMR 5554, University of Montpellier, Place Eugène Bataillon, 34095 Montpellier, France
| | - Heather M Lamb
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, 615 North Wolfe St., Baltimore, MD 21205, USA
| | - Jason D Huska
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, 615 North Wolfe St., Baltimore, MD 21205, USA
| | - Fernando J Pineda
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, 615 North Wolfe St., Baltimore, MD 21205, USA; Department of Biostatistics, Johns Hopkins University, Bloomberg School of Public Health, 615 North Wolfe St., Baltimore, MD 21205, USA
| | - J Marie Hardwick
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, 615 North Wolfe St., Baltimore, MD 21205, USA.
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16
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A Small-Molecule Inhibitor of Bax and Bak Oligomerization Prevents Genotoxic Cell Death and Promotes Neuroprotection. Cell Chem Biol 2017; 24:493-506.e5. [PMID: 28392146 DOI: 10.1016/j.chembiol.2017.03.011] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Revised: 12/29/2016] [Accepted: 03/13/2017] [Indexed: 11/24/2022]
Abstract
Aberrant apoptosis can lead to acute or chronic degenerative diseases. Mitochondrial outer membrane permeabilization (MOMP) triggered by the oligomerization of the Bcl-2 family proteins Bax/Bak is an irreversible step leading to execution of apoptosis. Here, we describe the discovery of small-molecule inhibitors of Bax/Bak oligomerization that prevent MOMP. We demonstrate that these molecules disrupt multiple, but not all, interactions between Bax dimer interfaces thereby interfering with the formation of higher-order oligomers in the MOM, but not recruitment of Bax to the MOM. Small-molecule inhibition of Bax/Bak oligomerization allowed cells to evade apoptotic stimuli and rescued neurons from death after excitotoxicity, demonstrating that oligomerization of Bax is essential for MOMP. Our discovery of small-molecule Bax/Bak inhibitors provides novel tools for the investigation of the mechanisms leading to MOMP and will ultimately facilitate development of compounds inhibiting Bax/Bak in acute and chronic degenerative diseases.
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Oncogenic Mutations Differentially Affect Bax Monomer, Dimer, and Oligomeric Pore Formation in the Membrane. Sci Rep 2016; 6:33340. [PMID: 27630059 PMCID: PMC5024136 DOI: 10.1038/srep33340] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 08/25/2016] [Indexed: 12/20/2022] Open
Abstract
Dysfunction of Bax, a pro-apoptotic regulator of cellular metabolism is implicated in neurodegenerative diseases and cancer. We have constructed the first atomistic models of the Bax oligomeric pore consisting with experimental residue-residue distances. The models are stable, capturing well double electron-electron resonance (DEER) spectroscopy measurements and provide structural details in line with the DEER data. Comparison with the latest experimental results revealed that our models agree well with both Bax and Bak pores, pointed to a converged structural arrangement for Bax and Bak pore formation. Using multi-scale molecular dynamics simulations, we probed mutational effects on Bax transformation from monomer → dimer → membrane pore formation at atomic resolution. We observe that two cancer-related mutations, G40E and S118I, allosterically destabilize the monomer and stabilize an off-pathway swapped dimer, preventing productive pore formation. This observation suggests a mechanism whereby the mutations may work mainly by over-stabilizing the monomer → dimer transformation toward an unproductive off-pathway swapped-dimer state. Our observations point to misfolded Bax states, shedding light on the molecular mechanism of Bax mutation-elicited cancer. Most importantly, the structure of the Bax pore facilitates future study of releases cytochrome C in atomic detail.
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