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Saccuzzo EG, Mebrat MD, Scelsi HF, Kim M, Ma MT, Su X, Hill SE, Rheaume E, Li R, Torres MP, Gumbart JC, Van Horn WD, Lieberman RL. Competition between inside-out unfolding and pathogenic aggregation in an amyloid-forming β-propeller. Nat Commun 2024; 15:155. [PMID: 38168102 PMCID: PMC10762032 DOI: 10.1038/s41467-023-44479-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 12/14/2023] [Indexed: 01/05/2024] Open
Abstract
Studies of folded-to-misfolded transitions using model protein systems reveal a range of unfolding needed for exposure of amyloid-prone regions for subsequent fibrillization. Here, we probe the relationship between unfolding and aggregation for glaucoma-associated myocilin. Mutations within the olfactomedin domain of myocilin (OLF) cause a gain-of-function, namely cytotoxic intracellular aggregation, which hastens disease progression. Aggregation by wild-type OLF (OLFWT) competes with its chemical unfolding, but only below the threshold where OLF loses tertiary structure. Representative moderate (OLFD380A) and severe (OLFI499F) disease variants aggregate differently, with rates comparable to OLFWT in initial stages of unfolding, and variants adopt distinct partially folded structures seen along the OLFWT urea-unfolding pathway. Whether initiated with mutation or chemical perturbation, unfolding propagates outward to the propeller surface. In sum, for this large protein prone to amyloid formation, the requirement for a conformational change to promote amyloid fibrillization leads to direct competition between unfolding and aggregation.
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Affiliation(s)
- Emily G Saccuzzo
- School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, USA
| | - Mubark D Mebrat
- Biodesign Center for Personalized Diagnostics, Arizona State University, Tempe, USA
- School of Molecular Sciences, Arizona State University, Tempe, USA
| | - Hailee F Scelsi
- School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, USA
| | - Minjoo Kim
- Biodesign Center for Personalized Diagnostics, Arizona State University, Tempe, USA
- School of Molecular Sciences, Arizona State University, Tempe, USA
| | - Minh Thu Ma
- School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, USA
| | - Xinya Su
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, USA
| | - Shannon E Hill
- School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, USA
| | - Elisa Rheaume
- Interdisciplinary Graduate Program in Quantitative Biosciences, Georgia Institute of Technology, Atlanta, USA
| | - Renhao Li
- Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta and Department of Pediatrics, Emory University School of Medicine, Atlanta, USA
| | - Matthew P Torres
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, USA
| | - James C Gumbart
- School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, USA
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, USA
- School of Physics, Georgia Institute of Technology, Atlanta, USA
| | - Wade D Van Horn
- Biodesign Center for Personalized Diagnostics, Arizona State University, Tempe, USA.
- School of Molecular Sciences, Arizona State University, Tempe, USA.
| | - Raquel L Lieberman
- School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, USA.
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2
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Esquivel AR, Hill SE, Blair LJ. DnaJs are enriched in tau regulators. Int J Biol Macromol 2023; 253:127486. [PMID: 37852393 PMCID: PMC10842427 DOI: 10.1016/j.ijbiomac.2023.127486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 10/09/2023] [Accepted: 10/15/2023] [Indexed: 10/20/2023]
Abstract
The aberrant accumulation of tau protein is implicated as a pathogenic factor in many neurodegenerative diseases. Tau seeding may underlie its predictable spread in these diseases. Molecular chaperones can modulate tau pathology, but their effects have mainly been studied in isolation. This study employed a semi-high throughput assay to identify molecular chaperones influencing tau seeding using Tau RD P301S FRET Biosensor cells, which express a portion of tau containing the frontotemporal dementia-related P301S tau mutation fused to a FRET biosensor. Approximately fifty chaperones from five major families were screened using live cell imaging to monitor FRET-positive tau seeding. Among the tested chaperones, five exhibited significant effects on tau in the primary screen. Notably, three of these were from the DnaJ family. In subsequent studies, overexpression of DnaJA2, DnaJB1, and DnaJB6b resulted in significant reductions in tau levels. Knockdown experiments by shRNA revealed an inverse correlation between DnaJB1 and DnaJB6b with tau levels. DnaJB6b overexpression, specifically, reduced total tau levels in a cellular model with a pre-existing pool of tau, partially through enhanced proteasomal degradation. Further, DnaJB6b interacted with tau complexes. These findings highlight the potent chaperone activity within the DnaJ family, particularly DnaJB6b, towards tau.
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Affiliation(s)
- Abigail R Esquivel
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA; USF Health Byrd Alzheimer's Institute, University of South Florida, Tampa, FL 33613, USA
| | - Shannon E Hill
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA; USF Health Byrd Alzheimer's Institute, University of South Florida, Tampa, FL 33613, USA
| | - Laura J Blair
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA; USF Health Byrd Alzheimer's Institute, University of South Florida, Tampa, FL 33613, USA; Research Service, James A Haley Veterans Hospital, 13000 Bruce B Downs Blvd, Tampa, FL 33612, USA.
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3
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Hill SE, Beaulieu-Abdelahad D, Lemus A, Webster JM, Ospina SR, Darling AL, Martin MD, Patel S, Bridenstine L, Swonger R, Paul S, Blackburn R, Calcul L, Dickey CA, Leahy JW, Blair LJ. Benzothiazole Substitution Analogs of Rhodacyanine Hsp70 Inhibitors Modulate Tau Accumulation. ACS Chem Biol 2023; 18:1124-1135. [PMID: 37144894 PMCID: PMC10443619 DOI: 10.1021/acschembio.2c00919] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The accumulation and aggregation of the microtubule-associated protein tau (tau) into intracellular neuronal tangles are a hallmark of a range of progressive neurodegenerative tauopathies, including Alzheimer's disease (AD), frontotemporal dementia, Pick's disease, and progressive supranuclear palsy. The aberrant phosphorylation of tau is associated with tau aggregates in AD. Members of the heat shock protein 70 kDa (Hsp70) family of chaperones bind directly to tau and modulate tau clearance and aggregation. Small molecules that inhibit the Hsp70 family of chaperones have been shown to reduce the accumulation of tau, including phosphorylated tau. Here, eight analogs of the rhodacyanine inhibitor, JG-98, were synthesized and evaluated. Like JG-98, many of the compounds inhibited ATPase activity of the cytosolic heat shock cognate 70 protein (Hsc70) and reduced total, aggregated, and phosphorylated tau accumulation in cultured cells. Three compounds, representing divergent clogP values, were evaluated for in vivo blood-brain barrier penetration and tau reduction in an ex vivo brain slice model. AL69, the compound with the lowest clogP and the lowest membrane retention in a parallel artificial membrane permeability assay (PAMPA), reduced phosphorylated tau accumulation. Our results suggest that benzothiazole substitutions of JG-98 that increase hydrophilicity may increase the efficacy of these Hsp70 inhibitors to reduce phosphorylated tau.
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Affiliation(s)
- Shannon E. Hill
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA
- USF Health Byrd Alzheimer’s Institute, University of South Florida, Tampa, FL 33612, USA
| | - David Beaulieu-Abdelahad
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA
- USF Health Byrd Alzheimer’s Institute, University of South Florida, Tampa, FL 33612, USA
| | - Andrea Lemus
- Department of Chemistry, University of South Florida, 4202 East Fowler Avenue, CHE 205, Tampa, Florida 33620, USA
| | - Jack M. Webster
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA
- USF Health Byrd Alzheimer’s Institute, University of South Florida, Tampa, FL 33612, USA
| | - Santiago Rodriguez Ospina
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA
- USF Health Byrd Alzheimer’s Institute, University of South Florida, Tampa, FL 33612, USA
| | - April L. Darling
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA
- USF Health Byrd Alzheimer’s Institute, University of South Florida, Tampa, FL 33612, USA
| | - Mackenzie D. Martin
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA
- USF Health Byrd Alzheimer’s Institute, University of South Florida, Tampa, FL 33612, USA
| | - Shreya Patel
- Department of Chemistry, University of South Florida, 4202 East Fowler Avenue, CHE 205, Tampa, Florida 33620, USA
| | - Liznair Bridenstine
- Department of Chemistry, University of South Florida, 4202 East Fowler Avenue, CHE 205, Tampa, Florida 33620, USA
| | - Ronald Swonger
- Department of Chemistry, University of South Florida, 4202 East Fowler Avenue, CHE 205, Tampa, Florida 33620, USA
| | - Steven Paul
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA
- USF Health Byrd Alzheimer’s Institute, University of South Florida, Tampa, FL 33612, USA
| | - Roy Blackburn
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA
- USF Health Byrd Alzheimer’s Institute, University of South Florida, Tampa, FL 33612, USA
| | - Laurent Calcul
- Department of Chemistry, University of South Florida, 4202 East Fowler Avenue, CHE 205, Tampa, Florida 33620, USA
| | - Chad A. Dickey
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA
- USF Health Byrd Alzheimer’s Institute, University of South Florida, Tampa, FL 33612, USA
- Research Service, James A Haley Veterans Hospital, 13000 Bruce B Downs Blvd, Tampa, FL 33612, USA
| | - James W. Leahy
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA
- Department of Chemistry, University of South Florida, 4202 East Fowler Avenue, CHE 205, Tampa, Florida 33620, USA
- Center for Drug Discovery and Innovation, University of South Florida, 3720 Spectrum Boulevard, Suite 303, Tampa, Florida 33612, USA
| | - Laura J. Blair
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA
- USF Health Byrd Alzheimer’s Institute, University of South Florida, Tampa, FL 33612, USA
- Research Service, James A Haley Veterans Hospital, 13000 Bruce B Downs Blvd, Tampa, FL 33612, USA
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Gebru NT, Hill SE, Blair LJ. Genetically engineered mouse models of FK506-binding protein 5. J Cell Biochem 2023:10.1002/jcb.30374. [PMID: 36780339 PMCID: PMC10423308 DOI: 10.1002/jcb.30374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 11/25/2022] [Accepted: 01/15/2023] [Indexed: 02/14/2023]
Abstract
FK506 binding protein 51 (FKBP51) is a molecular chaperone that influences stress response. In addition to having an integral role in the regulation of steroid hormone receptors, including glucocorticoid receptor, FKBP51 has been linked with several biological processes including metabolism and neuronal health. Genetic and epigenetic alterations in the gene that encodes FKBP51, FKBP5, are associated with increased susceptibility to multiple neuropsychiatric disorders, which has fueled much of the research on this protein. Because of the complexity of these processes, animal models have been important in understanding the role of FKBP51. This review examines each of the current mouse models of FKBP5, which include whole animal knockout, conditional knockout, overexpression, and humanized mouse models. The generation of each model and observational details are discussed, including behavioral phenotypes, molecular changes, and electrophysiological alterations basally and following various challenges. While much has been learned through these models, there are still many aspects of FKBP51 biology that remain opaque and future studies are needed to help illuminate these current gaps in knowledge. Overall, FKBP5 continues to be an exciting potential target for stress-related disorders.
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Affiliation(s)
- Niat T. Gebru
- USF Health Byrd Alzheimer’s Institute, University of South Florida, 4001 E. Fletcher Ave. Tampa, Florida 33613, United States
- Department of Molecular Medicine, University of South Florida, 4001 E. Fletcher Ave. Tampa, Florida 33613, United States
| | - Shannon E. Hill
- USF Health Byrd Alzheimer’s Institute, University of South Florida, 4001 E. Fletcher Ave. Tampa, Florida 33613, United States
- Department of Molecular Medicine, University of South Florida, 4001 E. Fletcher Ave. Tampa, Florida 33613, United States
| | - Laura J. Blair
- USF Health Byrd Alzheimer’s Institute, University of South Florida, 4001 E. Fletcher Ave. Tampa, Florida 33613, United States
- Department of Molecular Medicine, University of South Florida, 4001 E. Fletcher Ave. Tampa, Florida 33613, United States
- Research Service, James A. Haley Veterans Hospital, 13000 Bruce B Downs Blvd, Tampa, FL 33612, United States
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5
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Jiang L, Chakraborty P, Zhang L, Wong M, Hill SE, Webber CJ, Libera J, Blair LJ, Wolozin B, Zweckstetter M. Chaperoning of specific tau structure by immunophilin FKBP12 regulates the neuronal resilience to extracellular stress. Sci Adv 2023; 9:eadd9789. [PMID: 36724228 PMCID: PMC9891691 DOI: 10.1126/sciadv.add9789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 01/05/2023] [Indexed: 06/18/2023]
Abstract
Alzheimer's disease and related tauopathies are characterized by the pathogenic misfolding and aggregation of the microtubule-associated protein tau. Understanding how endogenous chaperones modulate tau misfolding could guide future therapies. Here, we show that the immunophilin FKBP12, the 12-kDa FK506-binding protein (also known as FKBP prolyl isomerase 1A), regulates the neuronal resilience by chaperoning a specific structure in monomeric tau. Using a combination of mouse and cell experiments, in vitro aggregation experiments, nuclear magnetic resonance-based structural analysis of monomeric tau, site-specific phosphorylation and mutation, as well as structure-based analysis using the neural network-based structure prediction program AlphaFold, we define the molecular factors that govern the binding of FKBP12 to tau and its influence on tau-induced neurotoxicity. We further demonstrate that tyrosine phosphorylation of tau blocks the binding of FKBP12 to two highly specific structural motifs in tau. Our data together with previous results demonstrating FKBP12/tau colocalization in neurons and neurofibrillary tangles support a critical role of FKBP12 in regulating tau pathology.
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Affiliation(s)
- Lulu Jiang
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA 02118, USA
| | - Pijush Chakraborty
- German Center for Neurodegenerative Diseases (DZNE), Von-Siebold-Str. 3a, 37075 Göttingen, Germany
| | - Lushuang Zhang
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA 02118, USA
| | - Melissa Wong
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA 02118, USA
| | - Shannon E. Hill
- Department of Molecular Medicine, College of Medicine, Byrd Alzheimer’s Institute, University of South Florida, Tampa, FL 33612, USA
| | - Chelsea Joy Webber
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA 02118, USA
| | - Jenna Libera
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA 02118, USA
| | - Laura J. Blair
- Department of Molecular Medicine, College of Medicine, Byrd Alzheimer’s Institute, University of South Florida, Tampa, FL 33612, USA
| | - Benjamin Wolozin
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA 02118, USA
- Center for Neurophotonics, Boston University, Boston, MA 02215, USA
- Center for Systems Neuroscience, Boston University, Boston, MA 02215, USA
| | - Markus Zweckstetter
- German Center for Neurodegenerative Diseases (DZNE), Von-Siebold-Str. 3a, 37075 Göttingen, Germany
- Department for NMR-based Structural Biology, Max Planck Institute for Multidisciplinary Sciences, Am Faßberg 11, 37077 Göttingen, Germany
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6
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Patel RS, Lui A, Hudson C, Moss L, Sparks RP, Hill SE, Shi Y, Cai J, Blair LJ, Bickford PC, Patel NA. Small molecule targeting long noncoding RNA GAS5 administered intranasally improves neuronal insulin signaling and decreases neuroinflammation in an aged mouse model. Sci Rep 2023; 13:317. [PMID: 36609440 PMCID: PMC9822944 DOI: 10.1038/s41598-022-27126-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Accepted: 12/26/2022] [Indexed: 01/09/2023] Open
Abstract
Shifts in normal aging set stage for neurodegeneration and dementia affecting 1 in 10 adults. The study demonstrates that lncRNA GAS5 is decreased in aged and Alzheimer's disease brain. The role and targets of lncRNA GAS5 in the aging brain were elucidated using a GAS5-targeting small molecule NPC86, a frontier in lncRNA-targeting therapeutic. Robust techniques such as molecular dynamics simulation of NPC86 binding to GAS5, in vitro functional assays demonstrating that GAS5 regulates insulin signaling, neuronal survival, phosphorylation of tau, and neuroinflammation via toll-like receptors support the role of GAS5 in maintaining healthy neurons. The study demonstrates the safety and efficacy of intranasal NPC86 treatment in aged mice to improve cellular functions with transcriptomic analysis in response to NPC86. In summary, the study demonstrates that GAS5 contributes to pathways associated with neurodegeneration and NPC86 has tremendous therapeutic potential to prevent the advent of neurodegenerative diseases and dementias.
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Affiliation(s)
- Rekha S. Patel
- grid.281075.90000 0001 0624 9286James A. Haley Veterans Hospital, Research Service, 13000 Bruce B. Downs Blvd., Tampa, FL 33612 USA
| | - Ashley Lui
- grid.170693.a0000 0001 2353 285XDepartment of Molecular Medicine, University of South Florida, Tampa, FL 33612 USA
| | - Charles Hudson
- grid.281075.90000 0001 0624 9286James A. Haley Veterans Hospital, Research Service, 13000 Bruce B. Downs Blvd., Tampa, FL 33612 USA
| | - Lauren Moss
- grid.170693.a0000 0001 2353 285XDepartment of Neurosurgery and Brain Repair, University of South Florida, Tampa, FL 33612 USA
| | - Robert P. Sparks
- Present Address: UMass Chan Medical School, Worcester, MA 01655 USA
| | - Shannon E. Hill
- grid.170693.a0000 0001 2353 285XDepartment of Molecular Medicine, University of South Florida, Tampa, FL 33612 USA ,grid.170693.a0000 0001 2353 285XUSF Health Byrd Institute, University of South Florida, Tampa, FL 33612 USA
| | - Yan Shi
- grid.170693.a0000 0001 2353 285XDepartment of Chemistry, University of South Florida, Tampa, FL 33612 USA
| | - Jianfeng Cai
- grid.170693.a0000 0001 2353 285XDepartment of Chemistry, University of South Florida, Tampa, FL 33612 USA
| | - Laura J. Blair
- grid.281075.90000 0001 0624 9286James A. Haley Veterans Hospital, Research Service, 13000 Bruce B. Downs Blvd., Tampa, FL 33612 USA ,grid.170693.a0000 0001 2353 285XDepartment of Molecular Medicine, University of South Florida, Tampa, FL 33612 USA ,grid.170693.a0000 0001 2353 285XUSF Health Byrd Institute, University of South Florida, Tampa, FL 33612 USA
| | - Paula C. Bickford
- grid.281075.90000 0001 0624 9286James A. Haley Veterans Hospital, Research Service, 13000 Bruce B. Downs Blvd., Tampa, FL 33612 USA ,grid.170693.a0000 0001 2353 285XDepartment of Neurosurgery and Brain Repair, University of South Florida, Tampa, FL 33612 USA
| | - Niketa A. Patel
- grid.281075.90000 0001 0624 9286James A. Haley Veterans Hospital, Research Service, 13000 Bruce B. Downs Blvd., Tampa, FL 33612 USA ,grid.170693.a0000 0001 2353 285XDepartment of Molecular Medicine, University of South Florida, Tampa, FL 33612 USA
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7
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Hill SE, Esquivel AR, Ospina SR, Rahal LM, Dickey CA, Blair LJ. Chaperoning activity of the cyclophilin family prevents tau aggregation. Protein Sci 2022; 31:e4448. [PMID: 36305768 PMCID: PMC9597375 DOI: 10.1002/pro.4448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 08/18/2022] [Accepted: 09/11/2022] [Indexed: 11/09/2022]
Abstract
Tauopathies, such as Alzheimer's disease, are characterized by the misfolding and progressive accumulation of the microtubule associated protein tau. Chaperones, tasked with maintaining protein homeostasis, can become imbalanced with age and contribute to the progression of neurodegenerative disease. Cyclophilins are a promising pool of underinvestigated chaperones with peptidyl-prolyl isomerase activity that may play protective roles in regulating tau aggregation. Using a Thioflavin T fluorescence-based assay to monitor in vitro tau aggregation, all eight cyclophilins, which include PPIA to PPIH prevent tau aggregation, with PPIB, PPIC, PPID, and PPIH showing the greatest inhibition. The low thermal stability of PPID and the strong heparin binding of PPIB undermines the simplistic interpretation of reduced tau aggregation. In a cellular model of tau accumulation, all cyclophilins, except PPID and PPIH, reduce insoluble tau. PPIB, PPIC, PPIE, and PPIF also reduce soluble tau levels with PPIC exclusively protecting cells from tau seeding. Overall, this study demonstrates cyclophilins prevent tau fibril formation and many reduce cellular insoluble tau accumulation with PPIC having the greatest potential as a molecular tool to mitigate tau seeding and accumulation.
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Affiliation(s)
- Shannon E. Hill
- USF Health Byrd Alzheimer's InstituteUniversity of South FloridaTampaFloridaUSA
- Department of Molecular MedicineUniversity of South FloridaTampaFloridaUSA
| | - Abigail R. Esquivel
- USF Health Byrd Alzheimer's InstituteUniversity of South FloridaTampaFloridaUSA
- Department of Molecular MedicineUniversity of South FloridaTampaFloridaUSA
| | - Santiago Rodriguez Ospina
- USF Health Byrd Alzheimer's InstituteUniversity of South FloridaTampaFloridaUSA
- Department of Molecular MedicineUniversity of South FloridaTampaFloridaUSA
| | - Lauren M. Rahal
- USF Health Byrd Alzheimer's InstituteUniversity of South FloridaTampaFloridaUSA
- Department of Molecular MedicineUniversity of South FloridaTampaFloridaUSA
| | - Chad A. Dickey
- USF Health Byrd Alzheimer's InstituteUniversity of South FloridaTampaFloridaUSA
- Department of Molecular MedicineUniversity of South FloridaTampaFloridaUSA
| | - Laura J. Blair
- USF Health Byrd Alzheimer's InstituteUniversity of South FloridaTampaFloridaUSA
- Department of Molecular MedicineUniversity of South FloridaTampaFloridaUSA
- Research ServiceJames A. Haley Veterans HospitalTampaFloridaUSA
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8
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Smith KE, Macintyre AK, Weakley S, Hill SE, Escobar O, Fergie G. Public understandings of potential policy responses to health inequalities: Evidence from a UK national survey and citizens' juries in three UK cities. Soc Sci Med 2021; 291:114458. [PMID: 34655938 PMCID: PMC8711040 DOI: 10.1016/j.socscimed.2021.114458] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 10/02/2021] [Accepted: 10/04/2021] [Indexed: 11/29/2022]
Abstract
A substantial body of research describes the distribution, causes and potential reduction of health inequalities, yet little scholarship examines public understandings of these inequalities. Existing work is dominated by small-scale, qualitative studies of the experiences of specific communities. As a result, we know very little about what broader publics think about health inequalities; and even less about public views of potential policy responses. This is an important gap since previous research shows many researchers and policymakers believe proposals for 'upstream' policies are unlikely to attract sufficient public support to be viable. This mixed methods study combined a nationally representative survey with three two-day citizens' juries exploring public views of health inequalities and potential policy responses in three UK cities (Glasgow, Manchester and Liverpool) in July 2016. Comparing public opinion elicited via a survey to public reasoning generated through deliberative processes offers insight into the formation of public views. The results challenge perceptions that there is a lack of public support for upstream, macro-level policy proposals and instead demonstrate support for proposals aiming to tackle health inequalities via improvements to living and working conditions, with more limited support for proposals targeting individual behavioural change. At the same time, some macro-economic proposals, notably those involving tax increases, proved controversial among study participants and results varied markedly by data source. Our analysis suggests that this results from three intersecting factors: a resistance to ideas viewed as disempowering (which include, fundamentally, the idea that health inequalities exist); the prevalence of individualising and fatalistic discourses, which inform resistance to diverse policy proposals (but especially those that are more 'upstream', macro-level proposals); and a lack of trust in (local and national) government. This suggests that efforts to enhance public support for evidence-informed policy responses to health inequalities may struggle unless these broader challenges are also addressed.
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Affiliation(s)
- K E Smith
- School of Social Work & Social Policy, University of Strathclyde, Lord Hope Building, 141 St James Road, Glasgow, G4 0LT, UK; School of Social & Political Science, University of Edinburgh, Chrystal Macmillan Building, 15a George Square, Edinburgh, EH8 9LD, UK.
| | - A K Macintyre
- School of Social Work & Social Policy, University of Strathclyde, Lord Hope Building, 141 St James Road, Glasgow, G4 0LT, UK.
| | - S Weakley
- Policy Scotland, University of Glasgow, Adam Smith Building, 40 Bute Gardens, Glasgow, G12 8RT, UK.
| | - S E Hill
- School of Social & Political Science, University of Edinburgh, Chrystal Macmillan Building, 15a George Square, Edinburgh, EH8 9LD, UK.
| | - O Escobar
- School of Social & Political Science, University of Edinburgh, Chrystal Macmillan Building, 15a George Square, Edinburgh, EH8 9LD, UK.
| | - G Fergie
- MRC/CSO Social and Public Health Sciences Unit, University of Glasgow, Berkeley Square, 99 Berkeley Street, Glasgow, G3 7HR, UK.
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9
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Crisan CV, Chandrashekar H, Everly C, Steinbach G, Hill SE, Yunker PJ, Lieberman RR, Hammer BK. A New Contact Killing Toxin Permeabilizes Cells and Belongs to a Broadly Distributed Protein Family. mSphere 2021; 6:e0031821. [PMID: 34287011 PMCID: PMC8386463 DOI: 10.1128/msphere.00318-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 06/21/2021] [Indexed: 01/12/2023] Open
Abstract
Vibrio cholerae is an aquatic Gram-negative bacterium that causes severe diarrheal cholera disease when ingested by humans. To eliminate competitor cells in both the external environment and inside hosts, V. cholerae uses the type VI secretion system (T6SS). The T6SS is a macromolecular contact-dependent weapon employed by many Gram-negative bacteria to deliver cytotoxic proteins into adjacent cells. In addition to canonical T6SS gene clusters encoded by all sequenced V. cholerae isolates, strain BGT49 encodes another locus, which we named auxiliary (Aux) cluster 4. The Aux 4 cluster is located on a mobile genetic element and can be used by killer cells to eliminate both V. cholerae and Escherichia coli cells in a T6SS-dependent manner. A putative toxin encoded in the cluster, which we name TpeV (type VI permeabilizing effector Vibrio), shares no homology to known proteins and does not contain motifs or domains indicative of function. Ectopic expression of TpeV in the periplasm of E. coli permeabilizes cells and disrupts the membrane potential. Using confocal microscopy, we confirm that susceptible target cells become permeabilized when competed with killer cells harboring the Aux 4 cluster. We also determine that tpiV, the gene located immediately downstream of tpeV, encodes an immunity protein that neutralizes the toxicity of TpeV. Finally, we show that TpeV homologs are broadly distributed across important human, animal, and plant pathogens and are localized in proximity to other T6SS genes. Our results suggest that TpeV is a toxin that belongs to a large family of T6SS proteins. IMPORTANCE Bacteria live in polymicrobial communities where competition for resources and space is essential for survival. Proteobacteria use the T6SS to eliminate neighboring cells and cause disease. However, the mechanisms by which many T6SS toxins kill or inhibit susceptible target cells are poorly understood. The sequence of the TpeV toxin that we describe here is unlike any previously described protein. We demonstrate that it has antimicrobial activity by permeabilizing cells, eliminating membrane potentials, and causing severe cytotoxicity. TpeV homologs are found near known T6SS genes in human, animal, and plant bacterial pathogens, indicating that the toxin is a representative member of a broadly distributed protein family. We propose that TpeV-like toxins contribute to the fitness of many bacteria. Finally, since antibiotic resistance is a critical global health threat, the discovery of new antimicrobial mechanisms could lead to the development of new treatments against resistant strains.
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Affiliation(s)
- Cristian V. Crisan
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
- Parker H. Petit Institute for Bioengineering & Bioscience, Georgia Institute of Technology, Atlanta, Georgia, USA
- Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Harshini Chandrashekar
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Catherine Everly
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
- Parker H. Petit Institute for Bioengineering & Bioscience, Georgia Institute of Technology, Atlanta, Georgia, USA
- Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Gabi Steinbach
- Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, Georgia, USA
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Shannon E. Hill
- Parker H. Petit Institute for Bioengineering & Bioscience, Georgia Institute of Technology, Atlanta, Georgia, USA
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Peter J. Yunker
- Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, Georgia, USA
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Raquel R. Lieberman
- Parker H. Petit Institute for Bioengineering & Bioscience, Georgia Institute of Technology, Atlanta, Georgia, USA
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Brian K. Hammer
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
- Parker H. Petit Institute for Bioengineering & Bioscience, Georgia Institute of Technology, Atlanta, Georgia, USA
- Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, Georgia, USA
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10
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Patterson-Orazem AC, Qerqez AN, Azouz LR, Ma MT, Hill SE, Ku Y, Schildmeyer LA, Maynard JA, Lieberman RL. Recombinant antibodies recognize conformation-dependent epitopes of the leucine zipper of misfolding-prone myocilin. J Biol Chem 2021; 297:101067. [PMID: 34384785 PMCID: PMC8408531 DOI: 10.1016/j.jbc.2021.101067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 08/02/2021] [Accepted: 08/06/2021] [Indexed: 11/11/2022] Open
Abstract
Recombinant antibodies with well-characterized epitopes and known conformational specificities are critical reagents to support robust interpretation and reproducibility of immunoassays across biomedical research. For myocilin, a protein prone to misfolding that is associated with glaucoma and an emerging player in other human diseases, currently available antibodies are unable to differentiate among the numerous disease-associated protein states. This fundamentally constrains efforts to understand the connection between myocilin structure, function, and disease. To address this concern, we used protein engineering methods to develop new recombinant antibodies that detect the N-terminal leucine zipper structural domain of myocilin and that are cross-reactive for human and mouse myocilin. After harvesting spleens from immunized mice and in vitro library panning, we identified two antibodies, 2A4 and 1G12. 2A4 specifically recognizes a folded epitope while 1G12 recognizes a range of conformations. We matured antibody 2A4 for improved biophysical properties, resulting in variant 2H2. In a human IgG1 format, 2A4, 1G12, and 2H2 immunoprecipitate full-length folded myocilin present in the spent media of human trabecular meshwork (TM) cells, and 2H2 can visualize myocilin in fixed human TM cells using fluorescence microscopy. These new antibodies should find broad application in glaucoma and other research across multiple species platforms.
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Affiliation(s)
| | - Ahlam N Qerqez
- Department of Chemical Engineering, University of Texas at Austin, Austin, Texas, USA
| | - Laura R Azouz
- Department of Chemical Engineering, University of Texas at Austin, Austin, Texas, USA
| | - Minh Thu Ma
- School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Shannon E Hill
- School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Yemo Ku
- School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Lisa A Schildmeyer
- School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Jennifer A Maynard
- Department of Chemical Engineering, University of Texas at Austin, Austin, Texas, USA; Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas, USA.
| | - Raquel L Lieberman
- School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, USA.
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11
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Peng B, Dikdan R, Hill SE, Patterson-Orazem AC, Lieberman RL, Fahrni CJ, Dickson RM. Optically Modulated and Optically Activated Delayed Fluorescent Proteins through Dark State Engineering. J Phys Chem B 2021; 125:5200-5209. [PMID: 33978414 DOI: 10.1021/acs.jpcb.1c00649] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Modulating fluorescent protein emission holds great potential for increasing readout sensitivity for applications in biological imaging and detection. Here, we identify and engineer optically modulated yellow fluorescent proteins (EYFP, originally 10C, but renamed EYFP later, and mVenus) to yield new emitters with distinct modulation profiles and unique, optically gated, delayed fluorescence. The parent YFPs are individually modulatable through secondary illumination, depopulating a long-lived dark state to dynamically increase fluorescence. A single point mutation introduced near the chromophore in each of these YFPs provides access to a second, even longer-lived modulatable dark state, while a different double mutant renders EYFP unmodulatable. The naturally occurring dark state in the parent YFPs yields strong fluorescence modulation upon long-wavelength-induced dark state depopulation, allowing selective detection at the frequency at which the long wavelength secondary laser is intensity modulated. Distinct from photoswitches, however, this near IR secondary coexcitation repumps the emissive S1 level from the long-lived triplet state, resulting in optically activated delayed fluorescence (OADF). This OADF results from secondary laser-induced, reverse intersystem crossing (RISC), producing additional nanosecond-lived, visible fluorescence that is delayed by many microseconds after the primary excitation has turned off. Mutation of the parent chromophore environment opens an additional modulation pathway that avoids the OADF-producing triplet state, resulting in a second, much longer-lived, modulatable dark state. These Optically Modulated and Optically Activated Delayed Fluorescent Proteins (OMFPs and OADFPs) are thus excellent for background- and reference-free, high sensitivity cellular imaging, but time-gated OADF offers a second modality for true background-free detection. Our combined structural and spectroscopic data not only gives additional mechanistic details for designing optically modulated fluorescent proteins but also provides the opportunity to distinguish similarly emitting OMFPs through OADF and through their unique modulation spectra.
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Affiliation(s)
- Baijie Peng
- School of Chemistry & Biochemistry and Petit Institute for Biosciences and Bioengineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
| | - Ryan Dikdan
- School of Chemistry & Biochemistry and Petit Institute for Biosciences and Bioengineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
| | - Shannon E Hill
- School of Chemistry & Biochemistry and Petit Institute for Biosciences and Bioengineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
| | - Athéna C Patterson-Orazem
- School of Chemistry & Biochemistry and Petit Institute for Biosciences and Bioengineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
| | - Raquel L Lieberman
- School of Chemistry & Biochemistry and Petit Institute for Biosciences and Bioengineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
| | - Christoph J Fahrni
- School of Chemistry & Biochemistry and Petit Institute for Biosciences and Bioengineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
| | - Robert M Dickson
- School of Chemistry & Biochemistry and Petit Institute for Biosciences and Bioengineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
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12
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Gao Y, Saccuzzo EG, Hill SE, Huard DJE, Robang AS, Lieberman RL, Paravastu AK. Structural Arrangement within a Peptide Fibril Derived from the Glaucoma-Associated Myocilin Olfactomedin Domain. J Phys Chem B 2021; 125:2886-2897. [PMID: 33683890 DOI: 10.1021/acs.jpcb.0c11460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Myocilin-associated glaucoma is a new addition to the list of diseases linked to protein misfolding and amyloid formation. Single point variants of the ∼257-residue myocilin olfactomedin domain (mOLF) lead to mutant myocilin aggregation. Here, we analyze the 12-residue peptide P1 (GAVVYSGSLYFQ), corresponding to residues 326-337 of mOLF, previously shown to form amyloid fibrils in vitro and in silico. We applied solid-state NMR structural measurements to test the hypothesis that P1 fibrils adopt one of three predicted structures. Our data are consistent with a U-shaped fibril arrangement for P1, one that is related to the U-shape predicted previously in silico. Our data are also consistent with an antiparallel fibril arrangement, likely driven by terminal electrostatics. Our proposed structural model is reminiscent of fibrils formed by the Aβ(1-40) Iowa mutant peptide, but with a different arrangement of molecular turn regions. Taken together, our results strengthen the connection between mOLF fibrils and the broader amylome and contribute to our understanding of the fundamental molecular interactions governing fibril architecture and stability.
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13
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Webster JM, Darling AL, Sanders TA, Blazier DM, Vidal-Aguiar Y, Beaulieu-Abdelahad D, Plemmons DG, Hill SE, Uversky VN, Bickford PC, Dickey CA, Blair LJ. Hsp22 with an N-Terminal Domain Truncation Mediates a Reduction in Tau Protein Levels. Int J Mol Sci 2020; 21:E5442. [PMID: 32751642 PMCID: PMC7432035 DOI: 10.3390/ijms21155442] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 07/27/2020] [Accepted: 07/28/2020] [Indexed: 11/21/2022] Open
Abstract
Misfolding, aggregation and accumulation of proteins are toxic elements in the progression of a broad range of neurodegenerative diseases. Molecular chaperones enable a cellular defense by reducing or compartmentalizing these insults. Small heat shock proteins (sHsps) engage proteins early in the process of misfolding and can facilitate their proper folding or refolding, sequestration, or clearance. Here, we evaluate the effects of the sHsp Hsp22, as well as a pseudophosphorylated mutant and an N-terminal domain deletion (NTDΔ) variant on tau aggregation in vitro and tau accumulation and aggregation in cultured cells. Hsp22 wild-type (WT) protein had a significant inhibitory effect on heparin-induced aggregation in vitro and the pseudophosphorylated mutant Hsp22 demonstrated a similar effect. When co-expressed in a cell culture model with tau, these Hsp22 constructs significantly reduced soluble tau protein levels when transfected at a high ratio relative to tau. However, the Hsp22 NTDΔ protein drastically reduced the soluble protein expression levels of both tau WT and tau P301L/S320F even at lower transfection ratios, which resulted in a correlative reduction of the triton-insoluble tau P301L/S320F aggregates.
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Affiliation(s)
- Jack M. Webster
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33620, USA; (J.M.W.); (A.L.D.); (T.A.S.); (D.M.B.); (Y.V.-A.); (D.B.-A.); (D.G.P.); (S.E.H.); (V.N.U.); (C.A.D.)
- USF Health Byrd Alzheimer’s Institute, University of South Florida, Tampa, FL 33620, USA
| | - April L. Darling
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33620, USA; (J.M.W.); (A.L.D.); (T.A.S.); (D.M.B.); (Y.V.-A.); (D.B.-A.); (D.G.P.); (S.E.H.); (V.N.U.); (C.A.D.)
- USF Health Byrd Alzheimer’s Institute, University of South Florida, Tampa, FL 33620, USA
| | - Taylor A. Sanders
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33620, USA; (J.M.W.); (A.L.D.); (T.A.S.); (D.M.B.); (Y.V.-A.); (D.B.-A.); (D.G.P.); (S.E.H.); (V.N.U.); (C.A.D.)
- USF Health Byrd Alzheimer’s Institute, University of South Florida, Tampa, FL 33620, USA
| | - Danielle M. Blazier
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33620, USA; (J.M.W.); (A.L.D.); (T.A.S.); (D.M.B.); (Y.V.-A.); (D.B.-A.); (D.G.P.); (S.E.H.); (V.N.U.); (C.A.D.)
- USF Health Byrd Alzheimer’s Institute, University of South Florida, Tampa, FL 33620, USA
| | - Yamile Vidal-Aguiar
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33620, USA; (J.M.W.); (A.L.D.); (T.A.S.); (D.M.B.); (Y.V.-A.); (D.B.-A.); (D.G.P.); (S.E.H.); (V.N.U.); (C.A.D.)
- USF Health Byrd Alzheimer’s Institute, University of South Florida, Tampa, FL 33620, USA
| | - David Beaulieu-Abdelahad
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33620, USA; (J.M.W.); (A.L.D.); (T.A.S.); (D.M.B.); (Y.V.-A.); (D.B.-A.); (D.G.P.); (S.E.H.); (V.N.U.); (C.A.D.)
- USF Health Byrd Alzheimer’s Institute, University of South Florida, Tampa, FL 33620, USA
| | - Drew G. Plemmons
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33620, USA; (J.M.W.); (A.L.D.); (T.A.S.); (D.M.B.); (Y.V.-A.); (D.B.-A.); (D.G.P.); (S.E.H.); (V.N.U.); (C.A.D.)
- USF Health Byrd Alzheimer’s Institute, University of South Florida, Tampa, FL 33620, USA
| | - Shannon E. Hill
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33620, USA; (J.M.W.); (A.L.D.); (T.A.S.); (D.M.B.); (Y.V.-A.); (D.B.-A.); (D.G.P.); (S.E.H.); (V.N.U.); (C.A.D.)
- USF Health Byrd Alzheimer’s Institute, University of South Florida, Tampa, FL 33620, USA
| | - Vladimir N. Uversky
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33620, USA; (J.M.W.); (A.L.D.); (T.A.S.); (D.M.B.); (Y.V.-A.); (D.B.-A.); (D.G.P.); (S.E.H.); (V.N.U.); (C.A.D.)
| | - Paula C. Bickford
- Research Service, James A Haley Veterans Hospital, 13000 Bruce B Downs Blvd, Tampa, FL 33612, USA;
- Department of Neurosurgery and Brain Repair, Morsani College of Medicine, University of South Florida Health, 12901 Bruce B Downs Blvd, Tampa, FL 33612, USA
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida Health, 12901 Bruce B Downs Blvd, Tampa, FL 33612, USA
| | - Chad A. Dickey
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33620, USA; (J.M.W.); (A.L.D.); (T.A.S.); (D.M.B.); (Y.V.-A.); (D.B.-A.); (D.G.P.); (S.E.H.); (V.N.U.); (C.A.D.)
- USF Health Byrd Alzheimer’s Institute, University of South Florida, Tampa, FL 33620, USA
- Research Service, James A Haley Veterans Hospital, 13000 Bruce B Downs Blvd, Tampa, FL 33612, USA;
| | - Laura J. Blair
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33620, USA; (J.M.W.); (A.L.D.); (T.A.S.); (D.M.B.); (Y.V.-A.); (D.B.-A.); (D.G.P.); (S.E.H.); (V.N.U.); (C.A.D.)
- USF Health Byrd Alzheimer’s Institute, University of South Florida, Tampa, FL 33620, USA
- Research Service, James A Haley Veterans Hospital, 13000 Bruce B Downs Blvd, Tampa, FL 33612, USA;
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14
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Hill SE, Cho H, Raut P, Lieberman RL. Calcium-ligand variants of the myocilin olfactomedin propeller selected from invertebrate phyla reveal cross-talk with N-terminal blade and surface helices. Acta Crystallogr D Struct Biol 2019; 75:817-824. [PMID: 31478904 PMCID: PMC6719662 DOI: 10.1107/s205979831901074x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2019] [Accepted: 07/31/2019] [Indexed: 11/10/2022] Open
Abstract
Olfactomedins are a family of modular proteins found in multicellular organisms that all contain five-bladed β-propeller olfactomedin (OLF) domains. In support of differential functions for the OLF propeller, the available crystal structures reveal that only some OLF domains harbor an internal calcium-binding site with ligands derived from a triad of residues. For the myocilin OLF domain (myoc-OLF), ablation of the ion-binding site (triad Asp, Asn, Asp) by altering the coordinating residues affects the stability and overall structure, in one case leading to misfolding and glaucoma. Bioinformatics analysis reveals a variety of triads with possible ion-binding characteristics lurking in OLF domains in invertebrate chordates such as Arthropoda (Asp-Glu-Ser), Nematoda (Asp-Asp-His) and Echinodermata (Asp-Glu-Lys). To test ion binding and to extend the observed connection between ion binding and distal structural rearrangements, consensus triads from these phyla were installed in the myoc-OLF. All three protein variants exhibit wild-type-like or better stability, but their calcium-binding properties differ, concomitant with new structural deviations from wild-type myoc-OLF. Taken together, the results indicate that calcium binding is not intrinsically destabilizing to myoc-OLF or required to observe a well ordered side helix, and that ion binding is a differential feature that may underlie the largely elusive biological function of OLF propellers.
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Affiliation(s)
- Shannon E. Hill
- School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive NW, Atlanta, GA 30332-0400, USA
| | - Hayeon Cho
- School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive NW, Atlanta, GA 30332-0400, USA
| | - Priyam Raut
- School of Biological Sciences, Georgia Institute of Technology, 310 Ferst Drive NW, Atlanta, GA 30318, USA
| | - Raquel L. Lieberman
- School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive NW, Atlanta, GA 30332-0400, USA
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15
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Hill SE, Kwon MS, Martin MD, Suntharalingam A, Hazel A, Dickey CA, Gumbart JC, Lieberman RL. Stable calcium-free myocilin olfactomedin domain variants reveal challenges in differentiating between benign and glaucoma-causing mutations. J Biol Chem 2019; 294:12717-12728. [PMID: 31270212 PMCID: PMC6709634 DOI: 10.1074/jbc.ra119.009419] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 06/25/2019] [Indexed: 01/07/2023] Open
Abstract
Nonsynonymous gene mutations can be beneficial, neutral, or detrimental to the stability, structure, and biological function of the encoded protein, but the effects of these mutations are often not readily predictable. For example, the β-propeller olfactomedin domain of myocilin (mOLF) exhibits a complex interrelationship among structure(s), stability, and aggregation. Numerous mutations within mOLF are linked to glaucoma; the resulting variants are less stable, aggregation-prone, and sequestered intracellularly, causing cytotoxicity. Here, we report the first stable mOLF variants carrying substitutions in the calcium-binding site that exhibit solution characteristics indistinguishable from those of glaucoma variants. Crystal structures of these stable variants at 1.8-2.0-Å resolution revealed features that we could not predict by molecular dynamics simulations, including loss of loop structure, helix unwinding, and a blade shift. Double mutants that combined a stabilizing substitution and a selected glaucoma-causing single-point mutant rescued in vitro folding and stability defects. In the context of full-length myocilin, secretion of stable single variants was indistinguishable from that of the WT protein, and the double mutants were secreted to varying extents. In summary, our finding that mOLF can tolerate particular substitutions that render the protein stable despite a conformational switch emphasizes the complexities in differentiating between benign and glaucoma-causing variants and provides new insight into the possible biological function of myocilin.
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Affiliation(s)
- Shannon E. Hill
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Michelle S. Kwon
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Mackenzie D. Martin
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Amirthaa Suntharalingam
- Department of Molecular Medicine and Byrd Alzheimer's Research Institute, University of South Florida, Tampa, Florida 33613
| | - Anthony Hazel
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Chad A. Dickey
- Department of Molecular Medicine and Byrd Alzheimer's Research Institute, University of South Florida, Tampa, Florida 33613
| | - James C. Gumbart
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332,School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Raquel L. Lieberman
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, To whom correspondence should be addressed:
School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Dr. NW, Atlanta, GA 30332-0400. E-mail:
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16
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Patterson-Orazem AC, Hill SE, Wang Y, Dominic IM, Hall CK, Lieberman RL. Differential Misfolding Properties of Glaucoma-Associated Olfactomedin Domains from Humans and Mice. Biochemistry 2019; 58:1718-1727. [PMID: 30802039 DOI: 10.1021/acs.biochem.8b01309] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Mutations in myocilin, predominantly within its olfactomedin (OLF) domain, are causative for the heritable form of open angle glaucoma in humans. Surprisingly, mice expressing Tyr423His mutant myocilin, corresponding to a severe glaucoma-causing mutation (Tyr437His) in human subjects, exhibit a weak, if any, glaucoma phenotype. To address possible protein-level discrepancies between mouse and human OLFs, which might lead to this outcome, biophysical properties of mouse OLF were characterized for comparison with those of human OLF. The 1.55 Å resolution crystal structure of mouse OLF reveals an asymmetric 5-bladed β-propeller that is nearly indistinguishable from previous structures of human OLF. Wild-type and selected mutant mouse OLFs mirror thermal stabilities of their human OLF counterparts, including characteristic stabilization in the presence of calcium. Mouse OLF forms thioflavin T-positive aggregates with a similar end-point morphology as human OLF, but amyloid aggregation kinetic rates of mouse OLF are faster than human OLF. Simulations and experiments support the interpretation that kinetics of mouse OLF are faster because of a decreased charge repulsion arising from more neutral surface electrostatics. Taken together, phenotypic differences observed in mouse and human studies of mutant myocilin could be a function of aggregation kinetics rates, which would alter the lifetime of putatively toxic protofibrillar intermediates.
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Affiliation(s)
- Athéna C Patterson-Orazem
- School of Chemistry & Biochemistry , Georgia Institute of Technology , Atlanta , Georgia 30332-0400 , United States
| | - Shannon E Hill
- School of Chemistry & Biochemistry , Georgia Institute of Technology , Atlanta , Georgia 30332-0400 , United States
| | - Yiming Wang
- Department of Chemical & Biomolecular Engineering , North Carolina State University , Raleigh , North Carolina 27695-7905 , United States
| | - Iramofu M Dominic
- School of Chemistry & Biochemistry , Georgia Institute of Technology , Atlanta , Georgia 30332-0400 , United States
| | - Carol K Hall
- Department of Chemical & Biomolecular Engineering , North Carolina State University , Raleigh , North Carolina 27695-7905 , United States
| | - Raquel L Lieberman
- School of Chemistry & Biochemistry , Georgia Institute of Technology , Atlanta , Georgia 30332-0400 , United States
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17
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Wang Y, Gao Y, Hill SE, Huard DJE, Tomlin MO, Lieberman RL, Paravastu AK, Hall CK. Simulations and Experiments Delineate Amyloid Fibrilization by Peptides Derived from Glaucoma-Associated Myocilin. J Phys Chem B 2018; 122:5845-5850. [PMID: 29724098 DOI: 10.1021/acs.jpcb.8b03000] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Mutant myocilin aggregation is associated with inherited open angle glaucoma, a prevalent optic neuropathy leading to blindness. Comprehension of mutant myocilin aggregation is of fundamental importance to glaucoma pathogenesis and ties glaucoma to amyloid diseases such as Alzheimer's. Here, we probe the aggregation properties of peptides derived from the myocilin olfactomedin domain. Peptides P1 (residues 326-337) and P3 (residues 426-442) were identified previously to form amyloids. Coarse-grained discontinuous molecular dynamics simulations using the PRIME20 force field (DMD/PRIME20) predict that P1 and P3 are aggregation-prone; P1 consistently forms fibrillar aggregates with parallel in-register β-sheets, whereas P3 forms β-sheet-containing aggregates without distinct order. Natural abundance 13C solid-state NMR spectra validate that aggregated P1 exhibits amyloid signatures and is more homogeneous than aggregated P3. DMD/PRIME20 simulations provide a viable method to predict peptide aggregation propensities and aggregate structure/order which cannot be accessed by bioinformatics or readily attained experimentally.
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Affiliation(s)
- Yiming Wang
- Department of Chemical and Biomolecular Engineering , North Carolina State University , Raleigh , North Carolina 27695-7905 , United States
| | | | | | | | | | | | | | - Carol K Hall
- Department of Chemical and Biomolecular Engineering , North Carolina State University , Raleigh , North Carolina 27695-7905 , United States
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18
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Patterson-Orazem AC, Hill SE, Fautsch MP, Lieberman RL. Epitope mapping of commercial antibodies that detect myocilin. Exp Eye Res 2018; 173:109-112. [PMID: 29752947 DOI: 10.1016/j.exer.2018.05.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 04/17/2018] [Accepted: 05/05/2018] [Indexed: 01/26/2023]
Abstract
The presence of myocilin is often used in the process of validating trabecular meshwork (TM) cells and eye tissues, but the antibody reagents used for detection are poorly characterized. Indeed, for over a century, researchers have been using antibodies to track proteins of interest in a variety of biological contexts, but many antibodies remain ill-defined at the molecular level and in their target epitope. Such issues have prompted efforts from major funding agencies to validate reagents and combat reproducibility issues across biomedical sciences. Here we characterize the epitopes recognized by four commercial myocilin antibodies, aided by structurally and biochemically characterized myocilin fragments. All four antibodies recognize enriched myocilin secreted from human TM cell media. The detection of myocilin fragments by ELISA and Western blot reveal a variety of epitopes across the myocilin polypeptide chain. A more precise understanding of myocilin antibody targets, including conformational specificity, should aid the community in standardizing protocols across laboratories and in turn, lead to a better understanding of eye physiology and disease.
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Affiliation(s)
- Athéna C Patterson-Orazem
- School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, GA, 30332-0400, United States
| | - Shannon E Hill
- School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, GA, 30332-0400, United States
| | - Michael P Fautsch
- Department of Ophthalmology, Mayo Clinic, Rochester, MN, 55905, United States
| | - Raquel L Lieberman
- School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, GA, 30332-0400, United States.
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19
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Goldenzweig A, Goldsmith M, Hill SE, Gertman O, Laurino P, Ashani Y, Dym O, Unger T, Albeck S, Prilusky J, Lieberman RL, Aharoni A, Silman I, Sussman JL, Tawfik DS, Fleishman SJ. Automated Structure- and Sequence-Based Design of Proteins for High Bacterial Expression and Stability. Mol Cell 2018; 70:380. [PMID: 29677494 PMCID: PMC5919778 DOI: 10.1016/j.molcel.2018.03.035] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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20
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Hill SE, Nguyen E, Donegan RK, Patterson-Orazem AC, Hazel A, Gumbart JC, Lieberman RL. Structure and Misfolding of the Flexible Tripartite Coiled-Coil Domain of Glaucoma-Associated Myocilin. Structure 2017; 25:1697-1707.e5. [PMID: 29056483 PMCID: PMC5685557 DOI: 10.1016/j.str.2017.09.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 08/07/2017] [Accepted: 09/18/2017] [Indexed: 01/15/2023]
Abstract
Glaucoma-associated myocilin is a member of the olfactomedins, a protein family involved in neuronal development and human diseases. Molecular studies of the myocilin N-terminal coiled coil demonstrate a unique tripartite architecture: a Y-shaped parallel dimer-of-dimers with distinct tetramer and dimer regions. The structure of the dimeric C-terminal 7-heptad repeats elucidates an unexpected repeat pattern involving inter-strand stabilization by oppositely charged residues. Molecular dynamics simulations reveal an alternate accessible conformation in which the terminal inter-strand disulfide limits the extent of unfolding and results in a kinked configuration. By inference, full-length myocilin is also branched, with two pairs of C-terminal olfactomedin domains. Selected variants within the N-terminal region alter the apparent quaternary structure of myocilin but do so without compromising stability or causing aggregation. In addition to increasing our structural knowledge of naturally occurring extracellular coiled coils and biomedically important olfactomedins, this work broadens the scope of protein misfolding in the pathogenesis of myocilin-associated glaucoma.
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Affiliation(s)
- Shannon E Hill
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Elaine Nguyen
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Rebecca K Donegan
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | | | - Anthony Hazel
- School of Physics, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - James C Gumbart
- School of Physics, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Raquel L Lieberman
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, USA.
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21
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Hill SE, Nguyen E, Ukachukwu CU, Freeman DM, Quirk S, Lieberman RL. Metal ion coordination in the E. coli Nudix hydrolase dihydroneopterin triphosphate pyrophosphatase: New clues into catalytic mechanism. PLoS One 2017; 12:e0180241. [PMID: 28742822 PMCID: PMC5526541 DOI: 10.1371/journal.pone.0180241] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Accepted: 06/12/2017] [Indexed: 01/02/2023] Open
Abstract
Dihydroneopterin triphosphate pyrophosphatase (DHNTPase), a member of the Mg2+ dependent Nudix hydrolase superfamily, is the recently-discovered enzyme that functions in the second step of the pterin branch of the folate biosynthetic pathway in E. coli. DHNTPase is of interest because inhibition of enzymes in bacterial folate biosynthetic pathways is a strategy for antibiotic development. We determined crystal structures of DHNTPase with and without activating, Mg2+-mimicking metals Co2+ and Ni2+. Four metal ions, identified by anomalous scattering, and stoichiometrically confirmed in solution by isothermal titration calorimetry, are held in place by Glu56 and Glu60 within the Nudix sequence motif, Glu117, waters, and a sulfate ion, of which the latter is further stabilized by a salt bridge with Lys7. In silico docking of the DHNTP substrate reveals a binding mode in which the pterin ring moiety is nestled in a largely hydrophobic pocket, the β-phosphate activated for nucleophilic attack overlays with the crystallographic sulfate and is in line with an activated water molecule, and remaining phosphate groups are stabilized by all four identified metal ions. The structures and binding data provide new details regarding DHNTPase metal requirements, mechanism, and suggest a strategy for efficient inhibition.
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Affiliation(s)
- Shannon E. Hill
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, United States of America
| | - Elaine Nguyen
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, United States of America
| | - Chiamaka U. Ukachukwu
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, United States of America
| | - Dana M. Freeman
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, United States of America
| | - Stephen Quirk
- Kimberly-Clark Corporation, Roswell, Georgia, United States of America
| | - Raquel L. Lieberman
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, United States of America
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22
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Goldenzweig A, Goldsmith M, Hill SE, Gertman O, Laurino P, Ashani Y, Dym O, Unger T, Albeck S, Prilusky J, Lieberman RL, Aharoni A, Silman I, Sussman JL, Tawfik DS, Fleishman SJ. Automated Structure- and Sequence-Based Design of Proteins for High Bacterial Expression and Stability. Mol Cell 2016; 63:337-346. [PMID: 27425410 PMCID: PMC4961223 DOI: 10.1016/j.molcel.2016.06.012] [Citation(s) in RCA: 277] [Impact Index Per Article: 34.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Revised: 05/18/2016] [Accepted: 06/07/2016] [Indexed: 12/28/2022]
Abstract
Upon heterologous overexpression, many proteins misfold or aggregate, thus resulting in low functional yields. Human acetylcholinesterase (hAChE), an enzyme mediating synaptic transmission, is a typical case of a human protein that necessitates mammalian systems to obtain functional expression. We developed a computational strategy and designed an AChE variant bearing 51 mutations that improved core packing, surface polarity, and backbone rigidity. This variant expressed at ∼2,000-fold higher levels in E. coli compared to wild-type hAChE and exhibited 20°C higher thermostability with no change in enzymatic properties or in the active-site configuration as determined by crystallography. To demonstrate broad utility, we similarly designed four other human and bacterial proteins. Testing at most three designs per protein, we obtained enhanced stability and/or higher yields of soluble and active protein in E. coli. Our algorithm requires only a 3D structure and several dozen sequences of naturally occurring homologs, and is available at http://pross.weizmann.ac.il. A new computational method is used to stabilize five recalcitrant proteins Designed variants show higher expression and stability with unmodified function A designed human acetylcholinesterase variant expresses solubly in bacteria The method is fully automated and implemented on a webserver
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Affiliation(s)
- Adi Goldenzweig
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Moshe Goldsmith
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Shannon E Hill
- School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400, USA
| | - Or Gertman
- Department of Life Sciences, Ben-Gurion University of the Negev, P.O.B. 653, Beer-Sheva 8410501, Israel
| | - Paola Laurino
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Yacov Ashani
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel; Israel Structural Proteomics Center, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Orly Dym
- Israel Structural Proteomics Center, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Tamar Unger
- Israel Structural Proteomics Center, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Shira Albeck
- Israel Structural Proteomics Center, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Jaime Prilusky
- Bioinformatics & Biological Computing Unit, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Raquel L Lieberman
- School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400, USA
| | - Amir Aharoni
- Department of Life Sciences, Ben-Gurion University of the Negev, P.O.B. 653, Beer-Sheva 8410501, Israel
| | - Israel Silman
- Department of Neurobiology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Joel L Sussman
- Israel Structural Proteomics Center, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Dan S Tawfik
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel.
| | - Sarel J Fleishman
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel.
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23
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Naing SH, Vukoti KM, Drury JE, Johnson JL, Kalyoncu S, Hill SE, Torres MP, Lieberman RL. Catalytic Properties of Intramembrane Aspartyl Protease Substrate Hydrolysis Evaluated Using a FRET Peptide Cleavage Assay. ACS Chem Biol 2015; 10:2166-74. [PMID: 26118406 DOI: 10.1021/acschembio.5b00305] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Chemical details of intramembrane proteolysis remain elusive despite its prevalence throughout biology. We developed a FRET peptide assay for the intramembrane aspartyl protease (IAP) from Methanoculleus marisnigri JR1 in combination with quantitative mass spectrometry cleavage site analysis. IAP can hydrolyze the angiotensinogen sequence, a substrate for the soluble aspartyl protease renin, at a predominant cut site, His-Thr. Turnover is slow (min(-1) × 10(-3)), affinity and Michaelis constant (Km) values are in the low micromolar range, and both catalytic rates and cleavage sites are the same in detergent as reconstituted into bicelles. Three well-established, IAP-directed inhibitors were directly confirmed as competitive, albeit with modest inhibitor constant (Ki) values. Partial deletion of the first transmembrane helix results in a biophysically similar but less active enzyme than full-length IAP, indicating a catalytic role. Our study demonstrates previously unappreciated similarities with soluble aspartyl proteases, provides new biochemical features of IAP and inhibitors, and offers tools to study other intramembrane protease family members in molecular detail.
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Affiliation(s)
- Swe-Htet Naing
- School
of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic
Drive Northwest, Atlanta, Georgia 30332-0400, United States
| | - Krishna M. Vukoti
- School
of Biology, Georgia Institute of Technology, 310 Ferst Drive Northwest, Atlanta, Georgia 30332-0230, United States
| | - Jason E. Drury
- School
of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic
Drive Northwest, Atlanta, Georgia 30332-0400, United States
| | - Jennifer L. Johnson
- School
of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic
Drive Northwest, Atlanta, Georgia 30332-0400, United States
| | - Sibel Kalyoncu
- School
of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic
Drive Northwest, Atlanta, Georgia 30332-0400, United States
| | - Shannon E. Hill
- School
of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic
Drive Northwest, Atlanta, Georgia 30332-0400, United States
| | - Matthew P. Torres
- School
of Biology, Georgia Institute of Technology, 310 Ferst Drive Northwest, Atlanta, Georgia 30332-0230, United States
| | - Raquel L. Lieberman
- School
of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic
Drive Northwest, Atlanta, Georgia 30332-0400, United States
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24
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Hill SE, Donegan RK, Nguyen E, Desai TM, Lieberman RL. Molecular Details of Olfactomedin Domains Provide Pathway to Structure-Function Studies. PLoS One 2015; 10:e0130888. [PMID: 26121352 PMCID: PMC4488277 DOI: 10.1371/journal.pone.0130888] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 05/26/2015] [Indexed: 11/18/2022] Open
Abstract
Olfactomedin (OLF) domains are found within extracellular, multidomain proteins in numerous tissues of multicellular organisms. Even though these proteins have been implicated in human disorders ranging from cancers to attention deficit disorder to glaucoma, little is known about their structure(s) and function(s). Here we biophysically, biochemically, and structurally characterize OLF domains from H. sapiens olfactomedin-1 (npoh-OLF, also called noelin, pancortin, OLFM1, and hOlfA), and M. musculus gliomedin (glio-OLF, also called collomin, collmin, and CRG-L2), and compare them with available structures of myocilin (myoc-OLF) recently reported by us and R. norvegicus glio-OLF and M. musculus latrophilin-3 (lat3-OLF) by others. Although the five-bladed β-propeller architecture remains unchanged, numerous physicochemical characteristics differ among these OLF domains. First, npoh-OLF and glio-OLF exhibit prominent, yet distinct, positive surface charges and copurify with polynucleotides. Second, whereas npoh-OLF and myoc-OLF exhibit thermal stabilities typical of human proteins near 55°C, and most myoc-OLF variants are destabilized and highly prone to aggregation, glio-OLF is nearly 20°C more stable and significantly more resistant to chemical denaturation. Phylogenetically, glio-OLF is most similar to primitive OLFs, and structurally, glio-OLF is missing distinguishing features seen in OLFs such as the disulfide bond formed by N- and C- terminal cysteines, the sequestered Ca2+ ion within the propeller central hydrophilic cavity, and a key loop-stabilizing cation-π interaction on the top face of npoh-OLF and myoc-OLF. While deciphering the explicit biological functions, ligands, and binding partners for OLF domains will likely continue to be a challenging long-term experimental pursuit, we used structural insights gained here to generate a new antibody selective for myoc-OLF over npoh-OLF and glio-OLF as a first step in overcoming the impasse in detailed functional characterization of these biomedically important protein domains.
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Affiliation(s)
- Shannon E. Hill
- School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, United States of America
| | - Rebecca K. Donegan
- School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, United States of America
| | - Elaine Nguyen
- School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, United States of America
| | - Tanay M. Desai
- School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, United States of America
| | - Raquel L. Lieberman
- School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, United States of America
- * E-mail:
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25
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Richardson EA, Hill SE, Mitchell R, Pearce J, Shortt NK. Is local alcohol outlet density related to alcohol-related morbidity and mortality in Scottish cities? Health Place 2015; 33:172-80. [PMID: 25840352 PMCID: PMC4415114 DOI: 10.1016/j.healthplace.2015.02.014] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Revised: 02/17/2015] [Accepted: 02/24/2015] [Indexed: 11/07/2022]
Abstract
Alcohol consumption may be influenced by the local alcohol retailing environment. This study is the first to examine neighbourhood alcohol outlet availability (on- and off-sales outlets) and alcohol-related health outcomes in Scotland. Alcohol-related hospitalisations and deaths were significantly higher in neighbourhoods with higher outlet densities, and off-sales outlets were more important than on-sales outlets. The relationships held for most age groups, including those under the legal minimum drinking age, although were not significant for the youngest legal drinkers (18–25 years). Alcohol-related deaths and hospitalisations were higher in more income-deprived neighbourhoods, and the gradient in deaths (but not hospitalisations) was marginally larger in neighbourhoods with higher off-sales outlet densities. Efforts to reduce alcohol-related harm should consider the potentially important role of the alcohol retail environment. Whether alcohol outlet availability influences health in Scotland was unknown We assessed relationships with alcohol-related hospitalisations and mortality More hospitalisations and deaths occurred in areas with greater outlet availability Off-sales outlets were more important for health than on-sales outlets Efforts to reduce alcohol harms should consider the alcohol retail environment
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Affiliation(s)
- E A Richardson
- Centre for Research on Environment, Society and Health (CRESH), School of GeoSciences, University of Edinburgh, Edinburgh EH8 9XP, UK.
| | - S E Hill
- Global Public Health Unit, School of Social and Political Science, University of Edinburgh, EH8 9LD, UK.
| | - R Mitchell
- Centre for Research on Environment, Society and Health (CRESH), Section of Public Health and Health Policy, Faculty of Medicine, University of Glasgow, Glasgow G12 8RZ, UK.
| | - J Pearce
- Centre for Research on Environment, Society and Health (CRESH), School of GeoSciences, University of Edinburgh, Edinburgh EH8 9XP, UK.
| | - N K Shortt
- Centre for Research on Environment, Society and Health (CRESH), School of GeoSciences, University of Edinburgh, Edinburgh EH8 9XP, UK.
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26
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Donegan RK, Hill SE, Freeman DM, Nguyen E, Orwig SD, Turnage KC, Lieberman RL. Structural basis for misfolding in myocilin-associated glaucoma. Hum Mol Genet 2014; 24:2111-24. [PMID: 25524706 DOI: 10.1093/hmg/ddu730] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Olfactomedin (OLF) domain-containing proteins play roles in fundamental cellular processes and have been implicated in disorders ranging from glaucoma, cancers and inflammatory bowel disorder, to attention deficit disorder and childhood obesity. We solved crystal structures of the OLF domain of myocilin (myoc-OLF), the best studied such domain to date. Mutations in myoc-OLF are causative in the autosomal dominant inherited form of the prevalent ocular disorder glaucoma. The structures reveal a new addition to the small family of five-bladed β-propellers. Propellers are most well known for their ability to act as hubs for protein-protein interactions, a function that seems most likely for myoc-OLF, but they can also act as enzymes. A calcium ion, sodium ion and glycerol molecule were identified within a central hydrophilic cavity that is accessible via movements of surface loop residues. By mapping familial glaucoma-associated lesions onto the myoc-OLF structure, three regions sensitive to aggregation have been identified, with direct applicability to differentiating between neutral and disease-causing non-synonymous mutations documented in the human population worldwide. Evolutionary analysis mapped onto the myoc-OLF structure reveals conserved and divergent regions for possible overlapping and distinctive functional protein-protein or protein-ligand interactions across the broader OLF domain family. While deciphering the specific normal biological functions, ligands and binding partners for OLF domains will likely continue to be a challenging long-term experimental pursuit, atomic detail structural knowledge of myoc-OLF is a valuable guide for understanding the implications of glaucoma-associated mutations and will help focus future studies of this biomedically important domain family.
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Affiliation(s)
- Rebecca K Donegan
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400, USA
| | - Shannon E Hill
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400, USA
| | - Dana M Freeman
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400, USA
| | - Elaine Nguyen
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400, USA
| | - Susan D Orwig
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400, USA
| | - Katherine C Turnage
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400, USA
| | - Raquel L Lieberman
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400, USA
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27
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Orwig SD, Chi PV, Du Y, Hill SE, Cavitt MA, Suntharalingam A, Turnage KC, Dickey CA, France S, Fu H, Lieberman RL. Ligands for glaucoma-associated myocilin discovered by a generic binding assay. ACS Chem Biol 2014; 9:517-25. [PMID: 24279319 DOI: 10.1021/cb4007776] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Mutations in the olfactomedin domain of myocilin (myoc-OLF) are the strongest link to inherited primary open angle glaucoma. In this recently identified protein misfolding disorder, aggregation-prone disease variants of myocilin hasten glaucoma-associated elevation of intraocular pressure, leading to vision loss. Despite its well-documented pathogenic role, myocilin remains a domain of unknown structure or function. Here we report the first small-molecule ligands that bind to the native state of myoc-OLF. To discover these molecules, we designed a general label-free, mix-and-measure, high throughput chemical assay for restabilization (CARS), which is likely readily adaptable to discover ligands for other proteins. Of the 14 hit molecules identified from screening myoc-OLF against the Sigma-Aldrich Library of Pharmacologically Active Compounds using CARS, surface plasmon resonance binding studies reveal three are stoichiometric ligand scaffolds with low micromolar affinity. Two compounds, GW5074 and apigenin, inhibit myoc-OLF amyloid formation in vitro. Structure-activity relationship-based soluble derivatives reduce aggregation in vitro as well as enhance secretion of full-length mutant myocilin in a cell culture model. Our compounds set the stage for a new chemical probe approach to clarify the biological function of wild-type myocilin and represent lead therapeutic compounds for diminishing intracellular sequestration of toxic mutant myocilin.
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Affiliation(s)
- Susan D. Orwig
- School of Chemistry & Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive NW, Atlanta, Georgia 30332-0400, United States
| | - Pamela V. Chi
- School of Chemistry & Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive NW, Atlanta, Georgia 30332-0400, United States
| | - Yuhong Du
- Department
of Pharmacology, Emory University School of Medicine, 1510 Clifton
Road, Atlanta, Georgia 30322, United States
| | - Shannon E. Hill
- School of Chemistry & Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive NW, Atlanta, Georgia 30332-0400, United States
| | - Marchello A. Cavitt
- School of Chemistry & Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive NW, Atlanta, Georgia 30332-0400, United States
| | - Amrithaa Suntharalingam
- Department
of Molecular Medicine and Byrd Alzheimer’s Research Institute, University of South Florida, 4001 E. Fletcher Ave. Tampa, Florida 33613, United States
| | - Katherine C. Turnage
- School of Chemistry & Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive NW, Atlanta, Georgia 30332-0400, United States
| | - Chad A. Dickey
- Department
of Molecular Medicine and Byrd Alzheimer’s Research Institute, University of South Florida, 4001 E. Fletcher Ave. Tampa, Florida 33613, United States
| | - Stefan France
- School of Chemistry & Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive NW, Atlanta, Georgia 30332-0400, United States
| | - Haian Fu
- Department
of Pharmacology, Emory University School of Medicine, 1510 Clifton
Road, Atlanta, Georgia 30322, United States
| | - Raquel L. Lieberman
- School of Chemistry & Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive NW, Atlanta, Georgia 30332-0400, United States
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28
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Hill SE, Donegan RK, Lieberman RL. The glaucoma-associated olfactomedin domain of myocilin forms polymorphic fibrils that are constrained by partial unfolding and peptide sequence. J Mol Biol 2013; 426:921-35. [PMID: 24333014 DOI: 10.1016/j.jmb.2013.12.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 11/06/2013] [Accepted: 12/02/2013] [Indexed: 12/26/2022]
Abstract
The glaucoma-associated olfactomedin domain of myocilin (myoc-OLF) is a recent addition to the growing list of disease-associated amyloidogenic proteins. Inherited, disease-causing myocilin variants aggregate intracellularly instead of being secreted to the trabecular meshwork, which is a scenario toxic to trabecular meshwork cells and leads to early onset of ocular hypertension, the major risk factor for glaucoma. Here we systematically structurally and biophysically dissected myoc-OLF to better understand its amyloidogenesis. Under mildly destabilizing conditions, wild-type myoc-OLF adopts non-native structures that readily fibrillize when incubated at a temperature just below the transition for tertiary unfolding. With buffers at physiological pH, two main endpoint fibril morphologies are observed: (a) straight fibrils common to many amyloids and (b) unique micron-length, ~300 nm or larger diameter, species that lasso oligomers, which also exhibit classical spectroscopic amyloid signatures. Three disease-causing variants investigated herein exhibit non-native tertiary structures under physiological conditions, leading to a variety of growth rates and a fibril morphologies. In particular, the well-documented D380A variant, which lacks calcium, forms large circular fibrils. Two amyloid-forming peptide stretches have been identified, one for each of the main fibril morphologies observed. Our study places myoc-OLF within the larger landscape of the amylome and provides insight into the diversity of myoc-OLF aggregation that plays a role in glaucoma pathogenesis.
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Affiliation(s)
- Shannon E Hill
- School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive Northwest, Atlanta, GA 30332-0400, USA
| | - Rebecca K Donegan
- School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive Northwest, Atlanta, GA 30332-0400, USA
| | - Raquel L Lieberman
- School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive Northwest, Atlanta, GA 30332-0400, USA.
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Foley J, Hill SE, Miti T, Mulaj M, Ciesla M, Robeel R, Persichilli C, Raynes R, Westerheide S, Muschol M. Structural fingerprints and their evolution during oligomeric vs. oligomer-free amyloid fibril growth. J Chem Phys 2013; 139:121901. [PMID: 24089713 PMCID: PMC3716784 DOI: 10.1063/1.4811343] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Accepted: 05/03/2013] [Indexed: 11/14/2022] Open
Abstract
Deposits of fibrils formed by disease-specific proteins are the molecular hallmark of such diverse human disorders as Alzheimer's disease, type II diabetes, or rheumatoid arthritis. Amyloid fibril formation by structurally and functionally unrelated proteins exhibits many generic characteristics, most prominently the cross β-sheet structure of their mature fibrils. At the same time, amyloid formation tends to proceed along one of two separate assembly pathways yielding either stiff monomeric filaments or globular oligomers and curvilinear protofibrils. Given the focus on oligomers as major toxic species, the very existence of an oligomer-free assembly pathway is significant. Little is known, though, about the structure of the various intermediates emerging along different pathways and whether the pathways converge towards a common or distinct fibril structures. Using infrared spectroscopy we probed the structural evolution of intermediates and late-stage fibrils formed during in vitro lysozyme amyloid assembly along an oligomeric and oligomer-free pathway. Infrared spectroscopy confirmed that both pathways produced amyloid-specific β-sheet peaks, but at pathway-specific wavenumbers. We further found that the amyloid-specific dye thioflavin T responded to all intermediates along either pathway. The relative amplitudes of thioflavin T fluorescence responses displayed pathway-specific differences and could be utilized for monitoring the structural evolution of intermediates. Pathway-specific structural features obtained from infrared spectroscopy and Thioflavin T responses were identical for fibrils grown at highly acidic or at physiological pH values and showed no discernible effects of protein hydrolysis. Our results suggest that late-stage fibrils formed along either pathway are amyloidogenic in nature, but have distinguishable structural fingerprints. These pathway-specific fingerprints emerge during the earliest aggregation events and persist throughout the entire cascade of aggregation intermediates formed along each pathway.
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Affiliation(s)
- Joseph Foley
- Department of Physics, University of South Florida, Tampa, Florida 33620, USA
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Blair LJ, Nordhues BA, Hill SE, Scaglione KM, O'Leary JC, Fontaine SN, Breydo L, Zhang B, Li P, Wang L, Cotman C, Paulson HL, Muschol M, Uversky VN, Klengel T, Binder EB, Kayed R, Golde TE, Berchtold N, Dickey CA. Accelerated neurodegeneration through chaperone-mediated oligomerization of tau. J Clin Invest 2013; 123:4158-69. [PMID: 23999428 DOI: 10.1172/jci69003] [Citation(s) in RCA: 206] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Accepted: 06/27/2013] [Indexed: 12/22/2022] Open
Abstract
Aggregation of tau protein in the brain is associated with a class of neurodegenerative diseases known as tauopathies. FK506 binding protein 51 kDa (FKBP51, encoded by FKBP5) forms a mature chaperone complex with Hsp90 that prevents tau degradation. In this study, we have shown that tau levels are reduced throughout the brains of Fkbp5-/- mice. Recombinant FKBP51 and Hsp90 synergized to block tau clearance through the proteasome, resulting in tau oligomerization. Overexpression of FKBP51 in a tau transgenic mouse model revealed that FKBP51 preserved the species of tau that have been linked to Alzheimer's disease (AD) pathogenesis, blocked amyloid formation, and decreased tangle load in the brain. Alterations in tau turnover and aggregate structure corresponded with enhanced neurotoxicity in mice. In human brains, FKBP51 levels increased relative to age and AD, corresponding with demethylation of the regulatory regions in the FKBP5 gene. We also found that higher FKBP51 levels were associated with AD progression. Our data support a model in which age-associated increases in FKBP51 levels and its interaction with Hsp90 promote neurotoxic tau accumulation. Strategies aimed at attenuating FKBP51 levels or its interaction with Hsp90 have the potential to be therapeutically relevant for AD and other tauopathies.
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Hill SE, Stafford LM, Chi PV, Lieberman RL. Non-Native Structural Properties of the Glaucoma-Associated Olfactomedin Domain of Myocilin Lead to Amyloid Fibrils. Biophys J 2013. [DOI: 10.1016/j.bpj.2012.11.314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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32
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Muschol M, Hill SE, Ciesla M, Robeel R, Miti T, Foley J, Persichilli C, Mulaj M, Raynes R, Westerheide S. Structural Evolution of Oligomeric Vs. Oligomer-Free Amyloid Fibril Growth. Biophys J 2013. [DOI: 10.1016/j.bpj.2012.11.310] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Donegan RK, Hill SE, Turnage KC, Orwig SD, Lieberman RL. The glaucoma-associated olfactomedin domain of myocilin is a novel calcium binding protein. J Biol Chem 2012; 287:43370-7. [PMID: 23129764 DOI: 10.1074/jbc.m112.408906] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Myocilin is a protein found in the trabecular meshwork extracellular matrix tissue of the eye that plays a role in regulating intraocular pressure. Both wild-type and certain myocilin variants containing mutations in the olfactomedin (OLF) domain are linked to the optic neuropathy glaucoma. Because calcium ions are important biological cofactors that play numerous roles in extracellular matrix proteins, we examined the calcium binding properties of the myocilin OLF domain (myoc-OLF). Our study reveals an unprecedented high affinity calcium binding site within myoc-OLF. The calcium ion remains bound to wild-type OLF at neutral and acidic pH. A glaucoma-causing OLF variant, myoc-OLF(D380A), is calcium-depleted. Key differences in secondary and tertiary structure between myoc-OLF(D380A) and wild-type myoc-OLF, as well as limited access to chelators, indicate that the calcium binding site is largely buried in the interior of the protein. Analysis of six conserved aspartate or glutamate residues and an additional 18 disease-causing variants revealed two other candidate residues that may be involved in calcium coordination. Our finding expands our knowledge of calcium binding in extracellular matrix proteins; provides new clues into domain structure, function, and pathogenesis for myocilin; and offers insights into highly conserved, biomedically relevant OLF domains.
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Affiliation(s)
- Rebecca K Donegan
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, USA
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Suntharalingam A, Abisambra JF, O'Leary JC, Koren J, Zhang B, Joe MK, Blair LJ, Hill SE, Jinwal UK, Cockman M, Duerfeldt AS, Tomarev S, Blagg BSJ, Lieberman RL, Dickey CA. Glucose-regulated protein 94 triage of mutant myocilin through endoplasmic reticulum-associated degradation subverts a more efficient autophagic clearance mechanism. J Biol Chem 2012; 287:40661-9. [PMID: 23035116 DOI: 10.1074/jbc.m112.384800] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND Mutant myocilin accumulates in the endoplasmic reticulum for unknown reasons. RESULTS Glucose-regulated protein (Grp) 94 depletion reduces mutant myocilin by engaging autophagy. CONCLUSION Grp94 triages mutant myocilin through ER-associated degradation, subverting autophagy. SIGNIFICANCE Treating glaucoma could be possible by inhibiting Grp94 and reducing its novel client, mutant myocilin. Clearance of misfolded proteins in the endoplasmic reticulum (ER) is traditionally handled by ER-associated degradation (ERAD), a process that requires retro-translocation and ubiquitination mediated by a luminal chaperone network. Here we investigated whether the secreted, glaucoma-associated protein myocilin was processed by this pathway. Myocilin is typically transported through the ER/Golgi network, but inherited mutations in myocilin lead to its misfolding and aggregation within trabecular meshwork cells, and ultimately, ER stress-induced cell death. Using targeted knockdown strategies, we determined that glucose-regulated protein 94 (Grp94), the ER equivalent of heat shock protein 90 (Hsp90), specifically recognizes mutant myocilin, triaging it through ERAD. The addition of mutant myocilin to the short list of Grp94 clients strengthens the hypothesis that β-strand secondary structure drives client association with Grp94. Interestingly, the ERAD pathway is incapable of efficiently handling the removal of mutant myocilin, but when Grp94 is depleted, degradation of mutant myocilin is shunted away from ERAD toward a more robust clearance pathway for aggregation-prone proteins, the autophagy system. Thus ERAD inefficiency for distinct aggregation-prone proteins can be subverted by manipulating ER chaperones, leading to more effective clearance by the autophagic/lysosomal pathway. General Hsp90 inhibitors and a selective Grp94 inhibitor also facilitate clearance of mutant myocilin, suggesting that therapeutic approaches aimed at inhibiting Grp94 could be beneficial for patients suffering from some cases of myocilin glaucoma.
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Affiliation(s)
- Amirthaa Suntharalingam
- Department of Molecular Medicine and Byrd Alzheimer's Research Institute, University of South Florida, Tampa, FL 33613, USA
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Daughdrill GW, Kashtanov S, Stancik A, Hill SE, Helms G, Muschol M, Receveur-Bréchot V, Ytreberg FM. Understanding the structural ensembles of a highly extended disordered protein. Mol Biosyst 2011; 8:308-19. [PMID: 21979461 DOI: 10.1039/c1mb05243h] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Developing a comprehensive description of the equilibrium structural ensembles for intrinsically disordered proteins (IDPs) is essential to understanding their function. The p53 transactivation domain (p53TAD) is an IDP that interacts with multiple protein partners and contains numerous phosphorylation sites. Multiple techniques were used to investigate the equilibrium structural ensemble of p53TAD in its native and chemically unfolded states. The results from these experiments show that the native state of p53TAD has dimensions similar to a classical random coil while the chemically unfolded state is more extended. To investigate the molecular properties responsible for this behavior, a novel algorithm that generates diverse and unbiased structural ensembles of IDPs was developed. This algorithm was used to generate a large pool of plausible p53TAD structures that were reweighted to identify a subset of structures with the best fit to small angle X-ray scattering data. High weight structures in the native state ensemble show features that are localized to protein binding sites and regions with high proline content. The features localized to the protein binding sites are mostly eliminated in the chemically unfolded ensemble; while, the regions with high proline content remain relatively unaffected. Data from NMR experiments support these results, showing that residues from the protein binding sites experience larger environmental changes upon unfolding by urea than regions with high proline content. This behavior is consistent with the urea-induced exposure of nonpolar and aromatic side-chains in the protein binding sites that are partially excluded from solvent in the native state ensemble.
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Affiliation(s)
- Gary W Daughdrill
- Department of Cell Biology, Microbiology, and Molecular, University of South Florida, Tampa, FL 33612, USA
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Hill SE, Miti T, Richmond T, Muschol M. Spatial extent of charge repulsion regulates assembly pathways for lysozyme amyloid fibrils. PLoS One 2011; 6:e18171. [PMID: 21483680 PMCID: PMC3071722 DOI: 10.1371/journal.pone.0018171] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2010] [Accepted: 02/22/2011] [Indexed: 11/19/2022] Open
Abstract
Formation of large protein fibrils with a characteristic cross β-sheet architecture is the key indicator for a wide variety of systemic and neurodegenerative amyloid diseases. Recent experiments have strongly implicated oligomeric intermediates, transiently formed during fibril assembly, as critical contributors to cellular toxicity in amyloid diseases. At the same time, amyloid fibril assembly can proceed along different assembly pathways that might or might not involve such oligomeric intermediates. Elucidating the mechanisms that determine whether fibril formation proceeds along non-oligomeric or oligomeric pathways, therefore, is important not just for understanding amyloid fibril assembly at the molecular level but also for developing new targets for intervening with fibril formation. We have investigated fibril formation by hen egg white lysozyme, an enzyme for which human variants underlie non-neuropathic amyloidosis. Using a combination of static and dynamic light scattering, atomic force microscopy and circular dichroism, we find that amyloidogenic lysozyme monomers switch between three different assembly pathways: from monomeric to oligomeric fibril assembly and, eventually, disordered precipitation as the ionic strength of the solution increases. Fibril assembly only occurred under conditions of net repulsion among the amyloidogenic monomers while net attraction caused precipitation. The transition from monomeric to oligomeric fibril assembly, in turn, occurred as salt-mediated charge screening reduced repulsion among individual charged residues on the same monomer. We suggest a model of amyloid fibril formation in which repulsive charge interactions are a prerequisite for ordered fibril assembly. Furthermore, the spatial extent of non-specific charge screening selects between monomeric and oligomeric assembly pathways by affecting which subset of denatured states can form suitable intermolecular bonds and by altering the energetic and entropic requirements for the initial intermediates emerging along the monomeric vs. oligomeric assembly path.
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Affiliation(s)
- Shannon E. Hill
- Department of Physics, University of South Florida, Tampa, Florida, United States of America
| | - Tatiana Miti
- Department of Physics, University of South Florida, Tampa, Florida, United States of America
| | - Tyson Richmond
- Department of Physics, University of South Florida, Tampa, Florida, United States of America
| | - Martin Muschol
- Department of Physics, University of South Florida, Tampa, Florida, United States of America
- * E-mail:
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Abstract
The results of applying chloroform and KCl to Nitella indicate that a negative variation may be started whenever it is possible to set up along the protoplasm a gradient of potential difference sufficiently steep to produce the necessary outward flow of current. Successive variations may thus be set up.
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Affiliation(s)
- W J Osterhout
- Laboratories of The Rockefeller Institute for Medical Research
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39
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Abstract
Treatment of Nitella with distilled water apparently removes from the cell something which is responsible for the normal irritability and the potassium effect, (i.e. the large P.D. between a spot in contact with 0.01 M KCl and one in contact with 0.01 M NaCl). Presumably this substance (called R) is partially removed from the protoplasm by the distilled water. When this has happened a pinch which forces sap out into the protoplasm can restore its normal behavior. The treatment with distilled water which removes the potassium effect from the outer protoplasmic surface does not seem to affect the inner protoplasmic surface in the same way since the latter retains the outwardly directed potential which is apparently due to the potassium in the sap. But the inner surface appears to be affected in such fashion as to prevent the increase in its permeability which is necessary for the production of an action current. The pinch restores its normal behavior, presumably by forcing R from the sap into the protoplasm.
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Affiliation(s)
- S E Hill
- Laboratories of The Rockefeller Institute for Medical Research
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40
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Abstract
Suitable concentrations of ethyl alcohol (1 to 1.5 M) applied to a spot on a cell of Nitella lower the P.D. enough to cause action currents. The alcohol then suppresses action currents arriving from other parts of the cell and acts as a block. After the alcohol is removed the normal P.D. and irritability return.
Similar experiments on the sciatic nerve and skin of the frog produced only a negative result.
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Affiliation(s)
- W J Osterhout
- Laboratories of The Rockefeller Institute for Medical Research
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41
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Abstract
The reversible electrical variations hitherto described for plants and animals consist in a reversible loss of positive potential at a stimulated spot by which it becomes more negative. In this paper we describe changes which consist in a reversible loss of negative potential at a stimulated spot whereby it becomes more positive. We suggest that this be called a positive variation. The stimulation was produced in all cases by pinching or bending the cell. This produced a compression wave which traveled along the cell, producing a negative variation at a spot which was positive and a positive variation at a spot which was negative (due to application of 0.1 M KCl). The response produced by the compression wave differs in several respects from an ordinary propagated negative variation and may be termed a positive mechanical variation.
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Affiliation(s)
- W J Osterhout
- Laboratories of The Rockefeller Institute for Medical Research
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42
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Abstract
Sudden local chilling causes action currents to be set up in Nitella and in Chara, an effect which does not follow gradual local chilling. This may be due to a partial solidification of the non-aqueous protoplasmic surfaces which makes them susceptible to rupture by the protoplasmic streaming. This movement continues usually for several minutes after the chilling, whereas if stimulation occurs at all it occurs immediately on chilling. It is found that a chilled spot is much more sensitive to mechanical stimulation than is a spot at room temperature. Chilling is accompanied by a rise of resistance, a lowered rate of recovery following stimulation, and usually by a falling off in the magnitude of the action curve.
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Affiliation(s)
- S E Hill
- Laboratories of The Rockefeller Institute for Medical Research
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43
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Abstract
It is shown that the glass electrode may be used without appreciable error to measure pH of ammonia or ammonium chloride buffers, but that corrections must be applied above pH 8.6 if sodium ions are present in the unknown solution. Corrections are given for values from pH 8.6 to 9.4. A slight further modification of form of glass electrode used by previous workers is described.
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Affiliation(s)
- S E Hill
- Physiological Laboratory, Princeton University, Princeton
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Abstract
Cutting a cell of Nitella sets up a series of rapid electrical responses, transmitted at a rate too rapid to be measured by means of our records. These are followed by slower responses whose speed falls off as the distance from the cut increases, as though they were caused by a mechanical disturbance whose intensity falls off as it travels. The faster responses seem to be due to the motion of sap past protoplasmic surfaces which have suffered little or no alteration (they seem to be similar to the electrical changes following a blow on the end of a soft rubber tube containing Ag-AgCl electrodes). The slower responses appear to be due to alterations in the protoplasm and are usually irreversible.
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Affiliation(s)
- W J Osterhout
- Laboratories of The Rockefeller Institute for Medical Research
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Hill SE. THE PENETRATION OF LUMINOUS BACTERIA BY THE AMMONIUM SALTS OF THE LOWER FATTY ACIDS : PART I. GENERAL OUTLINE OF THE PROBLEM, AND THE EFFECTS OF STRONG ACIDS AND ALKALIES. ACTA ACUST UNITED AC 2010; 12:863-72. [PMID: 19872503 PMCID: PMC2323743 DOI: 10.1085/jgp.12.6.863] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
It is shown that disappearance of the light of luminous bacteria may be used as a criterion of cell penetration; that luminous bacteria are cytolyzed by water, hypotonic solutions, and by freely penetrating solutions; that luminous bacteria are not injured by hydrogen or hydroxyl ions in the external solutions within the range of pH values employed with the ammonium salts and that therefore disappearance of the light in isotonic solutions of these salts must be due to penetration of the solute; and that there is a characteristic difference between the effects of strong and of weak acids and alkalies on luminous bacteria.
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Affiliation(s)
- S E Hill
- Physiological Laboratory, Princeton University, Princeton
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46
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Abstract
Several forms of the action curve are described which might be accounted for on the ground that the outer protoplasmic surface shows no rapid electrical change. This may be due to the fact that the longitudinal flow of the outgoing current of action is in the protoplasm instead of in the cellulose wall. Hence the action curve has a short period with a single peak which does not reach zero. On this basis we can estimate the P.D. across the inner and outer protoplasmic surfaces separately. These P.D.'s can vary independently. In many cases there are successive action currents with incomplete recovery (with an increase or decrease or no change of magnitude). Some of the records resemble those obtained with nerve (including bursts of action currents and after-positivity).
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Affiliation(s)
- W J Osterhout
- Laboratories of The Rockefeller Institute for Medical Research
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47
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Abstract
Cells of Nitella have been studied which behave differently from those described in earlier papers. They show unexpectedly large changes in P.D. with certain concentrations of KCl. This is due to the production of action currents (these are recorded at the spot where KCl is applied). A method is given for the separate evaluation of changes of P.D. due to partition coefficients and those due to mobilities. A new amplifier and an improved flowing contact are described.
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Affiliation(s)
- S E Hill
- Laboratories of The Rockefeller Institute for Medical Research
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48
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Abstract
The action curve involves four movements each of which shows considerable variation. These variations can be accounted for on the assumption that the action curve is due to the movement of potassium ions accompanied by an increase in permeability.
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Affiliation(s)
- S E Hill
- Laboratories of The Rockefeller Institute for Medical Research
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49
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Abstract
A negative variation in Nitella is unable to pass a spot killed by chloroform but can set up a negative variation beyond this spot when a salt bridge is put around it. It can likewise set up a negative variation in a cell of another plant if connected to it by two salt bridges.
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Affiliation(s)
- W J Osterhout
- Laboratories of The Rockefeller Institute for Medical Research
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50
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Abstract
Mechanical stimulation of Nitella often produces responses resembling propagated negative variations but traveling faster and going past a killed spot. They appear to result from a mechanical disturbance traveling along the cell and stimulating each spot it touches (i.e. the stimulus itself travels). They are called mechanical variations to distinguish them from propagated negative variations. A mechanical disturbance may cause an irreversible change (death wave), but in traveling along the cell it may lose intensity and then produce only a reversible response (mechanical variation) which may eventually change to a propagated negative variation. The all or none law does not apply to incomplete mechanical variations, for the response varies with the strength of the stimulus.
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Affiliation(s)
- W J Osterhout
- Laboratories of The Rockefeller Institute for Medical Research
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