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Chen X, Fansler MM, Janjoš U, Ule J, Mayr C. The FXR1 network acts as signaling scaffold for actomyosin remodeling. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.11.05.565677. [PMID: 37961296 PMCID: PMC10635158 DOI: 10.1101/2023.11.05.565677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
It is currently not known whether mRNAs fulfill structural roles in the cytoplasm. Here, we report the FXR1 network, an mRNA-protein (mRNP) network present throughout the cytoplasm, formed by FXR1-mediated packaging of exceptionally long mRNAs. These mRNAs serve as underlying condensate scaffold and concentrate FXR1 molecules. The FXR1 network contains multiple protein binding sites and functions as a signaling scaffold for interacting proteins. We show that it is necessary for RhoA signaling-induced actomyosin reorganization to provide spatial proximity between kinases and their substrates. Point mutations in FXR1, found in its homolog FMR1, where they cause Fragile X syndrome, disrupt the network. FXR1 network disruption prevents actomyosin remodeling-an essential and ubiquitous process for the regulation of cell shape, migration, and synaptic function. These findings uncover a structural role for cytoplasmic mRNA and show how the FXR1 RNA-binding protein as part of the FXR1 network acts as organizer of signaling reactions.
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Affiliation(s)
- Xiuzhen Chen
- Cancer Biology and Genetics Program, Sloan Kettering Institute, New York, NY 10065, USA
| | - Mervin M Fansler
- Cancer Biology and Genetics Program, Sloan Kettering Institute, New York, NY 10065, USA
| | - Urška Janjoš
- National Institute of Chemistry, Hajdrihova 19, 1001 Ljubljana, Slovenia
- Biosciences PhD Program, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Jernej Ule
- National Institute of Chemistry, Hajdrihova 19, 1001 Ljubljana, Slovenia
- UK Dementia Research Institute at King's College London, London, SE5 9NU, UK
| | - Christine Mayr
- Cancer Biology and Genetics Program, Sloan Kettering Institute, New York, NY 10065, USA
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2
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Vaglietti S, Villeri V, Dell’Oca M, Marchetti C, Cesano F, Rizzo F, Miller D, LaPierre L, Pelassa I, Monje FJ, Colnaghi L, Ghirardi M, Fiumara F. PolyQ length-based molecular encoding of vocalization frequency in FOXP2. iScience 2023; 26:108036. [PMID: 37860754 PMCID: PMC10582585 DOI: 10.1016/j.isci.2023.108036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 07/18/2023] [Accepted: 09/21/2023] [Indexed: 10/21/2023] Open
Abstract
The transcription factor FOXP2, a regulator of vocalization- and speech/language-related phenotypes, contains two long polyQ repeats (Q1 and Q2) displaying marked, still enigmatic length variation across mammals. We found that the Q1/Q2 length ratio quantitatively encodes vocalization frequency ranges, from the infrasonic to the ultrasonic, displaying striking convergent evolution patterns. Thus, species emitting ultrasonic vocalizations converge with bats in having a low ratio, whereas species vocalizing in the low-frequency/infrasonic range converge with elephants and whales, which have higher ratios. Similar, taxon-specific patterns were observed for the FOXP2-related protein FOXP1. At the molecular level, we observed that the FOXP2 polyQ tracts form coiled coils, assembling into condensates and fibrils, and drive liquid-liquid phase separation (LLPS). By integrating evolutionary and molecular analyses, we found that polyQ length variation related to vocalization frequency impacts FOXP2 structure, LLPS, and transcriptional activity, thus defining a novel form of polyQ length-based molecular encoding of vocalization frequency.
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Affiliation(s)
- Serena Vaglietti
- Rita Levi Montalcini Department of Neuroscience, University of Turin, 10125 Turin, Italy
| | - Veronica Villeri
- Rita Levi Montalcini Department of Neuroscience, University of Turin, 10125 Turin, Italy
| | - Marco Dell’Oca
- Rita Levi Montalcini Department of Neuroscience, University of Turin, 10125 Turin, Italy
| | - Chiara Marchetti
- Rita Levi Montalcini Department of Neuroscience, University of Turin, 10125 Turin, Italy
| | - Federico Cesano
- Department of Chemistry, University of Turin, 10125 Turin, Italy
| | - Francesca Rizzo
- Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Kowloon Tong, Hong Kong SAR 518057, China
| | - Dave Miller
- Cascades Pika Watch, Oregon Zoo, Portland, OR 97221, USA
| | - Louis LaPierre
- Deptartment of Natural Science, Lower Columbia College, Longview, WA 98632, USA
| | - Ilaria Pelassa
- Rita Levi Montalcini Department of Neuroscience, University of Turin, 10125 Turin, Italy
| | - Francisco J. Monje
- Department of Neurophysiology and Neuropharmacology, Medical University of Vienna, 1090 Vienna, Austria
| | - Luca Colnaghi
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy
- School of Medicine, Vita-Salute San Raffaele University, 20132 Milan, Italy
| | - Mirella Ghirardi
- Rita Levi Montalcini Department of Neuroscience, University of Turin, 10125 Turin, Italy
| | - Ferdinando Fiumara
- Rita Levi Montalcini Department of Neuroscience, University of Turin, 10125 Turin, Italy
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3
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Tsai TY, Chen CY, Lin TW, Lin TC, Chiu FL, Shih O, Chang MY, Lin YC, Su AC, Chen CM, Jeng US, Kuo HC, Chang CF, Chen YR. Amyloid modifier SERF1a interacts with polyQ-expanded huntingtin-exon 1 via helical interactions and exacerbates polyQ-induced toxicity. Commun Biol 2023; 6:767. [PMID: 37479809 PMCID: PMC10361993 DOI: 10.1038/s42003-023-05142-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 07/13/2023] [Indexed: 07/23/2023] Open
Abstract
Abnormal polyglutamine (polyQ) expansion and fibrillization occur in Huntington's disease (HD). Amyloid modifier SERF enhances amyloid formation, but the underlying mechanism is not revealed. Here, the fibrillization and toxicity effect of SERF1a on Htt-exon1 are examined. SERF1a enhances the fibrillization of and interacts with mutant thioredoxin (Trx)-fused Httex1. NMR studies with Htt peptides show that TrxHttex1-39Q interacts with the helical regions in SERF1a and SERF1a preferentially interacts with the N-terminal 17 residues of Htt. Time-course analysis shows that SERF1a induces mutant TrxHttex1 to a single conformation enriched of β-sheet. Co-expression of SERF1a and Httex1-polyQ in neuroblastoma and lentiviral infection of SERF1a in HD-induced polypotent stem cell (iPSC)-derived neurons demonstrates the detrimental effect of SERF1a in HD. Higher level of SERF1a transcript or protein is detected in HD iPSC, transgenic mice, and HD plasma. Overall, this study provides molecular mechanism for SERF1a and mutant Httex1 to facilitate therapeutic development for HD.
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Affiliation(s)
- Tien-Ying Tsai
- Genomics Research Center, Academia Sinica, 128, Academia Rd., Sec. 2, Nankang District, Taipei, 115, Taiwan
- Chemical Biology and Molecular Biophysics Program, Taiwan International Graduate Program, Institute of Biological Chemistry, Academia Sinica, 128, Academia Road, Sec. 2. Nankang, Taipei, 115, Taiwan
- Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan
| | - Chun-Yu Chen
- Genomics Research Center, Academia Sinica, 128, Academia Rd., Sec. 2, Nankang District, Taipei, 115, Taiwan
| | - Tien-Wei Lin
- Genomics Research Center, Academia Sinica, 128, Academia Rd., Sec. 2, Nankang District, Taipei, 115, Taiwan
| | - Tien-Chang Lin
- National Synchrotron Radiation Research Center, Hsinchu, 300, Taiwan
- Department of Chemical Engineering, National Tsing Hua University, Hsinchu, 300, Taiwan
| | - Feng-Lan Chiu
- Institute of Cellular and Organismic Biology, Academia Sinica, 128, Academia Rd., Sec. 2, Nankang District, Taipei, 115, Taiwan
| | - Orion Shih
- National Synchrotron Radiation Research Center, Hsinchu, 300, Taiwan
| | - Ming-Yun Chang
- Genomics Research Center, Academia Sinica, 128, Academia Rd., Sec. 2, Nankang District, Taipei, 115, Taiwan
- Taiwan International Graduate Program in Interdisciplinary Neuroscience, National Yang Ming Chiao Tung University and Academia Sinica, Taipei, Taiwan
| | - Yu-Chun Lin
- Genomics Research Center, Academia Sinica, 128, Academia Rd., Sec. 2, Nankang District, Taipei, 115, Taiwan
| | - An-Chung Su
- Department of Chemical Engineering, National Tsing Hua University, Hsinchu, 300, Taiwan
| | - Chiung-Mei Chen
- Department of Neurology, Linkou Chang Gung Memorial Hospital and College of Medicine, Chang Gung University, Taoyuan, 333, Taiwan
| | - U-Ser Jeng
- National Synchrotron Radiation Research Center, Hsinchu, 300, Taiwan
- Department of Chemical Engineering, National Tsing Hua University, Hsinchu, 300, Taiwan
| | - Hung-Chih Kuo
- Institute of Cellular and Organismic Biology, Academia Sinica, 128, Academia Rd., Sec. 2, Nankang District, Taipei, 115, Taiwan
| | - Chi-Fon Chang
- Genomics Research Center, Academia Sinica, 128, Academia Rd., Sec. 2, Nankang District, Taipei, 115, Taiwan
| | - Yun-Ru Chen
- Genomics Research Center, Academia Sinica, 128, Academia Rd., Sec. 2, Nankang District, Taipei, 115, Taiwan.
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4
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Krawczyk HE, Sun S, Doner NM, Yan Q, Lim MSS, Scholz P, Niemeyer PW, Schmitt K, Valerius O, Pleskot R, Hillmer S, Braus GH, Wiermer M, Mullen RT, Ischebeck T. SEED LIPID DROPLET PROTEIN1, SEED LIPID DROPLET PROTEIN2, and LIPID DROPLET PLASMA MEMBRANE ADAPTOR mediate lipid droplet-plasma membrane tethering. THE PLANT CELL 2022; 34:2424-2448. [PMID: 35348751 PMCID: PMC9134073 DOI: 10.1093/plcell/koac095] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 02/14/2022] [Indexed: 05/27/2023]
Abstract
Membrane contact sites (MCSs) are interorganellar connections that allow for the direct exchange of molecules, such as lipids or Ca2+ between organelles, but can also serve to tether organelles at specific locations within cells. Here, we identified and characterized three proteins of Arabidopsis thaliana that form a lipid droplet (LD)-plasma membrane (PM) tethering complex in plant cells, namely LD-localized SEED LD PROTEIN (SLDP) 1 and SLDP2 and PM-localized LD-PLASMA MEMBRANE ADAPTOR (LIPA). Using proteomics and different protein-protein interaction assays, we show that both SLDPs associate with LIPA. Disruption of either SLDP1 and SLDP2 expression, or that of LIPA, leads to an aberrant clustering of LDs in Arabidopsis seedlings. Ectopic co-expression of one of the SLDPs with LIPA is sufficient to reconstitute LD-PM tethering in Nicotiana tabacum pollen tubes, a cell type characterized by dynamically moving LDs in the cytosolic streaming. Furthermore, confocal laser scanning microscopy revealed both SLDP2.1 and LIPA to be enriched at LD-PM contact sites in seedlings. These and other results suggest that SLDP and LIPA interact to form a tethering complex that anchors a subset of LDs to the PM during post-germinative seedling growth in Arabidopsis.
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Affiliation(s)
- Hannah Elisa Krawczyk
- Albrecht-von-Haller-Institute for Plant Sciences and Göttingen Center for Molecular Biosciences (GZMB), Department of Plant Biochemistry, University of Göttingen, Göttingen, Germany
| | - Siqi Sun
- Albrecht-von-Haller-Institute for Plant Sciences and Göttingen Center for Molecular Biosciences (GZMB), Department of Plant Biochemistry, University of Göttingen, Göttingen, Germany
| | - Nathan M Doner
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Qiqi Yan
- Albrecht-von-Haller-Institute for Plant Sciences and Göttingen Center for Molecular Biosciences (GZMB), Molecular Biology of Plant-Microbe Interactions Research Group, University of Göttingen, Göttingen, Germany
| | - Magdiel Sheng Satha Lim
- Albrecht-von-Haller-Institute for Plant Sciences and Göttingen Center for Molecular Biosciences (GZMB), Department of Plant Biochemistry, University of Göttingen, Göttingen, Germany
| | - Patricia Scholz
- Albrecht-von-Haller-Institute for Plant Sciences and Göttingen Center for Molecular Biosciences (GZMB), Department of Plant Biochemistry, University of Göttingen, Göttingen, Germany
| | - Philipp William Niemeyer
- Albrecht-von-Haller-Institute for Plant Sciences and Göttingen Center for Molecular Biosciences (GZMB), Department of Plant Biochemistry, University of Göttingen, Göttingen, Germany
| | - Kerstin Schmitt
- Institute for Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB) and Service Unit LCMS Protein Analytics, Department for Molecular Microbiology and Genetics, University of Göttingen, Göttingen, Germany
- Göttingen Center for Molecular Biosciences (GZMB), University of Göttingen, Göttingen, Germany
| | - Oliver Valerius
- Institute for Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB) and Service Unit LCMS Protein Analytics, Department for Molecular Microbiology and Genetics, University of Göttingen, Göttingen, Germany
- Göttingen Center for Molecular Biosciences (GZMB), University of Göttingen, Göttingen, Germany
| | - Roman Pleskot
- Institute of Experimental Botany of the Czech Academy of Sciences, Prague, Czech Republic
| | - Stefan Hillmer
- Electron Microscopy Core Facility, Heidelberg University, Heidelberg, Germany
| | - Gerhard H Braus
- Institute for Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB) and Service Unit LCMS Protein Analytics, Department for Molecular Microbiology and Genetics, University of Göttingen, Göttingen, Germany
- Göttingen Center for Molecular Biosciences (GZMB), University of Göttingen, Göttingen, Germany
| | - Marcel Wiermer
- Albrecht-von-Haller-Institute for Plant Sciences and Göttingen Center for Molecular Biosciences (GZMB), Molecular Biology of Plant-Microbe Interactions Research Group, University of Göttingen, Göttingen, Germany
- Göttingen Center for Molecular Biosciences (GZMB), University of Göttingen, Göttingen, Germany
| | - Robert T Mullen
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
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5
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Mórotz GM, Martín-Guerrero SM, Markovinovic A, Paillusson S, Russell MRG, Machado PMP, Fleck RA, Noble W, Miller CCJ. The PTPIP51 coiled-coil domain is important in VAPB binding, formation of ER-mitochondria contacts and IP3 receptor delivery of Ca 2+ to mitochondria. Front Cell Dev Biol 2022; 10:920947. [PMID: 36120587 PMCID: PMC9473665 DOI: 10.3389/fcell.2022.920947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Accepted: 06/29/2022] [Indexed: 11/23/2022] Open
Abstract
Signaling between the endoplasmic reticulum (ER) and mitochondria regulates a number of fundamental physiological processes. This signaling involves close physical contacts between the two organelles that are mediated by the VAPB-PTPIP51 ″tethering" proteins. The VAPB-PTPIP51 tethers facilitate inositol 1,4,5-trisphosphate (IP3) receptor delivery of Ca2+ from ER to mitochondria. Damage to the tethers is seen in Alzheimer's disease, Parkinson's disease and frontotemporal dementia with related amyotrophic lateral sclerosis (FTD/ALS). Understanding the mechanisms that regulate the VAPB-PTPIP51 interaction thus represents an important area of research. Recent studies suggest that an FFAT motif in PTPIP51 is key to its binding to VAPB but this work relies on in vitro studies with short peptides. Cellular studies to support this notion with full-length proteins are lacking. Here we address this issue. Immunoprecipitation assays from transfected cells revealed that deletion of the PTPIP51 FFAT motif has little effect on VAPB binding. However, mutation and deletion of a nearby coiled-coil domain markedly affect this binding. Using electron microscopy, we then show that deletion of the coiled-coil domain but not the FFAT motif abrogates the effect of PTPIP51 on ER-mitochondria contacts. Finally, we show that deletion of the coiled-coil domain but not the FFAT motif abrogates the effect of PTPIP51 on the IP3 receptor-mediated delivery of Ca2+ to mitochondria. Thus, the coiled-coil domain is essential for PTPIP51 ER-mitochondria signaling functions.
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Affiliation(s)
- Gábor M Mórotz
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, London, United Kingdom
| | - Sandra M Martín-Guerrero
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, London, United Kingdom
| | - Andrea Markovinovic
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, London, United Kingdom
| | - Sebastien Paillusson
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, London, United Kingdom
| | - Matthew R G Russell
- Centre for Ultrastructural Imaging, King's College London, London, United Kingdom
| | | | - Roland A Fleck
- Centre for Ultrastructural Imaging, King's College London, London, United Kingdom
| | - Wendy Noble
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, London, United Kingdom
| | - Christopher C J Miller
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, London, United Kingdom
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6
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The type 3 secretion system requires actin polymerization to open translocon pores. PLoS Pathog 2021; 17:e1009932. [PMID: 34499700 PMCID: PMC8454972 DOI: 10.1371/journal.ppat.1009932] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 09/21/2021] [Accepted: 08/31/2021] [Indexed: 11/19/2022] Open
Abstract
Many bacterial pathogens require a type 3 secretion system (T3SS) to establish a niche. Host contact activates bacterial T3SS assembly of a translocon pore in the host plasma membrane. Following pore formation, the T3SS docks onto the translocon pore. Docking establishes a continuous passage that enables the translocation of virulence proteins, effectors, into the host cytosol. Here we investigate the contribution of actin polymerization to T3SS-mediated translocation. Using the T3SS model organism Shigella flexneri, we show that actin polymerization is required for assembling the translocon pore in an open conformation, thereby enabling effector translocation. Opening of the pore channel is associated with a conformational change to the pore, which is dependent upon actin polymerization and a coiled-coil domain in the pore protein IpaC. Analysis of an IpaC mutant that is defective in ruffle formation shows that actin polymerization-dependent pore opening is distinct from the previously described actin polymerization-dependent ruffles that are required for bacterial internalization. Moreover, actin polymerization is not required for other pore functions, including docking or pore protein insertion into the plasma membrane. Thus, activation of the T3SS is a multilayered process in which host signals are sensed by the translocon pore leading to the activation of effector translocation.
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7
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Liu A, Kage F, Higgs HN. Mff oligomerization is required for Drp1 activation and synergy with actin filaments during mitochondrial division. Mol Biol Cell 2021; 32:ar5. [PMID: 34347505 PMCID: PMC8684745 DOI: 10.1091/mbc.e21-04-0224] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Mitochondrial division is an important cellular process in both normal and pathological conditions. The dynamin GTPase Drp1 is a central mitochondrial division protein, driving constriction of the outer mitochondrial membrane. In mammals, the outer mitochondrial membrane protein Mff is a key receptor for recruiting Drp1 from the cytosol to the mitochondrion. Actin filaments are also important in Drp1 recruitment and activation. The manner in which Mff and actin work together in Drp1 activation is unknown. Here, we show that Mff is an oligomer (most likely a trimer) that dynamically associates and disassociates through its C-terminal coiled-coil, with a Kd in the range of 10 µM. Dynamic Mff oligomerization is required for Drp1 activation. While not binding Mff directly, actin filaments enhance Mff-mediated Drp1 activation by lowering the effective Mff concentration 10-fold. Total internal reflection microscopy assays using purified proteins show that Mff interacts with Drp1 on actin filaments in a manner dependent on Mff oligomerization. In U2OS cells, oligomerization-defective Mff does not effectively rescue three defects in Mff knock-out cells: mitochondrial division, mitochondrial Drp1 recruitment, and peroxisome division. The ability of Mff to assemble into puncta on mitochondria depends on its oligomerization, as well as on actin filaments and Drp1.
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Affiliation(s)
- Ao Liu
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth College, Hanover NH 03755, USA
| | - Frieda Kage
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth College, Hanover NH 03755, USA
| | - Henry N Higgs
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth College, Hanover NH 03755, USA
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8
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Rahman SR, Cnaani J, Kinch LN, Grishin NV, Hines HM. A combined RAD-Seq and WGS approach reveals the genomic basis of yellow color variation in bumble bee Bombus terrestris. Sci Rep 2021; 11:7996. [PMID: 33846496 PMCID: PMC8042027 DOI: 10.1038/s41598-021-87194-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 03/22/2021] [Indexed: 12/30/2022] Open
Abstract
Bumble bees exhibit exceptional diversity in their segmental body coloration largely as a result of mimicry. In this study we sought to discover genes involved in this variation through studying a lab-generated mutant in bumble bee Bombus terrestris, in which the typical black coloration of the pleuron, scutellum, and first metasomal tergite is replaced by yellow, a color variant also found in sister lineages to B. terrestris. Utilizing a combination of RAD-Seq and whole-genome re-sequencing, we localized the color-generating variant to a single SNP in the protein-coding sequence of transcription factor cut. This mutation generates an amino acid change that modifies the conformation of a coiled-coil structure outside DNA-binding domains. We found that all sequenced Hymenoptera, including sister lineages, possess the non-mutant allele, indicating different mechanisms are involved in the same color transition in nature. Cut is important for multiple facets of development, yet this mutation generated no noticeable external phenotypic effects outside of setal characteristics. Reproductive capacity was reduced, however, as queens were less likely to mate and produce female offspring, exhibiting behavior similar to that of workers. Our research implicates a novel developmental player in pigmentation, and potentially caste, thus contributing to a better understanding of the evolution of diversity in both of these processes.
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Affiliation(s)
- Sarthok Rasique Rahman
- Department of Biology, The Pennsylvania State University, 208 Mueller Labs, University Park, PA, USA
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL, 35487, USA
| | | | - Lisa N Kinch
- Howard Hughes Medical Institute and Departments of Biophysics and Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Nick V Grishin
- Howard Hughes Medical Institute and Departments of Biophysics and Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Heather M Hines
- Department of Biology, The Pennsylvania State University, 208 Mueller Labs, University Park, PA, USA.
- Department of Entomology, The Pennsylvania State University, University Park, PA, USA.
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9
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MED15 prion-like domain forms a coiled-coil responsible for its amyloid conversion and propagation. Commun Biol 2021; 4:414. [PMID: 33772081 PMCID: PMC7997880 DOI: 10.1038/s42003-021-01930-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 03/02/2021] [Indexed: 02/01/2023] Open
Abstract
A disordered to β-sheet transition was thought to drive the functional switch of Q/N-rich prions, similar to pathogenic amyloids. However, recent evidence indicates a critical role for coiled-coil (CC) regions within yeast prion domains in amyloid formation. We show that many human prion-like domains (PrLDs) contain CC regions that overlap with polyQ tracts. Most of the proteins bearing these domains are transcriptional coactivators, including the Mediator complex subunit 15 (MED15) involved in bridging enhancers and promoters. We demonstrate that the human MED15-PrLD forms homodimers in solution sustained by CC interactions and that it is this CC fold that mediates the transition towards a β-sheet amyloid state, its chemical or genetic disruption abolishing aggregation. As in functional yeast prions, a GFP globular domain adjacent to MED15-PrLD retains its structural integrity in the amyloid state. Expression of MED15-PrLD in human cells promotes the formation of cytoplasmic and perinuclear inclusions, kidnapping endogenous full-length MED15 to these aggregates in a prion-like manner. The prion-like properties of MED15 are conserved, suggesting novel mechanisms for the function and malfunction of this transcription coactivator.
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10
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Design and structural characterisation of monomeric water-soluble α-helix and β-hairpin peptides: State-of-the-art. Arch Biochem Biophys 2019; 661:149-167. [DOI: 10.1016/j.abb.2018.11.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 11/06/2018] [Accepted: 11/14/2018] [Indexed: 02/06/2023]
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11
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Verhoork SJM, Killoran PM, Coxon CR. Fluorinated Prolines as Conformational Tools and Reporters for Peptide and Protein Chemistry. Biochemistry 2018; 57:6132-6143. [DOI: 10.1021/acs.biochem.8b00787] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Sanne J. M. Verhoork
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Byrom Street Campus, Liverpool L3 3AF, U.K
| | - Patrick M. Killoran
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Byrom Street Campus, Liverpool L3 3AF, U.K
| | - Christopher R. Coxon
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Byrom Street Campus, Liverpool L3 3AF, U.K
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12
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Nogueira GAS, Costa EFD, Lopes-Aguiar L, Lima TRP, Visacri MB, Pincinato EC, Lourenço GJ, Calonga L, Mariano FV, Altemani AMDAM, Altemani JMC, Moriel P, Chone CT, Ramos CD, Lima CSP. Polymorphisms in DNA mismatch repair pathway genes predict toxicity and response to cisplatin chemoradiation in head and neck squamous cell carcinoma patients. Oncotarget 2018; 9:29538-29547. [PMID: 30038702 PMCID: PMC6049861 DOI: 10.18632/oncotarget.25268] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2018] [Accepted: 03/26/2018] [Indexed: 12/27/2022] Open
Abstract
Head and neck squamous cell carcinoma (HNSCC) is treated with cisplatin (CDDP) and radiotherapy (RT), and distinct results are observed among patients with similar clinicopathological aspects. This prospective study aimed to investigate whether MLH1 c.-93G>A (rs1800734), MSH2 c.211+9C>G (rs2303426), MSH3 c.3133G>A (rs26279), EXO1 c.1765G>A (rs1047840), and EXO1 c.2270C>T (rs9350) single nucleotide polymorphisms (SNPs) of the mismatch repair (MMR) pathway change side effects and response rate of 90 HNSCC patients treated with CDDP and RT. DNA from peripheral blood was analyzed by PCR-based methods to obtain genotypes. It was observed 4.27-fold and 4.69-fold increased risks of presenting pronounced nephrotoxicity with treatment in patients with MSH3 GG and EXO1 rs9350 CC genotypes compared with patients with GA or AA and CT or TT genotypes, respectively. MSH3 GG or GA and GT haplotype of EXO1 rs1047840 and rs9350 SNPs conferred to patients 10.29 and 4.00 more chances of presenting pronounced ototoxicity after treatment than MSH3 AA genotype and other EXO1 haplotypes, respectively. Patients with EXO1 rs1047840 GA or AA genotype and AC haplotype of EXO1 rs1047840 and rs9350 SNPs had both 9.55-fold increased risks of achieving partial response or stable disease instead of complete remission after treatment than patients with EXO1 GG genotype and other EXO1 haplotypes, respectively. For the first time, our data show preliminary indication that inherited alterations of DNA MMR pathway, related to MSH3 rs26279, EXO1 rs1047840 and EXO1 rs9350 SNPs, modify toxicity and response to chemoradiation in HNSCC, and may contribute to future personalized treatment of patients.
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Affiliation(s)
| | | | - Leisa Lopes-Aguiar
- Department of Internal Medicine, Faculty of Medical Sciences, University of Campinas, Campinas, São Paulo, Brazil
| | - Tathiane Regine Penna Lima
- Department of Internal Medicine, Faculty of Medical Sciences, University of Campinas, Campinas, São Paulo, Brazil
| | - Marília Berlofa Visacri
- Department of Clinical Pathology, Faculty of Medical Sciences, University of Campinas, Campinas, São Paulo, Brazil
| | - Eder Carvalho Pincinato
- Department of Internal Medicine, Faculty of Medical Sciences, University of Campinas, Campinas, São Paulo, Brazil
| | - Gustavo Jacob Lourenço
- Laboratory of Cancer Genetics, Faculty of Medical Sciences, University of Campinas, Campinas, São Paulo, Brazil
| | - Luciane Calonga
- Department of Ophthalmology and Otorhinolaryngology, Faculty of Medical Sciences, University of Campinas, Campinas, São Paulo, Brazil
| | - Fernanda Viviane Mariano
- Department of Pathology, Faculty of Medical Sciences, University of Campinas, Campinas, São Paulo, Brazil
| | | | | | - Patrícia Moriel
- Department of Clinical Pathology, Faculty of Medical Sciences, University of Campinas, Campinas, São Paulo, Brazil
| | - Carlos Takahiro Chone
- Department of Ophthalmology and Otorhinolaryngology, Faculty of Medical Sciences, University of Campinas, Campinas, São Paulo, Brazil
| | - Celso Dario Ramos
- Department of Radiology, Faculty of Medical Sciences, University of Campinas, Campinas, São Paulo, Brazil
| | - Carmen Silvia Passos Lima
- Department of Internal Medicine, Faculty of Medical Sciences, University of Campinas, Campinas, São Paulo, Brazil
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Martinez D, Legrand A, Gronnier J, Decossas M, Gouguet P, Lambert O, Berbon M, Verron L, Grélard A, Germain V, Loquet A, Mongrand S, Habenstein B. Coiled-coil oligomerization controls localization of the plasma membrane REMORINs. J Struct Biol 2018; 206:12-19. [PMID: 29481850 DOI: 10.1016/j.jsb.2018.02.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2017] [Revised: 01/25/2018] [Accepted: 02/12/2018] [Indexed: 12/20/2022]
Abstract
REMORINs are nanodomain-organized proteins located in the plasma membrane and involved in cellular responses in plants. The dynamic assembly of the membrane nanodomains represents an essential tool of the versatile membrane barriers to control and modulate cellular functions. Nevertheless, the assembly mechanisms and protein organization strategies of nanodomains are poorly understood and many structural aspects are difficult to visualize. Using an ensemble of biophysical approaches, including solid-state nuclear magnetic resonance, cryo-electron microscopy and in vivo confocal imaging, we provide first insights on the role and the structural mechanisms of REMORIN trimerization. Our results suggest that the formation of REMORIN coiled-coil trimers is essential for membrane recruitment and promotes REMORIN assembly in vitro into long filaments by trimer-trimer interactions that might participate in nanoclustering into membrane domains in vivo.
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Affiliation(s)
- Denis Martinez
- Institute of Chemistry & Biology of Membranes & Nanoobjects (UMR5248 CBMN), IECB, CNRS, Universite Bordeaux, Institut Polytechnique Bordeaux, All. Geoffroy Saint-Hilaire, 33600 Pessac, France
| | - Anthony Legrand
- Institute of Chemistry & Biology of Membranes & Nanoobjects (UMR5248 CBMN), IECB, CNRS, Universite Bordeaux, Institut Polytechnique Bordeaux, All. Geoffroy Saint-Hilaire, 33600 Pessac, France
| | - Julien Gronnier
- Laboratoire de Biogènese Membranaire - UMR 5200 - CNRS, Université de Bordeaux, 71 Avenue Edouard Bourlaux, 33883 Villenave d'Ornon Cédex, France
| | - Marion Decossas
- Institute of Chemistry & Biology of Membranes & Nanoobjects (UMR5248 CBMN), CNRS, Universite Bordeaux, Institut Polytechnique Bordeaux, 14 All. Geoffroy Saint-Hilaire, 33600 Pessac, France
| | - Paul Gouguet
- Laboratoire de Biogènese Membranaire - UMR 5200 - CNRS, Université de Bordeaux, 71 Avenue Edouard Bourlaux, 33883 Villenave d'Ornon Cédex, France
| | - Olivier Lambert
- Institute of Chemistry & Biology of Membranes & Nanoobjects (UMR5248 CBMN), CNRS, Universite Bordeaux, Institut Polytechnique Bordeaux, 14 All. Geoffroy Saint-Hilaire, 33600 Pessac, France
| | - Mélanie Berbon
- Institute of Chemistry & Biology of Membranes & Nanoobjects (UMR5248 CBMN), IECB, CNRS, Universite Bordeaux, Institut Polytechnique Bordeaux, All. Geoffroy Saint-Hilaire, 33600 Pessac, France
| | - Loris Verron
- Institute of Chemistry & Biology of Membranes & Nanoobjects (UMR5248 CBMN), IECB, CNRS, Universite Bordeaux, Institut Polytechnique Bordeaux, All. Geoffroy Saint-Hilaire, 33600 Pessac, France
| | - Axelle Grélard
- Institute of Chemistry & Biology of Membranes & Nanoobjects (UMR5248 CBMN), IECB, CNRS, Universite Bordeaux, Institut Polytechnique Bordeaux, All. Geoffroy Saint-Hilaire, 33600 Pessac, France
| | - Veronique Germain
- Laboratoire de Biogènese Membranaire - UMR 5200 - CNRS, Université de Bordeaux, 71 Avenue Edouard Bourlaux, 33883 Villenave d'Ornon Cédex, France
| | - Antoine Loquet
- Institute of Chemistry & Biology of Membranes & Nanoobjects (UMR5248 CBMN), IECB, CNRS, Universite Bordeaux, Institut Polytechnique Bordeaux, All. Geoffroy Saint-Hilaire, 33600 Pessac, France.
| | - Sébastien Mongrand
- Laboratoire de Biogènese Membranaire - UMR 5200 - CNRS, Université de Bordeaux, 71 Avenue Edouard Bourlaux, 33883 Villenave d'Ornon Cédex, France.
| | - Birgit Habenstein
- Institute of Chemistry & Biology of Membranes & Nanoobjects (UMR5248 CBMN), IECB, CNRS, Universite Bordeaux, Institut Polytechnique Bordeaux, All. Geoffroy Saint-Hilaire, 33600 Pessac, France.
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Kraatz S, Guichard P, Obbineni JM, Olieric N, Hatzopoulos GN, Hilbert M, Sen I, Missimer J, Gönczy P, Steinmetz MO. The Human Centriolar Protein CEP135 Contains a Two-Stranded Coiled-Coil Domain Critical for Microtubule Binding. Structure 2016; 24:1358-1371. [PMID: 27477386 DOI: 10.1016/j.str.2016.06.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Revised: 06/07/2016] [Accepted: 06/10/2016] [Indexed: 11/24/2022]
Abstract
Centrioles are microtubule-based structures that play important roles notably in cell division and cilium biogenesis. CEP135/Bld10p family members are evolutionarily conserved microtubule-binding proteins important for centriole formation. Here, we analyzed in detail the microtubule-binding activity of human CEP135 (HsCEP135). X-ray crystallography and small-angle X-ray scattering in combination with molecular modeling revealed that the 158 N-terminal residues of HsCEP135 (HsCEP135-N) form a parallel two-stranded coiled-coil structure. Biochemical, cryo-electron, and fluorescence microscopy analyses revealed that in vitro HsCEP135-N interacts with tubulin, protofilaments, and microtubules and induces the formation of microtubule bundles. We further identified a 13 amino acid segment spanning residues 96-108, which represents a major microtubule-binding site in HsCEP135-N. Within this segment, we identified a cluster of three lysine residues that contribute to the microtubule bundling activity of HsCEP135-N. Our results provide the first structural information on CEP135/Bld10p proteins and offer insights into their microtubule-binding mechanism.
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Affiliation(s)
- Sebastian Kraatz
- Laboratory of Biomolecular Research, Department of Biology and Chemistry, Paul Scherrer Institut, 5232 Villigen, Switzerland
| | - Paul Guichard
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland
| | - Jagan M Obbineni
- Laboratory of Biomolecular Research, Department of Biology and Chemistry, Paul Scherrer Institut, 5232 Villigen, Switzerland
| | - Natacha Olieric
- Laboratory of Biomolecular Research, Department of Biology and Chemistry, Paul Scherrer Institut, 5232 Villigen, Switzerland
| | - Georgios N Hatzopoulos
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland
| | - Manuel Hilbert
- Laboratory of Biomolecular Research, Department of Biology and Chemistry, Paul Scherrer Institut, 5232 Villigen, Switzerland
| | - Indrani Sen
- Laboratory of Biomolecular Research, Department of Biology and Chemistry, Paul Scherrer Institut, 5232 Villigen, Switzerland
| | - John Missimer
- Laboratory of Biomolecular Research, Department of Biology and Chemistry, Paul Scherrer Institut, 5232 Villigen, Switzerland
| | - Pierre Gönczy
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland
| | - Michel O Steinmetz
- Laboratory of Biomolecular Research, Department of Biology and Chemistry, Paul Scherrer Institut, 5232 Villigen, Switzerland.
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Cheng SF, Sung TC, Chang CC, Chou MJ, Chiang YW, Chang DK. Kinetics study on the HIV-1 ectodomain protein quaternary structure formation reveals coupling of chain folding and self-assembly in the refolding cascade. J Phys Chem B 2014; 118:12827-36. [PMID: 25333416 DOI: 10.1021/jp508360k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Entry of HIV-1 into the target cell is mediated by the envelope glycoprotein consisting of noncovalently associated surface subunit gp120 and transmembrane subunit gp41. To form a functional gp41 complex, the protein undergoes hairpin formation and self-assembly. The fusion event can be inhibited by gp41-derived peptides at nanomolar concentration and is highly dependent on the time of addition, implying a role of folding kinetics on the inhibitory action. Oligomerization of the gp41 ectodomain was demonstrated by light scattering measurements. Kinetic study by stopped-flow fluorescence and absorption measurements (i) revealed a multistate folding pathway and stable intermediates; (ii) showed a dissection of fast and slow components for early and late stages of folding, respectively, with 3 orders of magnitude difference in the time scale; (iii) showed the slow process was attributed to misfolding and unzipping of the hairpin; and (iv) showed retardation of the native hairpin formation is assumed to lead to coupling of the correctly registered hairpin and self-assembly. This coupling allows the deduction on the time scale of intrachain folding (0.1-1 s) for the protein. The folding reaction was illustrated by a free energy profile to explain the temporal dichotomy of fast and slow steps of folding as well as effective inhibition by gp41-derived peptide.
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Affiliation(s)
- Shu-Fang Cheng
- Institute of Chemistry, Academia Sinica , Taipei, Taiwan, Republic of China 11529
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16
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Abstract
Recent studies have elucidated key principles governing folding and stability of α-helices in short peptides and globular proteins. In this chapter we review briefly those principles and describe a protocol for the de novo design of highly stable α-helixes using the SEQOPT algorithm. This algorithm is based on AGADIR, the statistical mechanical theory for helix-coil transitions in monomeric peptides, and the tunneling algorithm for global sequence optimization.
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18
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Lemmin T, Soto CS, Clinthorne G, DeGrado WF, Dal Peraro M. Assembly of the transmembrane domain of E. coli PhoQ histidine kinase: implications for signal transduction from molecular simulations. PLoS Comput Biol 2013; 9:e1002878. [PMID: 23359663 PMCID: PMC3554529 DOI: 10.1371/journal.pcbi.1002878] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 11/17/2012] [Indexed: 01/26/2023] Open
Abstract
The PhoQP two-component system is a signaling complex essential for bacterial virulence and cationic antimicrobial peptide resistance. PhoQ is the histidine kinase chemoreceptor of this tandem machine and assembles in a homodimer conformation spanning the bacterial inner membrane. Currently, a full understanding of the PhoQ signal transduction is hindered by the lack of a complete atomistic structure. In this study, an atomistic model of the key transmembrane (TM) domain is assembled by using molecular simulations, guided by experimental cross-linking data. The formation of a polar pocket involving Asn202 in the lumen of the tetrameric TM bundle is crucial for the assembly and solvation of the domain. Moreover, a concerted displacement of the TM helices at the periplasmic side is found to modulate a rotation at the cytoplasmic end, supporting the transduction of the chemical signal through a combination of scissoring and rotational movement of the TM helices. Two-component systems (TCSs) are signaling complexes essential for bacterial survival and virulence. PhoQ is the histidine kinase chemoreceptor of the PhoQ-PhoP tandem machine that detects the concentration of cationic species at the inner membrane of Gram-negative bacteria. A full understanding of the PhoQ signal transduction mechanism is currently hindered by the lack of a complete atomistic structure. Here, by using molecular simulations integrated with cross-linking disulfide scanning data, we present the first structural model of the transmembrane (TM) portion of PhoQ from E. coli. Its structural and dynamic features induce a concerted displacement of the TM helices at the periplasmic side, which modulates a rotation at the cytoplasmic end. This supports the idea that signal transduction is promoted through a combination of scissoring and rotational movements of the TM helices. This complex mechanism is the key to understanding how the chemical stimuli sensed by the periplasmic sensor domain trigger, via the relay of the HAMP domain, the histidine auto-phosphorylation and kinase/phosphatase activity at the cytoplasmic end.
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Affiliation(s)
- Thomas Lemmin
- Laboratory for Biomolecular Modeling, Institute of Bioengineering, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Cinque S. Soto
- Department of Biochemistry and Biophysics, University of Pennsylvania, School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Graham Clinthorne
- Department of Biochemistry and Biophysics, University of Pennsylvania, School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - William F. DeGrado
- Department of Pharmaceutical Chemistry, University of California – San Francisco, San Francisco, California, United States of America
| | - Matteo Dal Peraro
- Laboratory for Biomolecular Modeling, Institute of Bioengineering, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
- * E-mail:
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19
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Efficacy verification and microscopic observations of an anticancer peptide, CB1a, on single lung cancer cell. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1818:2927-35. [PMID: 22846508 DOI: 10.1016/j.bbamem.2012.07.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2012] [Revised: 07/20/2012] [Accepted: 07/23/2012] [Indexed: 02/05/2023]
Abstract
In this work, we introduce a new customized anti-lung cancer peptide, CB1a, with IC₅₀ of about 25.0 ± 1.6 μM on NCI-H460 lung cancer cells. Using a multi-cellular tumor spheroid (MCTS) model, results show that CB1a is potent in preventing the growth of lung cancer tumor-like growths in vitro. Additionally, atomic force microscopy (AFM) was used to examine cell surface damage of a single cancer. The mechanism for cell death under CB1a toxicity was verified as being largely due to cell surface damage. Moreover, with a treatment dosage of CB1a at 25 μM, Young's module (E) shows that the elasticity and stiffness of cancer cell decreased with time such that the interaction time for a 50% reduction of E (IT₅₀) was about 7.0min. This new single-cell toxicity investigation using IT₅₀ under AFM assay can be used to separately verify drug efficacy in support of the traditional IC₅₀ measurement in bulk solution. These results could be of special interest to researchers engaged in new drug development.
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20
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Abnormal actin binding of aberrant β-tropomyosins is a molecular cause of muscle weakness in TPM2-related nemaline and cap myopathy. Biochem J 2012; 442:231-9. [PMID: 22084935 DOI: 10.1042/bj20111030] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
NM (nemaline myopathy) is a rare genetic muscle disorder defined on the basis of muscle weakness and the presence of structural abnormalities in the muscle fibres, i.e. nemaline bodies. The related disorder cap myopathy is defined by cap-like structures located peripherally in the muscle fibres. Both disorders may be caused by mutations in the TPM2 gene encoding β-Tm (tropomyosin). Tm controls muscle contraction by inhibiting actin-myosin interaction in a calcium-sensitive manner. In the present study, we have investigated the pathogenetic mechanisms underlying five disease-causing mutations in Tm. We show that four of the mutations cause changes in affinity for actin, which may cause muscle weakness in these patients, whereas two show defective Ca2+ activation of contractility. We have also mapped the amino acids altered by the mutation to regions important for actin binding and note that two of the mutations cause altered protein conformation, which could account for impaired actin affinity.
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21
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Palmitoylated calnexin is a key component of the ribosome-translocon complex. EMBO J 2012; 31:1823-35. [PMID: 22314232 DOI: 10.1038/emboj.2012.15] [Citation(s) in RCA: 132] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2011] [Accepted: 01/03/2012] [Indexed: 12/11/2022] Open
Abstract
A third of the human genome encodes N-glycosylated proteins. These are co-translationally translocated into the lumen/membrane of the endoplasmic reticulum (ER) where they fold and assemble before they are transported to their final destination. Here, we show that calnexin, a major ER chaperone involved in glycoprotein folding is palmitoylated and that this modification is mediated by the ER palmitoyltransferase DHHC6. This modification leads to the preferential localization of calnexin to the perinuclear rough ER, at the expense of ER tubules. Moreover, palmitoylation mediates the association of calnexin with the ribosome-translocon complex (RTC) leading to the formation of a supercomplex that recruits the actin cytoskeleton, leading to further stabilization of the assembly. When formation of the calnexin-RTC supercomplex was affected by DHHC6 silencing, mutation of calnexin palmitoylation sites or actin depolymerization, folding of glycoproteins was impaired. Our findings thus show that calnexin is a stable component of the RTC in a manner that is exquisitely dependent on its palmitoylation status. This association is essential for the chaperone to capture its client proteins as they emerge from the translocon, acquire their N-linked glycans and initiate folding.
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Chang CC, Cheng SF, Lin CH, Chen SSL, Chang DK. Stability of gp41 hairpin and helix bundle assembly probed by combined stacking and circular dichroic approaches. J Struct Biol 2011; 175:406-14. [DOI: 10.1016/j.jsb.2011.06.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2011] [Revised: 05/17/2011] [Accepted: 06/16/2011] [Indexed: 10/18/2022]
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Ah Mew N, Caldovic L. N-acetylglutamate synthase deficiency: an insight into the genetics, epidemiology, pathophysiology, and treatment. APPLICATION OF CLINICAL GENETICS 2011; 4:127-35. [PMID: 23776373 PMCID: PMC3681184 DOI: 10.2147/tacg.s12702] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The conversion of ammonia into urea by the human liver requires the coordinated function of the 6 enzymes and 2 transporters of the urea cycle. The initial and rate-limiting enzyme of the urea cycle, carbamylphosphate synthetase 1 (CPS1), requires an allosteric activator, N-acetylglutamate (NAG). The formation of this unique cofactor from glutamate and acetyl Coenzyme-A is catalyzed by N-acetylglutamate synthase (NAGS). An absence of NAG as a consequence of NAGS deficiency may compromise flux through CPS1 and result in hyperammonemia. The NAGS gene encodes a 528-amino acid protein, consisting of a C-terminal catalytic domain, a variable segment, and an N-terminal mitochondrial targeting signal. Only 22 mutations in the NAGS gene have been reported to date, mostly in the catalytic domain. NAGS is primarily expressed in the liver and intestine. However, it is also surprisingly expressed in testis, stomach and spleen, and during early embryonic development at levels not concordant with the expression of other urea cycle enzymes, CPS1, or ornithine transcarbamylase. The purpose of NAGS expression in these tissues, and its significance to NAGS deficiency is as yet unknown. Inherited NAGS deficiency is the rarest of the urea cycle disorders, and we review the currently reported 34 cases. Treatment of NAGS deficiency with N-carbamyglutamate, a stable analog of NAG, can restore deficient urea cycle function and normalize blood ammonia in affected patients.
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Affiliation(s)
- Nicholas Ah Mew
- Center for Genetic Medicine Research, Children's Research institute, Children's National Medical Center, Washington DC, USA
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Fiumara F, Fioriti L, Kandel ER, Hendrickson WA. Essential role of coiled coils for aggregation and activity of Q/N-rich prions and PolyQ proteins. Cell 2011; 143:1121-35. [PMID: 21183075 DOI: 10.1016/j.cell.2010.11.042] [Citation(s) in RCA: 192] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Revised: 08/23/2010] [Accepted: 11/16/2010] [Indexed: 11/19/2022]
Abstract
The functional switch of glutamine/asparagine (Q/N)-rich prions and the neurotoxicity of polyQ-expanded proteins involve complex aggregation-prone structural transitions, commonly presumed to be forming β sheets. By analyzing sequences of interaction partners of these proteins, we discovered a recurrent presence of coiled-coil domains both in the partners and in segments that flank or overlap Q/N-rich and polyQ domains. Since coiled coils can mediate protein interactions and multimerization, we studied their possible involvement in Q/N-rich and polyQ aggregations. Using circular dichroism and chemical crosslinking, we found that Q/N-rich and polyQ peptides form α-helical coiled coils in vitro and assemble into multimers. Using structure-guided mutagenesis, we found that coiled-coil domains modulate in vivo properties of two Q/N-rich prions and polyQ-expanded huntingtin. Mutations that disrupt coiled coils impair aggregation and activity, whereas mutations that enhance coiled-coil propensity promote aggregation. These findings support a coiled-coil model for the functional switch of Q/N-rich prions and for the pathogenesis of polyQ-expansion diseases.
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Affiliation(s)
- Ferdinando Fiumara
- Department of Neuroscience, Columbia University, New York, NY 10032, USA
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25
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Haghighi MM, Taleghani MY, Mohebbi SR, Vahedi M, Fatemi SR, Zali N, Shemirani AI, Zali MR. Impact of EXO1 polymorphism in susceptibility to colorectal cancer. Genet Test Mol Biomarkers 2010; 14:649-52. [PMID: 20854105 DOI: 10.1089/gtmb.2010.0034] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND AND AIM One candidate gene for colorectal cancer (CRC) susceptibility is exonuclease 1 (EXO1). It is a member of RAD2 nuclease family, which plays a major role in mismatch repair, DNA replication, and recombination. Single-nucleotide polymorphisms are shown to be related with cancer incidence. The aim of the present study was to examine the association between the L757P polymorphism at exon 13 of the EXO1 gene and the risk of CRC in Iranian patients. METHODS In this case-control study, 90 cases and 98 healthy control samples were analyzed genetically. The EXO1 polymorphism, P757L, was analyzed by polymerase chain reaction-restriction fragment length polymorphism. The obtained polymorphisms were examined for the relationship with CRC risk and also clinicopathological characteristics. RESULTS Our findings showed that patients with the Leu/Leu genotype have a reduced risk of CRC (adjusted odds ratio [OR] = 0.192, 95% confidence interval [CI]: 0.040-0.921) when the Pro/Leu and Pro/Pro genotypes were blended and they were considered as the reference. The Leu/Leu genotype also showed a reduced risk (adjusted OR = 0.168, 95% CI: 0.034-0.816) when the Pro/Pro genotype was a reference; nevertheless, the Pro/Leu genotype did not reveal a significant association with CRC at the same status (adjusted OR = 0.686, 95% CI: 0.367-1.284). CONCLUSIONS Our results provide evidence diagnosing that the Leu/Leu genotype of EXO1 showed an inverse association with CRC. In addition, despite other investigations, we could define a significant association between the Leu allele and CRC (p = 0.001).
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Affiliation(s)
- Mahdi Montazer Haghighi
- Research Center for Gastroenterology and Liver Diseases, Taleghani Hospital, Shaheed Beheshti Medical University, Tehran, Iran.
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Wu JM, Jan PS, Yu HC, Haung HY, Fang HJ, Chang YI, Cheng JW, Chen HM. Structure and function of a custom anticancer peptide, CB1a. Peptides 2009; 30:839-48. [PMID: 19428759 DOI: 10.1016/j.peptides.2009.02.004] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2008] [Revised: 02/02/2009] [Accepted: 02/03/2009] [Indexed: 12/01/2022]
Abstract
Several natural antimicrobial peptides including cecropins, magainins and melittins have been found to kill cancer cells. However, their efficacy may not be adequate for their development as anticancer agents. In this study, we used a natural antimicrobial peptide, cecropin B (CB), as a template to generate a novel anticancer peptide. Cecropin B is an amphipathic and polycationic peptide derived from the hemolymph of Hyalophora cecropia with well-known antimicrobial and cytolytic properties. The signature pattern of cecropins is W-x-(0,2)-[KDN]-x-{L}-K-[KRE]-[LI]-E-[RKN] (PROSITE: PS00268), and this signature sequence is located at N-terminus of CB. CB1a was constructed by repeating the N-terminal ten amino acids of CB three times and including a hinge near C-terminus. The circular dichroism spectra showed that CB1a is unstructured in aqueous solution, but adopt a helical conformation in membrane-like environment. The solution structure of CB1a in a polar solvent was also studied by NMR. CB1a formed a helix-hinge-helix in 20% HFIP solution, and it was found the bent angle between two helical segments was induced ranging from 60 degrees to 110 degrees . A heparin-binding motif is located in the central part of helix 1. Isothermal titration calorimetry reveals the association constant of CB1a bound to low molecular weight heparin is 1.66 x 10(5)M(-1) at physiological ionic strength at 25 degrees C. Binding of CB1a to heparin produces a large conformational change toward a more structural state. CB1a demonstrated promising activity against several cancer cells but low toxicity against non-cancer cells. The IC(50) of CB1a on leukemia and stomach carcinoma cells were in the range of 2-8-fold lower than those of CB. Besides, CB1a exhibited low hemolytic activity against human red blood cells. Due to these properties, CB1a has the potential to become a promising anticancer agent.
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Affiliation(s)
- Jiun-Ming Wu
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan
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Lin CH, Chang CC, Cheng SF, Chang DK. The application of perfluorooctanoate to investigate trimerization of the human immunodeficiency virus-1 gp41 ectodomain by electrophoresis. Electrophoresis 2008; 29:3175-82. [DOI: 10.1002/elps.200700863] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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29
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Influence of proline on the thermostability of the active site and membrane arrangement of transmembrane proteins. Biophys J 2008; 95:4384-95. [PMID: 18658225 DOI: 10.1529/biophysj.108.136747] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Proline residues play a fundamental and subtle role in the dynamics, structure, and function in many membrane proteins. Temperature derivative spectroscopy and differential scanning calorimetry have been used to determine the effect of proline substitution in the structural stability of the active site and transmembrane arrangement of bacteriorhodopsin. We have analyzed the Pro-to-Ala mutation for the helix-embedded prolines Pro50, Pro91, and Pro186 in the native membrane environment. This information has been complemented with the analysis of the respective crystallographic structures by the FoldX force field. Differential scanning calorimetry allowed us to determine distorted membrane arrangement for P50A and P186A. The protein stability was severely affected for P186A and P91A. In the case of Pro91, a single point mutation is capable of strongly slowing down the conformational diffusion along the denaturation coordinate, becoming a barrier-free downhill process above 371 K. Temperature derivative spectroscopy, applied for first time to study thermal stability of proteins, has been used to monitor the stability of the active site of bacteriorhodopsin. The mutation of Pro91 and Pro186 showed the most striking effects on the retinal binding pocket. These residues are the Pro in closer contact to the active site (activation energies for retinal release of 60.1 and 76.8 kcal/mol, respectively, compared to 115.8 kcal/mol for WT). FoldX analysis of the protein crystal structures indicates that the Pro-to-Ala mutations have both local and long-range effects on the structural stability of residues involved in the architecture of the protein and the active site and in the proton pumping function. Thus, this study provides a complete overview of the substitution effect of helix-embedded prolines in the thermodynamic and dynamic stability of a membrane protein, also related to its structure and function.
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30
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Fimland N, Rogne P, Fimland G, Nissen-Meyer J, Kristiansen PE. Three-dimensional structure of the two peptides that constitute the two-peptide bacteriocin plantaricin EF. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2008; 1784:1711-9. [PMID: 18555030 DOI: 10.1016/j.bbapap.2008.05.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2008] [Accepted: 05/05/2008] [Indexed: 10/22/2022]
Abstract
The three-dimensional structures of the two peptides plantaricin E (plnE; 33 residues) and plantaricin F (plnF; 34 residues) constituting the two-peptide bacteriocin plantaricin EF (plnEF) have been determined by nuclear magnetic resonance (NMR) spectroscopy in the presence of DPC micelles. PlnE has an N-terminal alpha-helix (residues 10-21), and a C-terminal alpha-helix-like structure (residues 25-31). PlnF has a long central alpha-helix (residues 7-32) with a kink of 38+/-7 degrees at Pro20. There is some flexibility in the helix in the kink region. Both helices in plnE are amphiphilic, while the helix in plnF is polar in its N-terminal half and amphiphilic in its C-terminal half. The alpha-helical content obtained by NMR spectroscopy is in agreement with CD studies. PlnE has two GxxxG motifs which are putative helix-helix interaction motifs, one at residues 5 to 9 and one at residues 20 to 24, while plnF has one such motif at residues 30 to 34. The peptides are flexible in these GxxxG regions. It is suggested that the two peptides lie parallel in a staggered fashion relative to each other and interact through helix-helix interactions involving the GxxxG motifs.
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Affiliation(s)
- Nina Fimland
- Department of Molecular Biosciences, University of Oslo, Pb. 1041 Blindern, 0316 Oslo, Norway
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31
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Drummer HE, Boo I, Poumbourios P. Mutagenesis of a conserved fusion peptide-like motif and membrane-proximal heptad-repeat region of hepatitis C virus glycoprotein E1. J Gen Virol 2007; 88:1144-1148. [PMID: 17374757 DOI: 10.1099/vir.0.82567-0] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The E1E2 glycoprotein heterodimer of Hepatitis C virus mediates viral entry. E2 attaches the virus to cellular receptors; however, the function of E1 is unknown. We tested the hypothesis that E1 is a truncated class II fusion protein. We mutated amino acids within a predicted fusion peptide (residues 276-286) and a truncated C-terminal stem-like motif, containing a membrane-proximal heptad-repeat sequence (residues 330-347). The fusion peptide mutation F285A abolished viral entry, while mutation of other hydrophobic residues had no effect. Alanine replacement of heptad-repeat residues blocked entry in three of five cases, whereas substitution with the helix breaker, Pro, led to loss of entry function in all cases. The mutations did not affect glycoprotein expression, heterodimerization with E2 or global folding, in contrast to the effects of mutations in the fusion motifs of prototypical class II fusion proteins. Our data suggest that E1 is unlikely to function in an analogous manner to other class II fusion glycoproteins.
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Affiliation(s)
- Heidi E Drummer
- Macfarlane Burnet Institute for Medical Research and Public Health Ltd, GPO Box 2284, Melbourne 3001, Australia
| | - Irene Boo
- Macfarlane Burnet Institute for Medical Research and Public Health Ltd, GPO Box 2284, Melbourne 3001, Australia
| | - Pantelis Poumbourios
- Macfarlane Burnet Institute for Medical Research and Public Health Ltd, GPO Box 2284, Melbourne 3001, Australia
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Snellman A, Tuomisto A, Koski A, Latvanlehto A, Pihlajaniemi T. The Role of Disulfide Bonds and α-Helical Coiled-coils in the Biosynthesis of Type XIII Collagen and Other Collagenous Transmembrane Proteins. J Biol Chem 2007; 282:14898-905. [PMID: 17344215 DOI: 10.1074/jbc.m609605200] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Type XIII collagen is a type II transmembrane protein with three collagenous (COL1-3) and four noncollagenous domains (NC1-4). The human alpha1(XIII) chain contains altogether eight cysteine residues. We introduced point mutations to six of the most N-terminal cysteine residues, and we show here that the two cysteines 117 and 119 at the end of the N-terminal noncollagenous domain (NC1) are responsible for linking the three alpha1(XIII) chains together by means of interchain disulfide bonds. In addition, the intracellular and transmembrane domains have an impact on trimer formation, whereas the cysteines in the transmembrane domain and the COL1, the NC2, and the C-terminal NC4 domains do not affect trimer formation. We also suggest that the first three noncollagenous domains (NC1-3) harbor repeating heptad sequences typical of alpha-helical coiled-coils, whereas the conserved NC4 lacks a coiled-coil probability. Prevention of the coiled-coil conformation in the NC3 domain is shown here to result in labile type XIII collagen molecules. Furthermore, a new subgroup of collagenous transmembrane proteins, the Rattus norvegicus, Drosophila melanogaster, and Caenorhabditis elegans colmedins, is enlarged to contain also Homo sapiens collomin, and Pan troglodytes, Mus musculus, Tetraodon nigroviridis, and Dano rerio proteins. We suggest that there is a structurally varied group of collagenous transmembrane proteins whose biosynthesis is characterized by a coiled-coil motif following the transmembrane domain, and that these trimerization domains appear to be associated with each of the collagenous domains. In the case of type XIII collagen, the trimeric molecule has disulfide bonds at the junction of the NC1 and COL1 domains, and the type XIII collagen-like molecules (collagen types XXIII and XXV) and the colmedins are similar in that they all have a pair of cysteines in the same location. Moreover, furin cleavage at the NC1 domain can be expected in most of the proteins.
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Affiliation(s)
- Anne Snellman
- Collagen Research Unit, Biocenter Oulu and Department of Medical Biochemistry and Molecular Biology, University of Oulu, PO Box 5000, FIN-90014 Oulu, Finland
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Mobley PW, Barry JA, Waring AJ, Sherman MA, Gordon LM. Membrane perturbing actions of HIV type 1 glycoprotein 41 domains are inhibited by helical C-peptides. AIDS Res Hum Retroviruses 2007; 23:224-42. [PMID: 17331029 DOI: 10.1089/aid.2006.0046] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
To study the membrane actions of various domains of HIV-1 glycoprotein 41,000 (gp41), synthetic peptides were prepared corresponding to the N-terminal fusion region (FP; gp41 residues 519-541), the nearby N-leucine zipper domain (N-peptides; DP-107; gp41 residues 560-597), the C-leucine zipper domain (C-peptides; DP-178; gp41 residues 645-680), and the viral envelope adjacent domain that partially overlaps DP-178 (Pre-TM; gp41 residues 671-690). With erythrocytes, FP, DP-107, and Pre-TM induced hemolysis and cell aggregation; the order for hemolytic activity was Pre-TM > FP > DP-107, but each was equally effective in aggregating cells at the highest peptide concentrations tested. DP-178 produced neither hemolysis nor aggregation, but efficiently reduced FP-, DP-107-, and Pre-TM-induced membrane actions. Fourier transform infrared spectroscopy indicated that the membrane perturbations of Pre-TM, as well as the ability of DP-178 to block membrane activities of other gp41 domains, are dependent on Pre-TM and DP-178 each maintaining helical conformations and tryptophans at residues 673, 677, and 679. These results suggest that the corresponding N-terminal fusion, N-leucine zipper, and viral membrane-adjacent regions of HIV-1 gp41 may similarly promote key membrane perturbations underlying the merging of the viral envelope with the cell surface. Further, the antiviral mechanism of exogenous DP-178 (clinically approved enfuvirtide) may be partially explained by its coordinate inhibition of the fusogenic actions of the FP, DP-107, and Pre-TM regions of gp41.
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Affiliation(s)
- Patrick W Mobley
- Chemistry Department, California State Polytechnic University, Pomona, CA 91768, USA
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34
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Moriarty DF, Fiorillo C, Miller C, Colón W. A truncated peptide model of the mutant P61A FIS forms a stable dimer. BIOCHIMICA ET BIOPHYSICA ACTA 2007; 1774:78-85. [PMID: 17118726 DOI: 10.1016/j.bbapap.2006.09.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2006] [Revised: 09/13/2006] [Accepted: 09/19/2006] [Indexed: 05/12/2023]
Abstract
Factor for inversion stimulation (FIS) is a 98-residue homodimeric DNA-binding protein involved in several different cellular processes including DNA inversion and the regulation of multiple genes. FIS contains a flexible and functionally important N-terminus followed by four helices (A-D), the last two of which consist of the DNA-binding region. Helix B, which comprises the main dimerization interface has a 20 degrees kink at its center that was originally thought to be caused by the presence of a proline at position 61. However, it was later shown that the kink remained largely intact and that FIS retained its native-like function when the proline was mutated to an alanine. We previously showed that the P61A mutation increased the stability of FIS, but decreased its equilibrium denaturation cooperativity apparently due to preferential stabilization of the B-helix. Here we studied a peptide of P61A FIS, corresponding to residues 26-71 (26-71(A3) FIS), which encompasses the dimer interface (helices A and B). Circular dichroism (CD) and size-exclusion chromatography/multi-angle light scattering showed that the peptide was alpha-helical and dimeric, respectively, as expected based on the 3D structure of FIS. Urea-induced equilibrium denaturation experiments monitored by far-UV CD revealed a concentration-dependent transition, and data analysis based on a N2<-->2U model yielded a DeltaG of approximately -10 kcal/mol. Our results suggest that 26-71(A3) FIS can form a stable dimeric structure despite lacking the N- and C-terminus of native FIS.
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Affiliation(s)
- Daniel F Moriarty
- Department of Chemistry and Chemical Biology, Rensselaer Polytechnic Institute, Troy, NY 12180, USA.
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35
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Sahai MA, Kehoe TAK, Koo JCP, Setiadi DH, Chass GA, Viskolcz B, Penke B, Pai EF, Csizmadia IG. First Principle Computational Study on the Full Conformational Space of l-Proline Diamides. J Phys Chem A 2005; 109:2660-79. [PMID: 16833573 DOI: 10.1021/jp040594i] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ab initio molecular orbital computations were carried out at three levels of theory: RHF/3-21G, RHF/6-31G(d), and B3LYP/6-31G(d), on four model systems of the amino acid proline, HCO-Pro-NH2 [I], HCO-Pro-NH-Me [II], MeCO-Pro-NH2 [III], and MeCO-Pro-NH-Me [IV], representing a systematic variation in the protecting N- and C-terminal groups. Three previously located backbone conformations, gammaL, epsilonL, and alphaL, were characterized together with two ring-puckered forms syn (gauche+ = g+) or "DOWN" and anti (gauche- = g-) or "UP", as well as trans-trans, trans-cis, cis-trans, and cis-cis peptide bond isomers. The topologies of the conformational potential energy cross-sections (PECS) of the potential energy hypersurfaces (PEHS) for compounds [I]-[IV] were explored and analyzed in terms of potential energy curves (PEC), and HCO-Pro-NH2 [I] was also analyzed in terms of potential energy surfaces (PESs). Thermodynamic functions were also calculated for HCO-Pro-NH2 [I] at the CBS-4M and G3MP2 levels of theory. The study confirms that the use of the simplest model, compound [I] with P(N) = P(C) = H, along with the RHF/3-21G level of theory, is an acceptable practice for the analysis of peptide models because only minor differences in geometry and stability are observed.
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Affiliation(s)
- Michelle A Sahai
- Department of Medical Biophysics, University of Toronto, Ontario Cancer Institute, Princess Margaret Hospital, 610 University Avenue, Toronto, Ontario, Canada M5G 2M9.
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Bruns K, Fossen T, Wray V, Henklein P, Tessmer U, Schubert U. Structural characterization of the HIV-1 Vpr N terminus: evidence of cis/trans-proline isomerism. J Biol Chem 2003; 278:43188-201. [PMID: 12881523 DOI: 10.1074/jbc.m305413200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The 96-residue human immunodeficiency virus (HIV) accessory protein Vpr serves manifold functions in the retroviral life cycle including augmentation of viral replication in non-dividing host cells, induction of G2 cell cycle arrest, and modulation of HIV-induced apoptosis. Using a combination of dynamic light scattering, circular dichroism, and NMR spectroscopy the N terminus of Vpr is shown to be a unique domain of the molecule that behaves differently from the C-terminal domain in terms of self-association and secondary structure folding. Interestingly, the four highly conserved proline residues in the N terminus are predicted to have a high propensity for cis/trans isomerism. Thus the high resolution structure and folding of a synthetic N-terminal peptide (Vpr1-40) and smaller fragments thereof have been investigated. 1H NMR data indicate Vpr1-40 possesses helical structure between residues 17-32, and for the first time, this helix, which is bound by proline residues, was observed even in aqueous solution devoid of any detergent supplements. In addition, NMR data revealed that all of the proline residues undergo a cis/ trans isomerism to such an extent that approximately 40% of all Vpr molecules possess at least one proline in a cis conformation. This phenomenon of cis/trans isomerism, which is unprecedented for HIV-1 Vpr, not only provides an explanation for the molecular heterogeneity observed in the full-length molecule but also indicates that in vivo the folding and function of Vpr should depend on a cis/trans-proline isomerase activity, particularly as two of the proline residues in positions 14 and 35 show considerable amounts of cis isomers. This prediction correlates well with our recent observation (Zander, K., Sherman, M. P., Tessmer, U., Bruns, K., Wray, V., Prechtel, A. T., Schubert, E., Henklein, P., Luban, J., Neidleman, J., Greene, W. C., and Schubert, U. (2003) J. Biol. Chem. 278, 43170-43181) of a functional interaction between the major cellular isomerase cyclophilin A and Vpr, both of which are incorporated into HIV-1 virions.
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Affiliation(s)
- Karsten Bruns
- Department of Structural Biology, Gesellschaft für Biotechnologische Forschung, D-38124 Braunschweig, Germany.
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Sjöberg M, Garoff H. Interactions between the transmembrane segments of the alphavirus E1 and E2 proteins play a role in virus budding and fusion. J Virol 2003; 77:3441-50. [PMID: 12610119 PMCID: PMC149539 DOI: 10.1128/jvi.77.6.3441-3450.2003] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The alphavirus envelope is built by heterodimers of the membrane proteins E1 and E2. The complex is formed as a p62E1 precursor in the endoplasmic reticulum. During transit to the plasma membrane (PM), it is cleaved into mature E1-E2 heterodimers, which are oligomerized into trimeric complexes, so-called spikes that bind both to each other and, at the PM, also to nucleocapsid (NC) structures under the membrane. These interactions drive the budding of new virus particles from the cell surface. The virus enters new cells by a low-pH-induced membrane fusion event where both inter- and intraheterodimer interactions are reorganized to establish a fusion-active membrane protein complex. There are no intact heterodimers left after fusion activation; instead, an E1 homotrimer remains in the cellular (or viral) membrane. We analyzed whether these transitions depend on interactions in the transmembrane (TM) region of the heterodimer. We observed a pattern of conserved glycines in the TM region of E1 and made two mutants where either the glycines only (SFV/E1(4L)) or the whole segment around the glycines (SFV/E1(11L)) was replaced by leucines. We found that both mutations decreased the stability of the heterodimer and increased the formation of the E1 homotrimer at a suboptimal fusion pH, while the fusion activity was decreased. This suggested that TM interactions play a role in virus assembly and entry and that anomalous or uncoordinated protein reorganizations take place in the mutants. In addition, the SFV/E1(11L) mutant was completely deficient in budding, which may reflect an inability to form multivalent NC interactions at the PM.
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Affiliation(s)
- Mathilda Sjöberg
- Department of Biosciences at Novum, Karolinska Institute, S-141 57 Huddinge, Sweden.
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38
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Abstract
Proline residues in the transmembrane (TM) alpha-helices of integral membrane proteins have long been suspected to play a key role for helix packing and signal transduction by inducing regions of helix distortion and/or dynamic flexibility (hinges). In this study we try to characterise the effect of proline on the geometric properties of TM alpha-helices. We have examined 199 transmembrane alpha-helices from polytopic membrane proteins of known structure. After examining the location of proline residues within the amino acid sequences of TM helices, we estimated the helix axes either side of a hinge and hence identified a hinge residue. This enabled us to calculate helix kink and swivel angles. The results of this analysis show that proline residues occur with a significant concentration in the centre of sequences of TM alpha-helices. In this location, they may induce formation of molecular hinges, located on average about four residues N-terminal to the proline residue. A superposition of proline-containing TM helices structures shows that the distortion induced is anisotropic and favours certain relative orientations (defined by helix kink and swivel angles) of the two helix segments.
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Affiliation(s)
- Frank S Cordes
- Laboratory of Molecular Biophysics, The Rex Richards Building, Department of Biochemistry, University of Oxford, South Parks Road, UK
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39
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Evans CA, Ariffin S, Pierce A, Whetton AD. Identification of primary structural features that define the differential actions of IL-3 and GM-CSF receptors. Blood 2002; 100:3164-74. [PMID: 12384414 DOI: 10.1182/blood-2001-12-0235] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Activation of human interleukin 3 (IL-3) and granulocyte-macrophage colony-stimulating factor (GM-CSF) receptors, ectopically expressed in FDCP-mix multipotent cells, stimulates self-renewal or myeloid differentiation, respectively. These receptors are composed of unique alpha subunits that interact with common beta(c) subunits. A chimeric receptor (hGM/beta(c)), comprising the extracellular domain of the hGM-CSF receptor alpha subunit (hGM Ralpha) fused to the intracellular domain of hbeta(c), was generated to determine whether hbeta(c) activation is alone sufficient to promote differentiation. hGM-CSF activation of hGM/beta(c), expressed in the presence and absence of the hbeta(c) subunit, promoted maintenance of primitive phenotype. This indicates that the cytosolic domain of the hGM Ralpha chain is required for differentiation mediated by activation of the hGM Ralpha, beta(c) receptor complex. We have previously demonstrated that the alpha cytosolic domain confers signal specificity for IL-3 and GM-CSF receptors. Bioinformatic analysis of the IL-3 Ralpha and GM Ralpha subunits identified a tripeptide sequence, adjacent to the conserved proline-rich domain, which was potentially a key difference between them. Cross-exchange of the equivalent tripeptides between the alpha subunits altered receptor function compared to the wild-type receptors. Both the mutant and the corresponding wild-type receptors promoted survival and proliferation in the short-term but had distinct effects on developmental outcome. The mutated hGM Ralpha promoted long-term proliferation and maintenance of primitive cell morphology, whereas cytokine activation of the corresponding hIL-3 Ralpha mutant promoted myeloid differentiation. We have thus identified a region of the alpha cytosolic domain that is of critical importance for defining receptor specificity.
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MESH Headings
- Amino Acid Motifs
- Amino Acid Sequence
- Animals
- Antigens, Differentiation/biosynthesis
- Antigens, Differentiation/genetics
- Cell Differentiation/drug effects
- Cell Line
- Cell Survival/drug effects
- Granulocyte-Macrophage Colony-Stimulating Factor/pharmacology
- Granulocytes/cytology
- Hematopoietic Stem Cells/cytology
- Hematopoietic Stem Cells/drug effects
- Humans
- Interleukin-3/pharmacology
- Macrophages/cytology
- Mice
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Phenotype
- Protein Structure, Tertiary
- Protein Subunits
- Receptors, Granulocyte-Macrophage Colony-Stimulating Factor/chemistry
- Receptors, Granulocyte-Macrophage Colony-Stimulating Factor/drug effects
- Receptors, Granulocyte-Macrophage Colony-Stimulating Factor/genetics
- Receptors, Interleukin-3/chemistry
- Receptors, Interleukin-3/drug effects
- Receptors, Interleukin-3/genetics
- Recombinant Fusion Proteins/chemistry
- Recombinant Fusion Proteins/drug effects
- Recombinant Fusion Proteins/genetics
- Sequence Alignment
- Sequence Homology, Amino Acid
- Structure-Activity Relationship
- Substrate Specificity
- Transfection
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Affiliation(s)
- Caroline A Evans
- Leukaemia Research Fund Cellular Development Unit, Department of Biomolecular Sciences, University of Manchester Institute of Science and Technology (UMIST), Sackville Street, Manchester M60 1QD, UK
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Smith BJ, Lawrence MC, Colman PM. Modelling the structure of the fusion protein from human respiratory syncytial virus. Protein Eng Des Sel 2002; 15:365-71. [PMID: 12034856 DOI: 10.1093/protein/15.5.365] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The fusion protein of respiratory syncytial virus (RSV-F) is responsible for fusion of virion with host cells and infection of neighbouring cells through the formation of syncytia. A three-dimensional model structure of RSV-F was derived by homology modelling from the structure of the equivalent protein in Newcastle disease virus (NDV). Despite very low sequence homology between the two structures, most features of the model appear to have high credibility, although a few small regions in RSV-F whose secondary structure is predicted to be different to that in NDV are likely to be poorly modelled. The organization of individual residues identified in escape mutants against monoclonal antibodies correlates well with known antigenic sites. The location of residues involved in point mutations in several drug-resistant variants is also examined.
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Affiliation(s)
- Brian J Smith
- Biomolecular Research Institute, 343 Royal Parade, Parkville, Victoria 3052, Australia
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41
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Hase ME, Kuznetsov NV, Cordes VC. Amino acid substitutions of coiled-coil protein Tpr abrogate anchorage to the nuclear pore complex but not parallel, in-register homodimerization. Mol Biol Cell 2001; 12:2433-52. [PMID: 11514627 PMCID: PMC58605 DOI: 10.1091/mbc.12.8.2433] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Tpr is a protein component of nuclear pore complex (NPC)-attached intranuclear filaments. Secondary structure predictions suggest a bipartite structure, with a large N-terminal domain dominated by heptad repeats (HRs) typical for coiled-coil--forming proteins. Proposed functions for Tpr have included roles as a homo- or heteropolymeric architectural element of the nuclear interior. To gain insight into Tpr's ultrastructural properties, we have studied recombinant Tpr segments by circular dichroism spectroscopy, chemical cross-linking, and rotary shadowing electron microscopy. We show that polypeptides of the N-terminal domain homodimerize in vitro and represent alpha-helical molecules of extended rod-like shape. With the use of a yeast two-hybrid approach, arrangement of the coiled-coil is found to be in parallel and in register. To clarify whether Tpr can self-assemble further into homopolymeric filaments, the full-length protein and deletion mutants were overexpressed in human cells and then analyzed by confocal immunofluorescence microscopy, cell fractionation, and immuno-electron microscopy. Surplus Tpr, which does not bind to the NPC, remains in a soluble state of approximately 7.5 S and occasionally forms aggregates of entangled molecules but neither self-assembles into extended linear filaments nor stably binds to other intranuclear structures. Binding to the NPC is shown to depend on the integrity of individual HRs; amino acid substitutions within these HRs abrogate NPC binding and render the protein soluble but do not abolish Tpr's general ability to homodimerize. Possible contributions of Tpr to the structural organization of the nuclear periphery in somatic cells are discussed.
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Affiliation(s)
- M E Hase
- Department of Cell and Molecular Biology, Medical Nobel Institute, Karolinska Institutet, S-17177 Stockholm, Sweden
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42
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Marx SO, Reiken S, Hisamatsu Y, Gaburjakova M, Gaburjakova J, Yang YM, Rosemblit N, Marks AR. Phosphorylation-dependent regulation of ryanodine receptors: a novel role for leucine/isoleucine zippers. J Cell Biol 2001; 153:699-708. [PMID: 11352932 PMCID: PMC2192391 DOI: 10.1083/jcb.153.4.699] [Citation(s) in RCA: 228] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Ryanodine receptors (RyRs), intracellular calcium release channels required for cardiac and skeletal muscle contraction, are macromolecular complexes that include kinases and phosphatases. Phosphorylation/dephosphorylation plays a key role in regulating the function of many ion channels, including RyRs. However, the mechanism by which kinases and phosphatases are targeted to ion channels is not well understood. We have identified a novel mechanism involved in the formation of ion channel macromolecular complexes: kinase and phosphatase targeting proteins binding to ion channels via leucine/isoleucine zipper (LZ) motifs. Activation of kinases and phosphatases bound to RyR2 via LZs regulates phosphorylation of the channel, and disruption of kinase binding via LZ motifs prevents phosphorylation of RyR2. Elucidation of this new role for LZs in ion channel macromolecular complexes now permits: (a) rapid mapping of kinase and phosphatase targeting protein binding sites on ion channels; (b) predicting which kinases and phosphatases are likely to regulate a given ion channel; (c) rapid identification of novel kinase and phosphatase targeting proteins; and (d) tools for dissecting the role of kinases and phosphatases as modulators of ion channel function.
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Affiliation(s)
- Steven O. Marx
- Center for Molecular Cardiology, Department of Medicine, Department of Pharmacology, College of Physicians and Surgeons of Columbia University, New York, New York 10032
| | - Steven Reiken
- Center for Molecular Cardiology, Department of Medicine, Department of Pharmacology, College of Physicians and Surgeons of Columbia University, New York, New York 10032
| | - Yuji Hisamatsu
- Center for Molecular Cardiology, Department of Medicine, Department of Pharmacology, College of Physicians and Surgeons of Columbia University, New York, New York 10032
| | - Marta Gaburjakova
- Center for Molecular Cardiology, Department of Medicine, Department of Pharmacology, College of Physicians and Surgeons of Columbia University, New York, New York 10032
| | - Jana Gaburjakova
- Center for Molecular Cardiology, Department of Medicine, Department of Pharmacology, College of Physicians and Surgeons of Columbia University, New York, New York 10032
| | - Yi-Ming Yang
- Center for Molecular Cardiology, Department of Medicine, Department of Pharmacology, College of Physicians and Surgeons of Columbia University, New York, New York 10032
| | - Nora Rosemblit
- Center for Molecular Cardiology, Department of Medicine, Department of Pharmacology, College of Physicians and Surgeons of Columbia University, New York, New York 10032
| | - Andrew R. Marks
- Center for Molecular Cardiology, Department of Medicine, Department of Pharmacology, College of Physicians and Surgeons of Columbia University, New York, New York 10032
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43
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Mobley PW, Pilpa R, Brown C, Waring AJ, Gordon LM. Membrane-perturbing domains of HIV type 1 glycoprotein 41. AIDS Res Hum Retroviruses 2001; 17:311-27. [PMID: 11242518 DOI: 10.1089/08892220150503681] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Structural and functional studies were performed to assess the membrane actions of peptides based on HIV-1 glycoprotein 41,000 (gp41). Previous site-directed mutagenesis of gp41 has shown that amino acid changes in either the N-terminal fusion or N-leucine zipper region depressed viral infection and syncytium formation, while modifications in the C-leucine zipper domain both increased and decreased HIV fusion. Here, synthetic peptides were prepared corresponding to the N-terminal fusion region (FP-I; gp41 residues 519-541), the nearby N-leucine zipper domain (DP-107; gp41 residues 560-597), and the C-leucine zipper domain (DP-178; gp41 residues 645-680). With erythrocytes, FP-I or DP-107 induced dose-dependent hemolysis and promoted cell aggregation; FP-I was more hemolytic than DP-107, but each was equally effective in aggregating cells. DP-178 produced neither hemolysis nor aggregation, but blocked either FP-I- or DP-107-induced hemolysis and aggregation. Combined with previous nuclear magnetic resonance and Fourier transform infrared spectroscopic results, circular dichroism (CD) spectroscopy showed that the alpha-helicity for these peptides in solution decreased in the order: DP-107 >> DP-178 > FP-I. CD analysis also indicated binding of DP-178 to either DP-107 or FP-I. Consequently, DP-178 may inhibit the membrane actions mediated by either FP-I or DP-107 through direct peptide interactions in solution. These peptide results suggest that the corresponding N-terminal fusion and N-leucine zipper regions participate in HIV infection, by promoting membrane perturbations underlying the merging of the viral envelope with the cell surface. Further, the C-leucine zipper domain in "prefusion" HIV may inhibit these membrane activities by interacting with the N-terminal fusion and N-leucine zipper domains in unactivated gp41. Last, exogenous DP-178 may bind to the N-terminal and N-leucine zipper domains of gp41 that become exposed on HIV stimulation, thereby preventing the fusogenic actions of these gp41 regions leading to infection.
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Affiliation(s)
- P W Mobley
- Chemistry Department, California State Polytechnic University, Pomona 91768, USA
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44
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Richter W, Unciuleac L, Hermsdorf T, Kronbach T, Dettmer D. Identification of substrate specificity determinants in human cAMP-specific phosphodiesterase 4A by single-point mutagenesis. Cell Signal 2001; 13:159-67. [PMID: 11282454 DOI: 10.1016/s0898-6568(01)00142-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
To identify amino acids that might be involved in discriminating guanosine-3',5'-cyclic phosphate (cGMP) towards adenosine-3',5'-cyclic phosphate (cAMP) binding in the cAMP-specific phosphodiesterases, alignments of different human cyclic nucleotide phosphodiesterases (PDEs) were performed. Eight amino acid residues that are highly conserved in the cAMP-hydrolysing phosphodiesterases (PDE1, PDE3, PDE4, PDE7, PDE8) and that did not show any homologies to the cGMP-specific phosphodiesterases (PDE5, PDE6, PDE9) were selected from these alignments. Using the technique of site-directed mutagenesis, derivatives of PDE4A carrying single mutations at these conserved residues (amino acid positions are given according to the human PDE4A isoform HSPDE4A4B; accession number L20965) were generated and expressed in COS1 cells. The expression products were characterised with regard to cAMP and cGMP hydrolysis and sensitivity towards type-specific inhibitors. The mutation of Phe484 toward Tyr, Ala590 toward Cys, Leu391 and Val501 towards Ala had no significant influence on substrate affinity or specificity. However, the exchange of Trp375 and Trp605 for aliphatic residues abolished catalytic activity and the exchange of Pro595 for Ile led to sevenfold decrease of substrate affinity and an 14-fold decrease of the affinity towards the PDE4-specific inhibitor 4-[3-(cyclopentoxyl)-4-methoxyphenyl]-2-pyrrolidone (rolipram). Both effects may provide evidence for a structural importance of Trp375, Trp605 and Pro595 for PDE function. By exchanging the aspartate residue for asparagine or alanine at position 440 of the human PDE4A4B isoform, the substrate specificity was altered from the highly specific cAMP hydrolysis to an equally efficient cAMP and cGMP binding and hydrolysis. In addition, the IC(50) values for common PDE4-specific inhibitors like rolipram, N-(3,5-dichlorpyrid-4-yl)-3-cyclopentyl-oxy-4-methoxy-benzamide (RPR-73401) and 8-methoxy-5-N-propyl-3-methyl-1-ethyl-imidazo[1,5-a]-pyrido[3,2-e]-pyrazinone (D-22888) were dramatically increased. These results demonstrate an important role of the aspartate at position 440 in determining substrate specificity and inhibitor susceptibility of PDE4A. The strong conservation of this residue suggests that Asp440 may play a similar role in other cAMP-PDEs.
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MESH Headings
- 3',5'-Cyclic-AMP Phosphodiesterases/antagonists & inhibitors
- 3',5'-Cyclic-AMP Phosphodiesterases/genetics
- 3',5'-Cyclic-AMP Phosphodiesterases/metabolism
- Amino Acid Sequence
- Amino Acid Substitution
- Aspartic Acid/genetics
- Binding, Competitive
- Blotting, Western
- Cells, Cultured
- Cyclic AMP/metabolism
- Cyclic GMP/metabolism
- Cyclic Nucleotide Phosphodiesterases, Type 1
- Cyclic Nucleotide Phosphodiesterases, Type 4
- DNA, Complementary/genetics
- Electrophoresis, Polyacrylamide Gel
- Gene Expression Regulation, Enzymologic/drug effects
- Humans
- Isoenzymes/chemistry
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Phosphodiesterase Inhibitors/pharmacology
- Polymerase Chain Reaction
- RNA, Messenger/metabolism
- Rolipram/pharmacology
- Sequence Alignment
- Substrate Specificity/genetics
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Affiliation(s)
- W Richter
- Institute of Biochemistry, Medical Faculty, University of Leipzig, Liebigstrasse 16, D-04103, Leipzig, Germany
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45
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Vacratsis PO, Gallo KA. Zipper-mediated oligomerization of the mixed lineage kinase SPRK/MLK-3 is not required for its activation by the GTPase cdc 42 but Is necessary for its activation of the JNK pathway. Monomeric SPRK L410P does not catalyze the activating phosphorylation of Thr258 of murine MITOGEN-ACTIVATED protein kinase kinase 4. J Biol Chem 2000; 275:27893-900. [PMID: 10862766 DOI: 10.1074/jbc.m002858200] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Src homology 3 domain-containing proline-rich kinase (SPRK)/mixed lineage kinase-3 is a serine/threonine kinase that has been identified as an upstream activator of the c-Jun NH(2)-terminal kinase (JNK) pathway. SPRK is capable of activating MKK4 by phosphorylation of serine and threonine residues, and mutant forms of MKK4 that lack the phosphorylation sites Ser(254) and Thr(258) block SPRK-induced JNK activation. A region of 63 amino acids following the kinase domain of SPRK is predicted to form a leucine zipper. The leucine zipper domain of SPRK has been shown to be necessary and sufficient for SPRK oligomerization, but its role in regulating activation of SPRK and downstream signaling remains unclear. In this study, we substituted a proposed stabilizing leucine residue in the zipper domain with a helix-disrupting proline to abrogate zipper-mediated SPRK oligomerization. We demonstrate that constitutively activated Cdc42 fully activates this monomeric SPRK mutant in terms of both autophosphorylation and histone phosphorylation activity and induces the same in vivo phosphorylation pattern as wild type SPRK. However, this catalytically active SPRK zipper mutant is unable to activate JNK. Our data show that the monomeric SPRK mutant fails to phosphorylate one of the two activating phosphorylation sites, Thr(258), of MKK4. These studies suggest that zipper-mediated SPRK oligomerization is not required for SPRK activation by Cdc42 but instead is critical for proper interaction and phosphorylation of a downstream target, MKK4.
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Affiliation(s)
- P O Vacratsis
- Departments of Biochemistry and Physiology, Michigan State University, East Lansing, Michigan 48824, USA
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