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  • 1
    Publication Date: 2014-09-16
    Description: The Ras-like GTPases RalA and RalB are important drivers of tumour growth and metastasis. Chemicals that block Ral function would be valuable as research tools and for cancer therapeutics. Here we used protein structure analysis and virtual screening to identify drug-like molecules that bind to a site on the GDP-bound form of Ral. The compounds RBC6, RBC8 and RBC10 inhibited the binding of Ral to its effector RALBP1, as well as inhibiting Ral-mediated cell spreading of murine embryonic fibroblasts and anchorage-independent growth of human cancer cell lines. The binding of the RBC8 derivative BQU57 to RalB was confirmed by isothermal titration calorimetry, surface plasmon resonance and (1)H-(15)N transverse relaxation-optimized spectroscopy (TROSY) NMR spectroscopy. RBC8 and BQU57 show selectivity for Ral relative to the GTPases Ras and RhoA and inhibit tumour xenograft growth to a similar extent to the depletion of Ral using RNA interference. Our results show the utility of structure-based discovery for the development of therapeutics for Ral-dependent cancers.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4351747/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4351747/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Yan, Chao -- Liu, Degang -- Li, Liwei -- Wempe, Michael F -- Guin, Sunny -- Khanna, May -- Meier, Jeremy -- Hoffman, Brenton -- Owens, Charles -- Wysoczynski, Christina L -- Nitz, Matthew D -- Knabe, William E -- Ahmed, Mansoor -- Brautigan, David L -- Paschal, Bryce M -- Schwartz, Martin A -- Jones, David N M -- Ross, David -- Meroueh, Samy O -- Theodorescu, Dan -- CA075115/CA/NCI NIH HHS/ -- CA091846/CA/NCI NIH HHS/ -- CA104106/CA/NCI NIH HHS/ -- GM47214/GM/NIGMS NIH HHS/ -- P01 CA104106/CA/NCI NIH HHS/ -- P30 CA044579/CA/NCI NIH HHS/ -- P30 CA046934/CA/NCI NIH HHS/ -- P50 CA091846/CA/NCI NIH HHS/ -- R01 CA075115/CA/NCI NIH HHS/ -- R01 CA143971/CA/NCI NIH HHS/ -- T32 GM007635/GM/NIGMS NIH HHS/ -- UL1 TR001082/TR/NCATS NIH HHS/ -- UL1TR001082/TR/NCATS NIH HHS/ -- England -- Nature. 2014 Nov 20;515(7527):443-7. doi: 10.1038/nature13713. Epub 2014 Sep 14.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Surgery, University of Colorado, Aurora, Colorado 80045, USA. ; Department of Biochemistry, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA. ; Department of Pharmaceutical Sciences, University of Colorado, Aurora, Colorado 80045, USA. ; Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia 22908, USA. ; Department of Pharmacology, University of Colorado, Aurora, Colorado 80045, USA. ; Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, Virginia 22908, USA. ; 1] Department of Cardiology, Yale University, New Haven, Connecticut 06511, USA [2] Department of Cell Biology, Yale University, New Haven, Connecticut 06511, USA. ; Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, Virginia 22908, USA. ; 1] Department of Biochemistry, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA [2] Department of Chemistry and Chemical Biology, Indiana University - Purdue University, Indianapolis, Indiana 46202, USA. ; 1] Department of Surgery, University of Colorado, Aurora, Colorado 80045, USA [2] Department of Pharmacology, University of Colorado, Aurora, Colorado 80045, USA [3] University of Colorado Comprehensive Cancer Center, Aurora, Colorado 80045, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25219851" target="_blank"〉PubMed〈/a〉
    Keywords: ATP-Binding Cassette Transporters/metabolism ; Animals ; Cell Line, Tumor ; Cell Proliferation/drug effects ; Computer Simulation ; *Drug Screening Assays, Antitumor ; Female ; GTPase-Activating Proteins/metabolism ; Humans ; Mice ; Models, Molecular ; *Molecular Targeted Therapy ; Neoplasms/drug therapy/enzymology/metabolism/pathology ; Protein Binding/drug effects ; Signal Transduction/drug effects ; Small Molecule Libraries/*chemistry/*pharmacology ; Substrate Specificity ; Xenograft Model Antitumor Assays ; ral GTP-Binding Proteins/*antagonists & inhibitors/chemistry/metabolism ; ras Proteins/metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2019-07-19
    Description: Onboard the Mars Science Laboratory (MSL) Curiosity rover, the ChemCam instrument consists of :(1) a Laser-Induced Breakdown Spectrometer (LIBS) for elemental analysis of the targets [1;2] and (2) a Remote Micro Imager (RMI), for the imaging context of laser analysis [3]. Within the Gale crater, Curiosity traveled from Bradbury Landing through the Rocknest region and into Yellowknife Bay (YB). In the latter, abundant light-toned fracture-fill material were seen [4;5]. ChemCam analysis demonstrate that those fracture fills consist of calcium sulfates [6].
    Keywords: Geophysics
    Type: JSC-CN-31277 , International Conference on Mars; Jul 14, 2014 - Jul 18, 2014; Pasadena, CA; United States
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  • 3
    Publication Date: 2014-03-05
    Description: Antibodies capable of neutralizing HIV-1 often target variable regions 1 and 2 (V1V2) of the HIV-1 envelope, but the mechanism of their elicitation has been unclear. Here we define the developmental pathway by which such antibodies are generated and acquire the requisite molecular characteristics for neutralization. Twelve somatically related neutralizing antibodies (CAP256-VRC26.01-12) were isolated from donor CAP256 (from the Centre for the AIDS Programme of Research in South Africa (CAPRISA)); each antibody contained the protruding tyrosine-sulphated, anionic antigen-binding loop (complementarity-determining region (CDR) H3) characteristic of this category of antibodies. Their unmutated ancestor emerged between weeks 30-38 post-infection with a 35-residue CDR H3, and neutralized the virus that superinfected this individual 15 weeks after initial infection. Improved neutralization breadth and potency occurred by week 59 with modest affinity maturation, and was preceded by extensive diversification of the virus population. HIV-1 V1V2-directed neutralizing antibodies can thus develop relatively rapidly through initial selection of B cells with a long CDR H3, and limited subsequent somatic hypermutation. These data provide important insights relevant to HIV-1 vaccine development.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4395007/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4395007/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Doria-Rose, Nicole A -- Schramm, Chaim A -- Gorman, Jason -- Moore, Penny L -- Bhiman, Jinal N -- DeKosky, Brandon J -- Ernandes, Michael J -- Georgiev, Ivelin S -- Kim, Helen J -- Pancera, Marie -- Staupe, Ryan P -- Altae-Tran, Han R -- Bailer, Robert T -- Crooks, Ema T -- Cupo, Albert -- Druz, Aliaksandr -- Garrett, Nigel J -- Hoi, Kam H -- Kong, Rui -- Louder, Mark K -- Longo, Nancy S -- McKee, Krisha -- Nonyane, Molati -- O'Dell, Sijy -- Roark, Ryan S -- Rudicell, Rebecca S -- Schmidt, Stephen D -- Sheward, Daniel J -- Soto, Cinque -- Wibmer, Constantinos Kurt -- Yang, Yongping -- Zhang, Zhenhai -- NISC Comparative Sequencing Program -- Mullikin, James C -- Binley, James M -- Sanders, Rogier W -- Wilson, Ian A -- Moore, John P -- Ward, Andrew B -- Georgiou, George -- Williamson, Carolyn -- Abdool Karim, Salim S -- Morris, Lynn -- Kwong, Peter D -- Shapiro, Lawrence -- Mascola, John R -- P01 AI082362/AI/NIAID NIH HHS/ -- R01 AI100790/AI/NIAID NIH HHS/ -- UM1 AI100663/AI/NIAID NIH HHS/ -- Intramural NIH HHS/ -- Wellcome Trust/United Kingdom -- England -- Nature. 2014 May 1;509(7498):55-62. doi: 10.1038/nature13036. Epub 2014 Mar 2.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉1] Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA [2]. ; 1] Department of Biochemistry, Columbia University, New York, New York 10032, USA [2]. ; 1] Center for HIV and STIs, National Institute for Communicable Diseases of the National Health Laboratory Service (NHLS), Johannesburg, 2131, South Africa [2] Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, 2050, South Africa [3] Centre for the AIDS Programme of Research in South Africa (CAPRISA), University of KwaZulu-Natal, Congella, 4013, South Africa [4]. ; 1] Center for HIV and STIs, National Institute for Communicable Diseases of the National Health Laboratory Service (NHLS), Johannesburg, 2131, South Africa [2] Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, 2050, South Africa. ; Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, USA. ; Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA. ; 1] Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California 92037, USA [2] Center for HIV/AIDS Vaccine Immunology and Immunogen Discovery, The Scripps Research Institute, La Jolla, California 92037, USA [3] IAVI Neutralizing Antibody Center, The Scripps Research Institute, La Jolla, California 92037, USA. ; Torrey Pines Institute, San Diego, California 92037, USA. ; Weill Medical College of Cornell University, New York, New York 10065, USA. ; Centre for the AIDS Programme of Research in South Africa (CAPRISA), University of KwaZulu-Natal, Congella, 4013, South Africa. ; Department of Biomedical Engineering, University of Texas at Austin, Austin, Texas, USA. ; Center for HIV and STIs, National Institute for Communicable Diseases of the National Health Laboratory Service (NHLS), Johannesburg, 2131, South Africa. ; Institute of Infectious Diseases and Molecular Medicine, Division of Medical Virology, University of Cape Town and NHLS, Cape Town 7701, South Africa. ; Department of Biochemistry, Columbia University, New York, New York 10032, USA. ; 1] NISC Comparative Sequencing program, National Institutes of Health, Bethesda, Maryland 20892, USA [2] NIH Intramural Sequencing Center, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland 20892, USA. ; Department of Medical Microbiology, Academic Medical Center, Amsterdam 1105 AZ, Netherlands. ; 1] Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California 92037, USA [2] Center for HIV/AIDS Vaccine Immunology and Immunogen Discovery, The Scripps Research Institute, La Jolla, California 92037, USA [3] IAVI Neutralizing Antibody Center, The Scripps Research Institute, La Jolla, California 92037, USA [4] Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, California 92037, USA. ; 1] Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, USA [2] Department of Biomedical Engineering, University of Texas at Austin, Austin, Texas, USA [3] Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas 78712, USA. ; 1] Centre for the AIDS Programme of Research in South Africa (CAPRISA), University of KwaZulu-Natal, Congella, 4013, South Africa [2] Institute of Infectious Diseases and Molecular Medicine, Division of Medical Virology, University of Cape Town and NHLS, Cape Town 7701, South Africa. ; 1] Centre for the AIDS Programme of Research in South Africa (CAPRISA), University of KwaZulu-Natal, Congella, 4013, South Africa [2] Department of Epidemiology, Columbia University, New York, New York 10032, USA. ; 1] Center for HIV and STIs, National Institute for Communicable Diseases of the National Health Laboratory Service (NHLS), Johannesburg, 2131, South Africa [2] Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, 2050, South Africa [3] Centre for the AIDS Programme of Research in South Africa (CAPRISA), University of KwaZulu-Natal, Congella, 4013, South Africa. ; 1] Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA [2] Department of Biochemistry, Columbia University, New York, New York 10032, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24590074" target="_blank"〉PubMed〈/a〉
    Keywords: AIDS Vaccines/chemistry/immunology ; Amino Acid Sequence ; Antibodies, Neutralizing/chemistry/genetics/*immunology/isolation & purification ; Antibody Affinity/genetics/immunology ; Antigens, CD4/immunology/metabolism ; B-Lymphocytes/cytology/immunology/metabolism ; Binding Sites/immunology ; Cell Lineage ; Complementarity Determining Regions/chemistry/genetics/immunology ; Epitope Mapping ; Epitopes, B-Lymphocyte/chemistry/immunology ; Evolution, Molecular ; HIV Antibodies/chemistry/genetics/*immunology/isolation & purification ; HIV Envelope Protein gp160/*chemistry/*immunology ; HIV Infections/immunology ; HIV-1/chemistry/immunology ; Humans ; Models, Molecular ; Molecular Sequence Data ; Neutralization Tests ; Protein Structure, Tertiary ; Somatic Hypermutation, Immunoglobulin/genetics
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 4
    Publication Date: 2014-11-20
    Description: Oxidative stress promotes genomic instability and human diseases. A common oxidized nucleoside is 8-oxo-7,8-dihydro-2'-deoxyguanosine, which is found both in DNA (8-oxo-G) and as a free nucleotide (8-oxo-dGTP). Nucleotide pools are especially vulnerable to oxidative damage. Therefore cells encode an enzyme (MutT/MTH1) that removes free oxidized nucleotides. This cleansing function is required for cancer cell survival and to modulate Escherichia coli antibiotic sensitivity in a DNA polymerase (pol)-dependent manner. How polymerases discriminate between damaged and non-damaged nucleotides is not well understood. This analysis is essential given the role of oxidized nucleotides in mutagenesis, cancer therapeutics, and bacterial antibiotics. Even with cellular sanitizing activities, nucleotide pools contain enough 8-oxo-dGTP to promote mutagenesis. This arises from the dual coding potential where 8-oxo-dGTP(anti) base pairs with cytosine and 8-oxo-dGTP(syn) uses its Hoogsteen edge to base pair with adenine. Here we use time-lapse crystallography to follow 8-oxo-dGTP insertion opposite adenine or cytosine with human pol beta, to reveal that insertion is accommodated in either the syn- or anti-conformation, respectively. For 8-oxo-dGTP(anti) insertion, a novel divalent metal relieves repulsive interactions between the adducted guanine base and the triphosphate of the oxidized nucleotide. With either templating base, hydrogen-bonding interactions between the bases are lost as the enzyme reopens after catalysis, leading to a cytotoxic nicked DNA repair intermediate. Combining structural snapshots with kinetic and computational analysis reveals how 8-oxo-dGTP uses charge modulation during insertion that can lead to a blocked DNA repair intermediate.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4312183/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4312183/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Freudenthal, Bret D -- Beard, William A -- Perera, Lalith -- Shock, David D -- Kim, Taejin -- Schlick, Tamar -- Wilson, Samuel H -- 1U19CA105010/CA/NCI NIH HHS/ -- U19 CA177547/CA/NCI NIH HHS/ -- Z01-ES050158/ES/NIEHS NIH HHS/ -- Z01-ES050161/ES/NIEHS NIH HHS/ -- ZIA ES050158-18/Intramural NIH HHS/ -- ZIA ES050159-18/Intramural NIH HHS/ -- ZIC-ES043010/ES/NIEHS NIH HHS/ -- England -- Nature. 2015 Jan 29;517(7536):635-9. doi: 10.1038/nature13886. Epub 2014 Nov 17.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Structural Biology, National Institute of Environmental Health Sciences, National Institutes of Health, PO Box 12233, Research Triangle Park, North Carolina 27709-2233, USA. ; 1] Department of Chemistry, New York University, and NYU-ECNU Center for Computational Chemistry at NYU Shanghai, 10th Floor Silver Center, 100 Washington Square East, New York, New York 10003, USA [2] Courant Institute of Mathematical Sciences, New York University, 251 Mercer Street, New York, New York 10012, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25409153" target="_blank"〉PubMed〈/a〉
    Keywords: Adenine/chemistry/metabolism ; Base Pairing ; Catalytic Domain ; Crystallography, X-Ray ; Cytosine/chemistry/metabolism ; Cytotoxins/chemistry/*metabolism/toxicity ; DNA/biosynthesis/chemistry ; *DNA Damage ; DNA Polymerase beta/*chemistry/*metabolism ; DNA Repair ; DNA Replication ; Deoxyguanine Nucleotides/chemistry/*metabolism/*toxicity ; Guanine/analogs & derivatives/chemistry/metabolism ; Humans ; Hydrogen Bonding ; Kinetics ; Models, Molecular ; Molecular Conformation ; *Mutagenesis ; Neoplasms/enzymology/genetics ; Oxidation-Reduction ; Oxidative Stress ; Static Electricity ; Substrate Specificity ; Time Factors
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 5
    Publication Date: 2014-04-20
    Description: Cytoplasmic plant immune receptors recognize specific pathogen effector proteins and initiate effector-triggered immunity. In Arabidopsis, the immune receptors RPS4 and RRS1 are both required to activate defense to three different pathogens. We show that RPS4 and RRS1 physically associate. Crystal structures of the N-terminal Toll-interleukin-1 receptor/resistance (TIR) domains of RPS4 and RRS1, individually and as a heterodimeric complex (respectively at 2.05, 1.75, and 2.65 angstrom resolution), reveal a conserved TIR/TIR interaction interface. We show that TIR domain heterodimerization is required to form a functional RRS1/RPS4 effector recognition complex. The RPS4 TIR domain activates effector-independent defense, which is inhibited by the RRS1 TIR domain through the heterodimerization interface. Thus, RPS4 and RRS1 function as a receptor complex in which the two components play distinct roles in recognition and signaling.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Williams, Simon J -- Sohn, Kee Hoon -- Wan, Li -- Bernoux, Maud -- Sarris, Panagiotis F -- Segonzac, Cecile -- Ve, Thomas -- Ma, Yan -- Saucet, Simon B -- Ericsson, Daniel J -- Casey, Lachlan W -- Lonhienne, Thierry -- Winzor, Donald J -- Zhang, Xiaoxiao -- Coerdt, Anne -- Parker, Jane E -- Dodds, Peter N -- Kobe, Bostjan -- Jones, Jonathan D G -- New York, N.Y. -- Science. 2014 Apr 18;344(6181):299-303. doi: 10.1126/science.1247357.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉School of Chemistry and Molecular Biosciences and Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD 4072, Australia.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24744375" target="_blank"〉PubMed〈/a〉
    Keywords: Agrobacterium/physiology ; Amino Acid Motifs ; Arabidopsis/chemistry/*immunology/microbiology ; Arabidopsis Proteins/*chemistry/genetics/metabolism ; Bacterial Proteins/immunology/metabolism ; Cell Death ; Crystallography, X-Ray ; Immunity, Innate ; Models, Molecular ; Mutation ; Plant Diseases/immunology/microbiology ; Plant Leaves/microbiology ; Plant Proteins/*chemistry/genetics/metabolism ; Plants, Genetically Modified ; Protein Interaction Domains and Motifs ; Protein Multimerization ; Protein Structure, Secondary ; Protein Structure, Tertiary ; Receptors, Immunologic/*chemistry/genetics/metabolism ; Signal Transduction ; Tobacco/genetics/immunology/metabolism/microbiology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 6
    Publication Date: 2019-07-13
    Description: Two recent papers have quantified long-term ozone (O3) changes observed at northernmidlatitude sites that are believed to represent baseline (here understood as representative of continental to hemispheric scales) conditions. Three chemistry-climate models (NCAR CAM-chem, GFDL-CM3, and GISS-E2-R) have calculated retrospective tropospheric O3 concentrations as part of the Atmospheric Chemistry and Climate Model Intercomparison Project and Coupled Model Intercomparison Project Phase 5 model intercomparisons. We present an approach for quantitative comparisons of model results with measurements for seasonally averaged O3 concentrations. There is considerable qualitative agreement between the measurements and the models, but there are also substantial and consistent quantitative disagreements. Most notably, models (1) overestimate absolute O3 mixing ratios, on average by approximately 5 to 17 ppbv in the year 2000, (2) capture only approximately 50% of O3 changes observed over the past five to six decades, and little of observed seasonal differences, and (3) capture approximately 25 to 45% of the rate of change of the long-term changes. These disagreements are significant enough to indicate that only limited confidence can be placed on estimates of present-day radiative forcing of tropospheric O3 derived from modeled historic concentration changes and on predicted future O3 concentrations. Evidently our understanding of tropospheric O3, or the incorporation of chemistry and transport processes into current chemical climate models, is incomplete. Modeled O3 trends approximately parallel estimated trends in anthropogenic emissions of NO(sub x), an important O3 precursor, while measured O3 changes increase more rapidly than these emission estimates.
    Keywords: Geophysics
    Type: GSFC-E-DAA-TN18647 , Journal of Geophysical Research: Atmospheres; 119; 9; 5719-5736
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  • 7
    Publication Date: 2019-07-13
    Description: We present a detailed outline and discussion of the analysis techniques used to compare the relevance of different energy dissipation mechanisms at collisionless shock waves. We show that the low-frequency, quasi-static fields contribute less to ohmic energy dissipation, (j E ) (minus current density times measured electric field), than their high-frequency counterparts. In fact, we found that high-frequency, large-amplitude (greater than 100 millivolts per meter and/or greater than 1 nanotesla) waves are ubiquitous in the transition region of collisionless shocks. We quantitatively show that their fields, through wave-particle interactions, cause enough energy dissipation to regulate the global structure of collisionless shocks. The purpose of this paper, part one of two, is to outline and describe in detail the background, analysis techniques, and theoretical motivation for our new results presented in the companion paper. The companion paper presents the results of our quantitative energy dissipation rate estimates and discusses the implications. Together, the two manuscripts present the first study quantifying the contribution that high-frequency waves provide, through wave-particle interactions, to the total energy dissipation budget of collisionless shock waves.
    Keywords: Geophysics
    Type: GSFC-E-DAA-TN31886 , Journal of Geophysical Research: Space Physics (ISSN 2169-9380) (e-ISSN 2169-9402); 119; 8; 6455–6474
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  • 8
    Publication Date: 2019-07-13
    Description: We present the first quantified measure of the energy dissipation rates, due to wave-particle interactions, in the transition region of the Earth's collision-less bow shock using data from the Time History of Events and Macro-Scale Interactions during Sub-Storms spacecraft. Our results show that wave-particle interactions can regulate the global structure and dominate the energy dissipation of collision-less shocks. In every bow shock crossing examined, we observed both low-frequency (less than 10 hertz) and high-frequency (approximately or greater than10 hertz) electromagnetic waves throughout the entire transition region and into the magnetosheath. The low-frequency waves were consistent with magnetosonic-whistler waves. The high-frequency waves were combinations of ion-acoustic waves, electron cyclotron drift instability driven waves, electrostatic solitary waves, and whistler mode waves. The high-frequency waves had the following: (1) peak amplitudes exceeding delta B approximately equal to 10 nanoteslas and delta E approximately equal to 300 millivolts per meter, though more typical values were delta B approximately equal to 0.1-1.0 nanoteslas and delta E approximately equal to 10-50 millivolts per meter (2) Poynting fluxes in excess of 2000 microWm(sup 2) (micro-waves per square meter) (typical values were approximately 1-10 microWm(sup 2) (micro-waves per square meter); (3) resistivities greater than 9000 omega meters; and (4) associated energy dissipation rates greater than 10 microWm(sup 3) (micro-waves per cubic meter). The dissipation rates due to wave-particle interactions exceeded rates necessary to explain the increase in entropy across the shock ramps for approximately 90 percent of the wave burst durations. For approximately 22 percent of these times, the wave-particle interactions needed to only be less than or equal to 0.1 percent efficient to balance the nonlinear wave steepening that produced the shock waves. These results show that wave-particle interactions have the capacity to regulate the global structure and dominate the energy dissipation of collision-less shocks.
    Keywords: Geophysics
    Type: GSFC-E-DAA-TN31887 , Journal of Geophysical Research: Space Physics (e-ISSN 2169-9402); 119; 8; 6475-6495
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  • 9
    Publication Date: 2014-04-26
    Description: The hierarchical packaging of eukaryotic chromatin plays a central role in transcriptional regulation and other DNA-related biological processes. Here, we report the 11-angstrom-resolution cryogenic electron microscopy (cryo-EM) structures of 30-nanometer chromatin fibers reconstituted in the presence of linker histone H1 and with different nucleosome repeat lengths. The structures show a histone H1-dependent left-handed twist of the repeating tetranucleosomal structural units, within which the four nucleosomes zigzag back and forth with a straight linker DNA. The asymmetric binding and the location of histone H1 in chromatin play a role in the formation of the 30-nanometer fiber. Our results provide mechanistic insights into how nucleosomes compact into higher-order chromatin fibers.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Song, Feng -- Chen, Ping -- Sun, Dapeng -- Wang, Mingzhu -- Dong, Liping -- Liang, Dan -- Xu, Rui-Ming -- Zhu, Ping -- Li, Guohong -- New York, N.Y. -- Science. 2014 Apr 25;344(6182):376-80. doi: 10.1126/science.1251413.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24763583" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Chromatin/chemistry/metabolism/*ultrastructure ; Cryoelectron Microscopy ; DNA/chemistry/*ultrastructure ; Histones/*chemistry/metabolism ; Imaging, Three-Dimensional ; Models, Molecular ; Molecular Sequence Data ; Nucleic Acid Conformation ; Nucleosomes/*ultrastructure ; Protein Conformation ; Recombinant Proteins/chemistry/metabolism ; Xenopus Proteins/chemistry ; Xenopus laevis
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 10
    Publication Date: 2014-05-30
    Description: The self-assembly of proteins into highly ordered nanoscale architectures is a hallmark of biological systems. The sophisticated functions of these molecular machines have inspired the development of methods to engineer self-assembling protein nanostructures; however, the design of multi-component protein nanomaterials with high accuracy remains an outstanding challenge. Here we report a computational method for designing protein nanomaterials in which multiple copies of two distinct subunits co-assemble into a specific architecture. We use the method to design five 24-subunit cage-like protein nanomaterials in two distinct symmetric architectures and experimentally demonstrate that their structures are in close agreement with the computational design models. The accuracy of the method and the number and variety of two-component materials that it makes accessible suggest a route to the construction of functional protein nanomaterials tailored to specific applications.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4137318/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4137318/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉King, Neil P -- Bale, Jacob B -- Sheffler, William -- McNamara, Dan E -- Gonen, Shane -- Gonen, Tamir -- Yeates, Todd O -- Baker, David -- T32 GM067555/GM/NIGMS NIH HHS/ -- T32GM067555/GM/NIGMS NIH HHS/ -- Howard Hughes Medical Institute/ -- England -- Nature. 2014 Jun 5;510(7503):103-8. doi: 10.1038/nature13404. Epub 2014 May 25.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉1] Department of Biochemistry, University of Washington, Seattle, Washington 98195, USA [2] Institute for Protein Design, University of Washington, Seattle, Washington 98195, USA [3]. ; 1] Department of Biochemistry, University of Washington, Seattle, Washington 98195, USA [2] Graduate Program in Molecular and Cellular Biology, University of Washington, Seattle, Washington 98195, USA [3]. ; 1] Department of Biochemistry, University of Washington, Seattle, Washington 98195, USA [2]. ; UCLA Department of Chemistry and Biochemistry, Los Angeles, California 90095, USA. ; 1] Department of Biochemistry, University of Washington, Seattle, Washington 98195, USA [2] Janelia Farm Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, Virginia 20147, USA. ; Janelia Farm Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, Virginia 20147, USA. ; 1] UCLA Department of Chemistry and Biochemistry, Los Angeles, California 90095, USA [2] UCLA-DOE Institute for Genomics and Proteomics, Los Angeles, California 90095, USA [3] UCLA Molecular Biology Institute, Los Angeles, California 90095, USA. ; 1] Department of Biochemistry, University of Washington, Seattle, Washington 98195, USA [2] Institute for Protein Design, University of Washington, Seattle, Washington 98195, USA [3] Howard Hughes Medical Institute, University of Washington, Seattle, Washington 98195, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24870237" target="_blank"〉PubMed〈/a〉
    Keywords: Computer Simulation ; Crystallography, X-Ray ; Drug Design ; Models, Molecular ; Nanostructures/*chemistry/ultrastructure ; Protein Subunits/chemistry ; Proteins/*chemistry/ultrastructure
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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