네이처 컨텐츠

Editorial

Time for the social sciences p.5

Governments that want the natural sciences to deliver more for society need to show greater commitment towards the social sciences and humanities.

doi: 10.1038/517005a

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News

News Features

Science in 2015 p.12

From Gradzilla to coffee consumption: the research enterprise quantified for the year to come.

Mark Zastrow

doi: 10.1038/517012a

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News & Views

Entry signals control development p.24

Certain structural elements allow messenger RNAs not usually processed by the protein-synthesis apparatus to be translated. It now seems that they also control the expression of genes involved in embryonic development. See Article p.33

Jonathan D. Dinman

doi: 10.1038/nature14069

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Like cartilage, but simpler p.25

The properties of articular cartilage, which lines bones in joints, depend partly on repulsion between components of the material. A new synthetic gel that mimics this feature has rare, direction-dependent properties. See Letter p.68

Anne Ladegaard Skov

doi: 10.1038/517025a

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Photosynthetic complex in close-up p.26

Photosystem II, a photosynthetic protein complex, is prone to X-ray damage during crystallography. A high-resolution structure of the undamaged complex now offers a detailed view of its catalytic centre. See Letter p.99

Ilme Schlichting

doi: 10.1038/nature14072

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Diverted on the way to memory p.28

The finding that protein A of Staphylococcus aureus diverts the immune response so that it ineffectively responds to other structures from the bacterium explains the failure of ongoing attempts to develop working S. aureus vaccines.

Gordon Y. C. Cheung & Michael Otto

doi: 10.1038/nature14083

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It takes three to find the exit p.29

Mitotic cell division separates chromosome pairs into two genetically identical daughter cells. A study in fission yeast reveals that this separation is guided by the sequential activation of three phosphatase enzymes. See Letter p.94

Mathieu Bollen

doi: 10.1038/nature14080

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Ocean circulation and rapid climate change p.30

High-resolution data on ocean circulation during the last glacial cycle suggest that the formation of North Atlantic Deep Water and associated heat transport may be more stable than previously thought. See Letter p.73

Ellen E. Martin

doi: 10.1038/nature14084

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Articles

RNA regulons in Hox 5′ UTRs confer ribosome specificity to gene regulation p.33

Specialized ribosomes (with a particular protein composition) carry out translation of specific transcripts; analysis of Hox mRNA translation in mice reveals that unique RNA structural elements within their 5′ UTRs, including internal ribosome entry sites and translation inhibitory elements, are responsible for this specialized mode of translation.

Shifeng Xue, Siqi Tian, Kotaro Fujii, Wipapat Kladwang, Rhiju Das & Maria Barna

doi: 10.1038/nature14010

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Architecture and conformational switch mechanism of the ryanodine receptor p.39

Using electron cryomicroscopy, the structure of the rabbit RyR1 calcium channel is determined at 6.1 Å resolution in the closed state and 8.5 Å in the open state, revealing how calcium binding to the EF-hand of RyR1 regulates channel opening and facilitates calcium-induced calcium release.

Rouslan G. Efremov, Alexander Leitner, Ruedi Aebersold & Stefan Raunser

doi: 10.1038/nature13916

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Structure of a mammalian ryanodine receptor p.44

Using electron cryomicroscopy, the closed-state structure of rabbit RyR1 is determined at 4.8 Å resolution; analysis confirms that the RyR1 architecture consists of a six-transmembrane ion channel with a cytosolic α-solenoid scaffold, and suggests a mechanism for Ca2+-induced channel opening.

Ran Zalk, Oliver B. Clarke, Amédée des Georges, Robert A. Grassucci, Steven Reiken, Filippo Mancia, Wayne A. Hendrickson, Joachim Frank & Andrew R. Marks

doi: 10.1038/nature13950

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Structure of the rabbit ryanodine receptor RyR1 at near-atomic resolution p.50

Using electron cryomicroscopy, the structure of the closed-state rabbit ryanodine receptor RyR1 in complex with its modulator FKBP12 is solved at 3.8 Å; in addition to determining structural details of the ion-conducting channel domain, three previously uncharacterized domains help to reveal a molecular scaffold that allows long-range allosteric regulation of channel activities.

Zhen Yan, Xiao-chen Bai, Chuangye Yan, Jianping Wu, Zhangqiang Li, Tian Xie, Wei Peng, Chang-cheng Yin, Xueming Li, Sjors H. W. Scheres + et al.

doi: 10.1038/nature14063

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Letters

A higher-than-predicted measurement of iron opacity at solar interior temperatures p.56

Laboratory measurements of iron opacity made under conditions similar to those inside the Sun reveal much higher opacity than predicted, helping to resolve inconsistencies within stellar models of the internal temperatures of stars.

J. E. Bailey, T. Nagayama, G. P. Loisel, G. A. Rochau, C. Blancard, J. Colgan, Ph. Cosse, G. Faussurier, C. J. Fontes, F. Gilleron + et al.

doi: 10.1038/nature14048

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Higher-than-predicted saltation threshold wind speeds on Titan p.60

Wind tunnel experiments designed to simulate the conditions on Saturn’s moon Titan yield threshold wind speeds for particle saltation higher than those predicted by models derived from simulations of terrestrial-planet conditions; the results can be reconciled by modifying the models to take into account the low ratio of particle density to fluid density on Titan.

Devon M. Burr, Nathan T. Bridges, John R. Marshall, James K. Smith, Bruce R. White & Joshua P. Emery

doi: 10.1038/nature14088

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Observation of quantized conductance in neutral matter p.64

Quantized conductance in the transport of neutral atoms is observed in an optically produced channel — either a quantum point contact or a quantum wire — between two atom reservoirs; the lowest non-zero conductance value is the universal conductance quantum, the reciprocal of Planck’s constant.

Sebastian Krinner, David Stadler, Dominik Husmann, Jean-Philippe Brantut & Tilman Esslinger

doi: 10.1038/nature14049

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An anisotropic hydrogel with electrostatic repulsion between cofacially aligned nanosheets p.68

Usually materials design focuses on attractive interactions, but here a hydrogel is described whose properties are dominated by electrostatic repulsion between negatively charged titanate nanosheets embedded within it; the material, inspired by articular cartilage, deforms easily when sheared parallel to the sheets but resists compressive forces applied orthogonally.

Mingjie Liu, Yasuhiro Ishida, Yasuo Ebina, Takayoshi Sasaki, Takaaki Hikima, Masaki Takata & Takuzo Aida

doi: 10.1038/nature14060

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Strong and deep Atlantic meridional overturning circulation during the last glacial cycle p.73

Reconstruction of the Atlantic meridional overturning circulation from a highly resolved marine sedimentary record shows that a deep, vigorous overturning circulation mode has persisted for most of the last glacial cycle, dominating ocean circulation in the Atlantic, but that a shallower glacial mode prevailed during glacial maxima.

E. Böhm, J. Lippold, M. Gutjahr, M. Frank, P. Blaser, B. Antz, J. Fohlmeister, N. Frank, M. B. Andersen & M. Deininger

doi: 10.1038/nature14059

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Origins of major archaeal clades correspond to gene acquisitions from bacteria p.77

A comparison of protein-coding genes from 134 archaeal genomes with their homologues in 1,847 bacterial genomes reveals that, during evolution, genes are transferred more often from bacteria to archaea than vice versa, and that gene influxes from bacteria can bring about the origin of major archaeal groups.

Shijulal Nelson-Sathi, Filipa L. Sousa, Mayo Roettger, Nabor Lozada-Chávez, Thorsten Thiergart, Arnold Janssen, David Bryant, Giddy Landan, Peter Schönheit, Bettina Siebers + et al.

doi: 10.1038/nature13805

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Hepatitis A virus and the origins of picornaviruses p.85

Hepatitis A virus is a picornavirus that causes significant morbidity but remains poorly understood; this paper now provides high-resolution crystal structures of both the mature and the empty hepatitis A virus particle, which show that the three-dimensional structure resembles insect picorna-like viruses.

Xiangxi Wang, Jingshan Ren, Qiang Gao, Zhongyu Hu, Yao Sun, Xuemei Li, David J. Rowlands, Weidong Yin, Junzhi Wang, David I. Stuart + et al.

doi: 10.1038/nature13806

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Human intracellular ISG15 prevents interferon-α/β over-amplification and auto-inflammation p.89

Intracellular ISG15 is an interferon (IFN)-α/β-inducible ubiquitin-like modifier which can covalently bind other proteins in a process called ISGylation; it is an effector of IFN-α/β-dependent antiviral immunity in mice. We previously published a study describing humans with inherited ISG15 deficiency but without unusually severe viral diseases. We showed that these patients were prone to mycobacterial disease and that human ISG15 was non-redundant as an extracellular IFN-γ-inducing molecule. We show here that ISG15-deficient patients also display unanticipated cellular, immunological and clinical signs of enhanced IFN-α/β immunity, reminiscent of the Mendelian autoinflammatory interferonopathies Aicardi–Goutières syndrome and spondyloenchondrodysplasia. We further show that an absence of intracellular ISG15 in the patients’ cells prevents the accumulation of USP18, a potent negative regulator of IFN-α/β signalling, resulting in the enhancement and amplification of IFN-α/β responses. Human ISG15, therefore, is not only redundant for antiviral immunity, but is a key negative regulator of IFN-α/β immunity. In humans, intracellular ISG15 is IFN-α/β-inducible not to serve as a substrate for ISGylation-dependent antiviral immunity, but to ensure USP18-dependent regulation of IFN-α/β and prevention of IFN-α/β-dependent autoinflammation.

Xianqin Zhang, Dusan Bogunovic, Béatrice Payelle-Brogard, Véronique Francois-Newton, Scott D. Speer, Chao Yuan, Stefano Volpi, Zhi Li, Ozden Sanal, Davood Mansouri + et al.

doi: 10.1038/nature13801

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A PP1–PP2A phosphatase relay controls mitotic progression p.94

The activation and coordination of phosphatase activity is important during mitotic exit; here, a mitotic phosphatase relay is described in fission yeast between the two major phosphatases, PP1 and PP2A, a mode of regulation that may be a feature of signalling networks across eukaryotes.

Agnes Grallert, Elvan Boke, Anja Hagting, Ben Hodgson, Yvonne Connolly, John R. Griffiths, Duncan L. Smith, Jonathon Pines & Iain M. Hagan

doi: 10.1038/nature14019

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Native structure of photosystem II at 1.95 Å resolution viewed by femtosecond X-ray pulses p.99

Photosynthesis converts light energy into biologically useful chemical energy vital to life on Earth. The initial reaction of photosynthesis takes place in photosystem II (PSII), a 700-kilodalton homodimeric membrane protein complex that catalyses photo-oxidation of water into dioxygen through an S-state cycle of the oxygen evolving complex (OEC). The structure of PSII has been solved by X-ray diffraction (XRD) at 1.9 ångström resolution, which revealed that the OEC is a Mn4CaO5-cluster coordinated by a well defined protein environment. However, extended X-ray absorption fine structure (EXAFS) studies showed that the manganese cations in the OEC are easily reduced by X-ray irradiation, and slight differences were found in the Mn–Mn distances determined by XRD, EXAFS and theoretical studies. Here we report a ‘radiation-damage-free’ structure of PSII from Thermosynechococcus vulcanus in the S1 state at a resolution of 1.95 ångströms using femtosecond X-ray pulses of the SPring-8 ångström compact free-electron laser (SACLA) and hundreds of large, highly isomorphous PSII crystals. Compared with the structure from XRD, the OEC in the X-ray free electron laser structure has Mn–Mn distances that are shorter by 0.1–0.2 ångströms. The valences of each manganese atom were tentatively assigned as Mn1D(iii), Mn2C(iv), Mn3B(iv) and Mn4A(iii), based on the average Mn–ligand distances and analysis of the Jahn–Teller axis on Mn(iii). One of the oxo-bridged oxygens, O5, has significantly longer distances to Mn than do the other oxo-oxygen atoms, suggesting that O5 is a hydroxide ion instead of a normal oxygen dianion and therefore may serve as one of the substrate oxygen atoms. These findings provide a structural basis for the mechanism of oxygen evolution, and we expect that this structure will provide a blueprint for the design of artificial catalysts for water oxidation.

Michihiro Suga, Fusamichi Akita, Kunio Hirata, Go Ueno, Hironori Murakami, Yoshiki Nakajima, Tetsuya Shimizu, Keitaro Yamashita, Masaki Yamamoto, Hideo Ago + et al.

doi: 10.1038/nature13991

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Structure of an integral membrane sterol reductase from Methylomicrobium alcaliphilum p.104

Sterols are essential biological molecules in the majority of life forms. Sterol reductases including Δ14-sterol reductase (C14SR, also known as TM7SF2), 7-dehydrocholesterol reductase (DHCR7) and 24-dehydrocholesterol reductase (DHCR24) reduce specific carbon–carbon double bonds of the sterol moiety using a reducing cofactor during sterol biosynthesis. Lamin B receptor (LBR), an integral inner nuclear membrane protein, also contains a functional C14SR domain. Here we report the crystal structure of a Δ14-sterol reductase (MaSR1) from the methanotrophic bacterium Methylomicrobium alcaliphilum 20Z (a homologue of human C14SR, LBR and DHCR7) with the cofactor NADPH. The enzyme contains ten transmembrane segments (TM1–10). Its catalytic domain comprises the carboxy-terminal half (containing TM6–10) and envelops two interconnected pockets, one of which faces the cytoplasm and houses NADPH, while the other one is accessible from the lipid bilayer. Comparison with a soluble steroid 5β-reductase structure suggests that the reducing end of NADPH meets the sterol substrate at the juncture of the two pockets. A sterol reductase activity assay proves that MaSR1 can reduce the double bond of a cholesterol biosynthetic intermediate, demonstrating functional conservation to human C14SR. Therefore, our structure as a prototype of integral membrane sterol reductases provides molecular insight into mutations in DHCR7 and LBR for inborn human diseases.

Xiaochun Li, Rita Roberti & Günter Blobel

doi: 10.1038/nature13797

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