TY - JOUR
AB - Flows through pipes and channels are, in practice, almost always turbulent, and the multiscale eddying motion is responsible for a major part of the encountered friction losses and pumping costs1. Conversely, for pulsatile flows, in particular for aortic blood flow, turbulence levels remain low despite relatively large peak velocities. For aortic blood flow, high turbulence levels are intolerable as they would damage the shear-sensitive endothelial cell layer2,3,4,5. Here we show that turbulence in ordinary pipe flow is diminished if the flow is driven in a pulsatile mode that incorporates all the key features of the cardiac waveform. At Reynolds numbers comparable to those of aortic blood flow, turbulence is largely inhibited, whereas at much higher speeds, the turbulent drag is reduced by more than 25%. This specific operation mode is more efficient when compared with steady driving, which is the present situation for virtually all fluid transport processes ranging from heating circuits to water, gas and oil pipelines.
AU - Scarselli, Davide
AU - Lopez Alonso, Jose M
AU - Varshney, Atul
AU - Hof, Björn
ID - 14341
IS - 7977
JF - Nature
SN - 0028-0836
TI - Turbulence suppression by cardiac-cycle-inspired driving of pipe flow
VL - 621
ER -
TY - JOUR
AB - Eukaryotic cells can undergo different forms of programmed cell death, many of which culminate in plasma membrane rupture as the defining terminal event1,2,3,4,5,6,7. Plasma membrane rupture was long thought to be driven by osmotic pressure, but it has recently been shown to be in many cases an active process, mediated by the protein ninjurin-18 (NINJ1). Here we resolve the structure of NINJ1 and the mechanism by which it ruptures membranes. Super-resolution microscopy reveals that NINJ1 clusters into structurally diverse assemblies in the membranes of dying cells, in particular large, filamentous assemblies with branched morphology. A cryo-electron microscopy structure of NINJ1 filaments shows a tightly packed fence-like array of transmembrane α-helices. Filament directionality and stability is defined by two amphipathic α-helices that interlink adjacent filament subunits. The NINJ1 filament features a hydrophilic side and a hydrophobic side, and molecular dynamics simulations show that it can stably cap membrane edges. The function of the resulting supramolecular arrangement was validated by site-directed mutagenesis. Our data thus suggest that, during lytic cell death, the extracellular α-helices of NINJ1 insert into the plasma membrane to polymerize NINJ1 monomers into amphipathic filaments that rupture the plasma membrane. The membrane protein NINJ1 is therefore an interactive component of the eukaryotic cell membrane that functions as an in-built breaking point in response to activation of cell death.
AU - Degen, Morris
AU - Santos, José Carlos
AU - Pluhackova, Kristyna
AU - Cebrero, Gonzalo
AU - Ramos, Saray
AU - Jankevicius, Gytis
AU - Hartenian, Ella
AU - Guillerm, Undina
AU - Mari, Stefania A.
AU - Kohl, Bastian
AU - Müller, Daniel J.
AU - Schanda, Paul
AU - Maier, Timm
AU - Perez, Camilo
AU - Sieben, Christian
AU - Broz, Petr
AU - Hiller, Sebastian
ID - 13096
JF - Nature
SN - 0028-0836
TI - Structural basis of NINJ1-mediated plasma membrane rupture in cell death
VL - 618
ER -
TY - JOUR
AB - A density wave (DW) is a fundamental type of long-range order in quantum matter tied to self-organization into a crystalline structure. The interplay of DW order with superfluidity can lead to complex scenarios that pose a great challenge to theoretical analysis. In the past decades, tunable quantum Fermi gases have served as model systems for exploring the physics of strongly interacting fermions, including most notably magnetic ordering1, pairing and superfluidity2, and the crossover from a Bardeen–Cooper–Schrieffer superfluid to a Bose–Einstein condensate3. Here, we realize a Fermi gas featuring both strong, tunable contact interactions and photon-mediated, spatially structured long-range interactions in a transversely driven high-finesse optical cavity. Above a critical long-range interaction strength, DW order is stabilized in the system, which we identify via its superradiant light-scattering properties. We quantitatively measure the variation of the onset of DW order as the contact interaction is varied across the Bardeen–Cooper–Schrieffer superfluid and Bose–Einstein condensate crossover, in qualitative agreement with a mean-field theory. The atomic DW susceptibility varies over an order of magnitude upon tuning the strength and the sign of the long-range interactions below the self-ordering threshold, demonstrating independent and simultaneous control over the contact and long-range interactions. Therefore, our experimental setup provides a fully tunable and microscopically controllable platform for the experimental study of the interplay of superfluidity and DW order.
AU - Helson, Victor
AU - Zwettler, Timo
AU - Mivehvar, Farokh
AU - Colella, Elvia
AU - Roux, Kevin Etienne Robert
AU - Konishi, Hideki
AU - Ritsch, Helmut
AU - Brantut, Jean Philippe
ID - 13119
JF - Nature
SN - 0028-0836
TI - Density-wave ordering in a unitary Fermi gas with photon-mediated interactions
VL - 618
ER -
TY - JOUR
AB - AbstractEndomembrane damage represents a form of stress that is detrimental for eukaryotic cells1,2. To cope with this threat, cells possess mechanisms that repair the damage and restore cellular homeostasis3–7. Endomembrane damage also results in organelle instability and the mechanisms by which cells stabilize damaged endomembranes to enable membrane repair remains unknown. Here, by combining in vitro and in cellulo studies with computational modelling we uncover a biological function for stress granules whereby these biomolecular condensates form rapidly at endomembrane damage sites and act as a plug that stabilizes the ruptured membrane. Functionally, we demonstrate that stress granule formation and membrane stabilization enable efficient repair of damaged endolysosomes, through both ESCRT (endosomal sorting complex required for transport)-dependent and independent mechanisms. We also show that blocking stress granule formation in human macrophages creates a permissive environment for Mycobacterium tuberculosis, a human pathogen that exploits endomembrane damage to survive within the host.
AU - Bussi, Claudio
AU - Mangiarotti, Agustín
AU - Vanhille-Campos, Christian Eduardo
AU - Aylan, Beren
AU - Pellegrino, Enrica
AU - Athanasiadi, Natalia
AU - Fearns, Antony
AU - Rodgers, Angela
AU - Franzmann, Titus M.
AU - Šarić, Anđela
AU - Dimova, Rumiana
AU - Gutierrez, Maximiliano G.
ID - 14610
JF - Nature
KW - Multidisciplinary
SN - 0028-0836
TI - Stress granules plug and stabilize damaged endolysosomal membranes
ER -
TY - JOUR
AB - The basic helix–loop–helix (bHLH) family of transcription factors recognizes DNA motifs known as E-boxes (CANNTG) and includes 108 members1. Here we investigate how chromatinized E-boxes are engaged by two structurally diverse bHLH proteins: the proto-oncogene MYC-MAX and the circadian transcription factor CLOCK-BMAL1 (refs. 2,3). Both transcription factors bind to E-boxes preferentially near the nucleosomal entry–exit sites. Structural studies with engineered or native nucleosome sequences show that MYC-MAX or CLOCK-BMAL1 triggers the release of DNA from histones to gain access. Atop the H2A–H2B acidic patch4, the CLOCK-BMAL1 Per-Arnt-Sim (PAS) dimerization domains engage the histone octamer disc. Binding of tandem E-boxes5–7 at endogenous DNA sequences occurs through direct interactions between two CLOCK-BMAL1 protomers and histones and is important for circadian cycling. At internal E-boxes, the MYC-MAX leucine zipper can also interact with histones H2B and H3, and its binding is indirectly enhanced by OCT4 elsewhere on the nucleosome. The nucleosomal E-box position and the type of bHLH dimerization domain jointly determine the histone contact, the affinity and the degree of competition and cooperativity with other nucleosome-bound factors.
AU - Michael, Alicia
AU - Stoos, Lisa
AU - Crosby, Priya
AU - Eggers, Nikolas
AU - Nie, Xinyu Y.
AU - Makasheva, Kristina
AU - Minnich, Martina
AU - Healy, Kelly L.
AU - Weiss, Joscha
AU - Kempf, Georg
AU - Cavadini, Simone
AU - Kater, Lukas
AU - Seebacher, Jan
AU - Vecchia, Luca
AU - Chakraborty, Deyasini
AU - Isbel, Luke
AU - Grand, Ralph S.
AU - Andersch, Florian
AU - Fribourgh, Jennifer L.
AU - Schübeler, Dirk
AU - Zuber, Johannes
AU - Liu, Andrew C.
AU - Becker, Peter B.
AU - Fierz, Beat
AU - Partch, Carrie L.
AU - Menet, Jerome S.
AU - Thomä, Nicolas H.
ID - 15148
IS - 7969
JF - Nature
SN - 0028-0836
TI - Cooperation between bHLH transcription factors and histones for DNA access
VL - 619
ER -
TY - JOUR
AB - Sperm chromatin is typically transformed by protamines into a compact and transcriptionally inactive state1,2. Sperm cells of flowering plants lack protamines, yet they have small, transcriptionally active nuclei with chromatin condensed through an unknown mechanism3,4. Here we show that a histone variant, H2B.8, mediates sperm chromatin and nuclear condensation in Arabidopsis thaliana. Loss of H2B.8 causes enlarged sperm nuclei with dispersed chromatin, whereas ectopic expression in somatic cells produces smaller nuclei with aggregated chromatin. This result demonstrates that H2B.8 is sufficient for chromatin condensation. H2B.8 aggregates transcriptionally inactive AT-rich chromatin into phase-separated condensates, which facilitates nuclear compaction without reducing transcription. Reciprocal crosses show that mutation of h2b.8 reduces male transmission, which suggests that H2B.8-mediated sperm compaction is important for fertility. Altogether, our results reveal a new mechanism of nuclear compaction through global aggregation of unexpressed chromatin. We propose that H2B.8 is an evolutionary innovation of flowering plants that achieves nuclear condensation compatible with active transcription.
AU - Buttress, Toby
AU - He, Shengbo
AU - Wang, Liang
AU - Zhou, Shaoli
AU - Saalbach, Gerhard
AU - Vickers, Martin
AU - Li, Guohong
AU - Li, Pilong
AU - Feng, Xiaoqi
ID - 12671
IS - 7936
JF - Nature
SN - 0028-0836
TI - Histone H2B.8 compacts flowering plant sperm through chromatin phase separation
VL - 611
ER -
TY - JOUR
AB - Intragenic regions that are removed during maturation of the RNA transcript—introns—are universally present in the nuclear genomes of eukaryotes1. The budding yeast, an otherwise intron-poor species, preserves two sets of ribosomal protein genes that differ primarily in their introns2,3. Although studies have shed light on the role of ribosomal protein introns under stress and starvation4,5,6, understanding the contribution of introns to ribosome regulation remains challenging. Here, by combining isogrowth profiling7 with single-cell protein measurements8, we show that introns can mediate inducible phenotypic heterogeneity that confers a clear fitness advantage. Osmotic stress leads to bimodal expression of the small ribosomal subunit protein Rps22B, which is mediated by an intron in the 5′ untranslated region of its transcript. The two resulting yeast subpopulations differ in their ability to cope with starvation. Low levels of Rps22B protein result in prolonged survival under sustained starvation, whereas high levels of Rps22B enable cells to grow faster after transient starvation. Furthermore, yeasts growing at high concentrations of sugar, similar to those in ripe grapes, exhibit bimodal expression of Rps22B when approaching the stationary phase. Differential intron-mediated regulation of ribosomal protein genes thus provides a way to diversify the population when starvation threatens in natural environments. Our findings reveal a role for introns in inducing phenotypic heterogeneity in changing environments, and suggest that duplicated ribosomal protein genes in yeast contribute to resolving the evolutionary conflict between precise expression control and environmental responsiveness9.
AU - Lukacisin, Martin
AU - Espinosa-Cantú, Adriana
AU - Bollenbach, Mark Tobias
ID - 11341
JF - Nature
SN - 0028-0836
TI - Intron-mediated induction of phenotypic heterogeneity
VL - 605
ER -
TY - JOUR
AB - Polar auxin transport is unique to plants and coordinates their growth and development1,2. The PIN-FORMED (PIN) auxin transporters exhibit highly asymmetrical localizations at the plasma membrane and drive polar auxin transport3,4; however, their structures and transport mechanisms remain largely unknown. Here, we report three inward-facing conformation structures of Arabidopsis thaliana PIN1: the apo state, bound to the natural auxin indole-3-acetic acid (IAA), and in complex with the polar auxin transport inhibitor N-1-naphthylphthalamic acid (NPA). The transmembrane domain of PIN1 shares a conserved NhaA fold5. In the substrate-bound structure, IAA is coordinated by both hydrophobic stacking and hydrogen bonding. NPA competes with IAA for the same site at the intracellular pocket, but with a much higher affinity. These findings inform our understanding of the substrate recognition and transport mechanisms of PINs and set up a framework for future research on directional auxin transport, one of the most crucial processes underlying plant development.
AU - Yang, Z
AU - Xia, J
AU - Hong, J
AU - Zhang, C
AU - Wei, H
AU - Ying, W
AU - Sun, C
AU - Sun, L
AU - Mao, Y
AU - Gao, Y
AU - Tan, S
AU - Friml, Jiří
AU - Li, D
AU - Liu, X
AU - Sun, L
ID - 12054
IS - 7927
JF - Nature
SN - 0028-0836
TI - Structural insights into auxin recognition and efflux by Arabidopsis PIN1
VL - 609
ER -
TY - JOUR
AB - Complex I is the first enzyme in the respiratory chain, which is responsible for energy production in mitochondria and bacteria1. Complex I couples the transfer of two electrons from NADH to quinone and the translocation of four protons across the membrane2, but the coupling mechanism remains contentious. Here we present cryo-electron microscopy structures of Escherichia coli complex I (EcCI) in different redox states, including catalytic turnover. EcCI exists mostly in the open state, in which the quinone cavity is exposed to the cytosol, allowing access for water molecules, which enable quinone movements. Unlike the mammalian paralogues3, EcCI can convert to the closed state only during turnover, showing that closed and open states are genuine turnover intermediates. The open-to-closed transition results in the tightly engulfed quinone cavity being connected to the central axis of the membrane arm, a source of substrate protons. Consistently, the proportion of the closed state increases with increasing pH. We propose a detailed but straightforward and robust mechanism comprising a ‘domino effect’ series of proton transfers and electrostatic interactions: the forward wave (‘dominoes stacking’) primes the pump, and the reverse wave (‘dominoes falling’) results in the ejection of all pumped protons from the distal subunit NuoL. This mechanism explains why protons exit exclusively from the NuoL subunit and is supported by our mutagenesis data. We contend that this is a universal coupling mechanism of complex I and related enzymes.
AU - Kravchuk, Vladyslav
AU - Petrova, Olga
AU - Kampjut, Domen
AU - Wojciechowska-Bason, Anna
AU - Breese, Zara
AU - Sazanov, Leonid A
ID - 12138
IS - 7928
JF - Nature
KW - Multidisciplinary
SN - 0028-0836
TI - A universal coupling mechanism of respiratory complex I
VL - 609
ER -
TY - JOUR
AB - The morphology and functionality of the epithelial lining differ along the intestinal tract, but tissue renewal at all sites is driven by stem cells at the base of crypts1,2,3. Whether stem cell numbers and behaviour vary at different sites is unknown. Here we show using intravital microscopy that, despite similarities in the number and distribution of proliferative cells with an Lgr5 signature in mice, small intestinal crypts contain twice as many effective stem cells as large intestinal crypts. We find that, although passively displaced by a conveyor-belt-like upward movement, small intestinal cells positioned away from the crypt base can function as long-term effective stem cells owing to Wnt-dependent retrograde cellular movement. By contrast, the near absence of retrograde movement in the large intestine restricts cell repositioning, leading to a reduction in effective stem cell number. Moreover, after suppression of the retrograde movement in the small intestine, the number of effective stem cells is reduced, and the rate of monoclonal conversion of crypts is accelerated. Together, these results show that the number of effective stem cells is determined by active retrograde movement, revealing a new channel of stem cell regulation that can be experimentally and pharmacologically manipulated.
AU - Azkanaz, Maria
AU - Corominas-Murtra, Bernat
AU - Ellenbroek, Saskia I. J.
AU - Bruens, Lotte
AU - Webb, Anna T.
AU - Laskaris, Dimitrios
AU - Oost, Koen C.
AU - Lafirenze, Simona J. A.
AU - Annusver, Karl
AU - Messal, Hendrik A.
AU - Iqbal, Sharif
AU - Flanagan, Dustin J.
AU - Huels, David J.
AU - Rojas-Rodríguez, Felipe
AU - Vizoso, Miguel
AU - Kasper, Maria
AU - Sansom, Owen J.
AU - Snippert, Hugo J.
AU - Liberali, Prisca
AU - Simons, Benjamin D.
AU - Katajisto, Pekka
AU - Hannezo, Edouard B
AU - van Rheenen, Jacco
ID - 12274
IS - 7919
JF - Nature
KW - Multidisciplinary
SN - 0028-0836
TI - Retrograde movements determine effective stem cell numbers in the intestine
VL - 607
ER -
TY - JOUR
AB - The phytohormone auxin is the major coordinative signal in plant development1, mediating transcriptional reprogramming by a well-established canonical signalling pathway. TRANSPORT INHIBITOR RESPONSE 1 (TIR1)/AUXIN-SIGNALING F-BOX (AFB) auxin receptors are F-box subunits of ubiquitin ligase complexes. In response to auxin, they associate with Aux/IAA transcriptional repressors and target them for degradation via ubiquitination2,3. Here we identify adenylate cyclase (AC) activity as an additional function of TIR1/AFB receptors across land plants. Auxin, together with Aux/IAAs, stimulates cAMP production. Three separate mutations in the AC motif of the TIR1 C-terminal region, all of which abolish the AC activity, each render TIR1 ineffective in mediating gravitropism and sustained auxin-induced root growth inhibition, and also affect auxin-induced transcriptional regulation. These results highlight the importance of TIR1/AFB AC activity in canonical auxin signalling. They also identify a unique phytohormone receptor cassette combining F-box and AC motifs, and the role of cAMP as a second messenger in plants.
AU - Qi, Linlin
AU - Kwiatkowski, Mateusz
AU - Chen, Huihuang
AU - Hörmayer, Lukas
AU - Sinclair, Scott A
AU - Zou, Minxia
AU - del Genio, Charo I.
AU - Kubeš, Martin F.
AU - Napier, Richard
AU - Jaworski, Krzysztof
AU - Friml, Jiří
ID - 12144
IS - 7934
JF - Nature
SN - 0028-0836
TI - Adenylate cyclase activity of TIR1/AFB auxin receptors in plants
VL - 611
ER -
TY - JOUR
AB - Future LEDs could be based on lead halide perovskites. A breakthrough in preparing device-compatible solids composed of nanoscale perovskite crystals overcomes a long-standing hurdle in making blue perovskite LEDs.
AU - Utzat, Hendrik
AU - Ibáñez, Maria
ID - 14437
IS - 7941
JF - Nature
KW - Multidisciplinary
SN - 0028-0836
TI - Molecular engineering enables bright blue LEDs
VL - 612
ER -
TY - JOUR
AB - The phytohormone auxin triggers transcriptional reprogramming through a well-characterized perception machinery in the nucleus. By contrast, mechanisms that underlie fast effects of auxin, such as the regulation of ion fluxes, rapid phosphorylation of proteins or auxin feedback on its transport, remain unclear1,2,3. Whether auxin-binding protein 1 (ABP1) is an auxin receptor has been a source of debate for decades1,4. Here we show that a fraction of Arabidopsis thaliana ABP1 is secreted and binds auxin specifically at an acidic pH that is typical of the apoplast. ABP1 and its plasma-membrane-localized partner, transmembrane kinase 1 (TMK1), are required for the auxin-induced ultrafast global phospho-response and for downstream processes that include the activation of H+-ATPase and accelerated cytoplasmic streaming. abp1 and tmk mutants cannot establish auxin-transporting channels and show defective auxin-induced vasculature formation and regeneration. An ABP1(M2X) variant that lacks the capacity to bind auxin is unable to complement these defects in abp1 mutants. These data indicate that ABP1 is the auxin receptor for TMK1-based cell-surface signalling, which mediates the global phospho-response and auxin canalization.
AU - Friml, Jiří
AU - Gallei, Michelle C
AU - Gelová, Zuzana
AU - Johnson, Alexander J
AU - Mazur, Ewa
AU - Monzer, Aline
AU - Rodriguez Solovey, Lesia
AU - Roosjen, Mark
AU - Verstraeten, Inge
AU - Živanović, Branka D.
AU - Zou, Minxia
AU - Fiedler, Lukas
AU - Giannini, Caterina
AU - Grones, Peter
AU - Hrtyan, Mónika
AU - Kaufmann, Walter
AU - Kuhn, Andre
AU - Narasimhan, Madhumitha
AU - Randuch, Marek
AU - Rýdza, Nikola
AU - Takahashi, Koji
AU - Tan, Shutang
AU - Teplova, Anastasiia
AU - Kinoshita, Toshinori
AU - Weijers, Dolf
AU - Rakusová, Hana
ID - 12291
IS - 7927
JF - Nature
SN - 0028-0836
TI - ABP1–TMK auxin perception for global phosphorylation and auxin canalization
VL - 609
ER -
TY - JOUR
AB - Hybrid semiconductor–superconductor devices hold great promise for realizing topological quantum computing with Majorana zero modes1,2,3,4,5. However, multiple claims of Majorana detection, based on either tunnelling6,7,8,9,10 or Coulomb blockade (CB) spectroscopy11,12, remain disputed. Here we devise an experimental protocol that allows us to perform both types of measurement on the same hybrid island by adjusting its charging energy via tunable junctions to the normal leads. This method reduces ambiguities of Majorana detections by checking the consistency between CB spectroscopy and zero-bias peaks in non-blockaded transport. Specifically, we observe junction-dependent, even–odd modulated, single-electron CB peaks in InAs/Al hybrid nanowires without concomitant low-bias peaks in tunnelling spectroscopy. We provide a theoretical interpretation of the experimental observations in terms of low-energy, longitudinally confined island states rather than overlapping Majorana modes. Our results highlight the importance of combined measurements on the same device for the identification of topological Majorana zero modes.
AU - Valentini, Marco
AU - Borovkov, Maksim
AU - Prada, Elsa
AU - Martí-Sánchez, Sara
AU - Botifoll, Marc
AU - Hofmann, Andrea C
AU - Arbiol, Jordi
AU - Aguado, Ramón
AU - San-Jose, Pablo
AU - Katsaros, Georgios
ID - 12118
IS - 7940
JF - Nature
KW - Multidisciplinary
SN - 0028-0836
TI - Majorana-like Coulomb spectroscopy in the absence of zero-bias peaks
VL - 612
ER -
TY - JOUR
AB - AMPA receptors (AMPARs) mediate the majority of excitatory transmission in the brain and enable the synaptic plasticity that underlies learning1. A diverse array of AMPAR signalling complexes are established by receptor auxiliary subunits, which associate with the AMPAR in various combinations to modulate trafficking, gating and synaptic strength2. However, their mechanisms of action are poorly understood. Here we determine cryo-electron microscopy structures of the heteromeric GluA1–GluA2 receptor assembled with both TARP-γ8 and CNIH2, the predominant AMPAR complex in the forebrain, in both resting and active states. Two TARP-γ8 and two CNIH2 subunits insert at distinct sites beneath the ligand-binding domains of the receptor, with site-specific lipids shaping each interaction and affecting the gating regulation of the AMPARs. Activation of the receptor leads to asymmetry between GluA1 and GluA2 along the ion conduction path and an outward expansion of the channel triggers counter-rotations of both auxiliary subunit pairs, promoting the active-state conformation. In addition, both TARP-γ8 and CNIH2 pivot towards the pore exit upon activation, extending their reach for cytoplasmic receptor elements. CNIH2 achieves this through its uniquely extended M2 helix, which has transformed this endoplasmic reticulum-export factor into a powerful AMPAR modulator that is capable of providing hippocampal pyramidal neurons with their integrative synaptic properties.
AU - Zhang, Danyang
AU - Watson, Jake
AU - Matthews, Peter M.
AU - Cais, Ondrej
AU - Greger, Ingo H.
ID - 9549
JF - Nature
SN - 0028-0836
TI - Gating and modulation of a hetero-octameric AMPA glutamate receptor
VL - 594
ER -
TY - JOUR
AB - Ferromagnetism is most common in transition metal compounds but may also arise in low-density two-dimensional electron systems, with signatures observed in silicon, III-V semiconductor systems, and graphene moiré heterostructures. Here we show that gate-tuned van Hove singularities in rhombohedral trilayer graphene drive the spontaneous ferromagnetic polarization of the electron system into one or more spin- and valley flavors. Using capacitance measurements on graphite-gated van der Waals heterostructures, we find a cascade of density- and electronic displacement field tuned phase transitions marked by negative electronic compressibility. The transitions define the boundaries between phases where quantum oscillations have either four-fold, two-fold, or one-fold degeneracy, associated with a spin and valley degenerate normal metal, spin-polarized `half-metal', and spin and valley polarized `quarter metal', respectively. For electron doping, the salient features are well captured by a phenomenological Stoner model with a valley-anisotropic Hund's coupling, likely arising from interactions at the lattice scale. For hole filling, we observe a richer phase diagram featuring a delicate interplay of broken symmetries and transitions in the Fermi surface topology. Finally, by rotational alignment of a hexagonal boron nitride substrate to induce a moiré superlattice, we find that the superlattice perturbs the preexisting isospin order only weakly, leaving the basic phase diagram intact while catalyzing the formation of topologically nontrivial gapped states whenever itinerant half- or quarter metal states occur at half- or quarter superlattice band filling. Our results show that rhombohedral trilayer graphene is an ideal platform for well-controlled tests of many-body theory and reveal magnetism in moiré materials to be fundamentally itinerant in nature.
AU - Zhou, Haoxin
AU - Xie, Tian
AU - Ghazaryan, Areg
AU - Holder, Tobias
AU - Ehrets, James R.
AU - Spanton, Eric M.
AU - Taniguchi, Takashi
AU - Watanabe, Kenji
AU - Berg, Erez
AU - Serbyn, Maksym
AU - Young, Andrea F.
ID - 10025
JF - Nature
KW - condensed matter - mesoscale and nanoscale physics
KW - condensed matter - strongly correlated electrons
KW - multidisciplinary
SN - 0028-0836
TI - Half and quarter metals in rhombohedral trilayer graphene
ER -
TY - JOUR
AB - The enzymes of the mitochondrial electron transport chain are key players of cell metabolism. Despite being active when isolated, in vivo they associate into supercomplexes1, whose precise role is debated. Supercomplexes CIII2CIV1-2 (refs. 2,3), CICIII2 (ref. 4) and CICIII2CIV (respirasome)5,6,7,8,9,10 exist in mammals, but in contrast to CICIII2 and the respirasome, to date the only known eukaryotic structures of CIII2CIV1-2 come from Saccharomyces cerevisiae11,12 and plants13, which have different organization. Here we present the first, to our knowledge, structures of mammalian (mouse and ovine) CIII2CIV and its assembly intermediates, in different conformations. We describe the assembly of CIII2CIV from the CIII2 precursor to the final CIII2CIV conformation, driven by the insertion of the N terminus of the assembly factor SCAF1 (ref. 14) deep into CIII2, while its C terminus is integrated into CIV. Our structures (which include CICIII2 and the respirasome) also confirm that SCAF1 is exclusively required for the assembly of CIII2CIV and has no role in the assembly of the respirasome. We show that CIII2 is asymmetric due to the presence of only one copy of subunit 9, which straddles both monomers and prevents the attachment of a second copy of SCAF1 to CIII2, explaining the presence of one copy of CIV in CIII2CIV in mammals. Finally, we show that CIII2 and CIV gain catalytic advantage when assembled into the supercomplex and propose a role for CIII2CIV in fine tuning the efficiency of electron transfer in the electron transport chain.
AU - Vercellino, Irene
AU - Sazanov, Leonid A
ID - 10146
IS - 7880
JF - Nature
SN - 0028-0836
TI - Structure and assembly of the mammalian mitochondrial supercomplex CIII2CIV
VL - 598
ER -
TY - JOUR
AB - The majority of gene transcripts generated by RNA polymerase II in mammalian genomes initiate at CpG island (CGI) promoters1,2, yet our understanding of their regulation remains limited. This is in part due to the incomplete information that we have on transcription factors, their DNA-binding motifs and which genomic binding sites are functional in any given cell type3,4,5. In addition, there are orphan motifs without known binders, such as the CGCG element, which is associated with highly expressed genes across human tissues and enriched near the transcription start site of a subset of CGI promoters6,7,8. Here we combine single-molecule footprinting with interaction proteomics to identify BTG3-associated nuclear protein (BANP) as the transcription factor that binds this element in the mouse and human genome. We show that BANP is a strong CGI activator that controls essential metabolic genes in pluripotent stem and terminally differentiated neuronal cells. BANP binding is repelled by DNA methylation of its motif in vitro and in vivo, which epigenetically restricts most binding to CGIs and accounts for differential binding at aberrantly methylated CGI promoters in cancer cells. Upon binding to an unmethylated motif, BANP opens chromatin and phases nucleosomes. These findings establish BANP as a critical activator of a set of essential genes and suggest a model in which the activity of CGI promoters relies on methylation-sensitive transcription factors that are capable of chromatin opening.
AU - Grand, Ralph S.
AU - Burger, Lukas
AU - Gräwe, Cathrin
AU - Michael, Alicia
AU - Isbel, Luke
AU - Hess, Daniel
AU - Hoerner, Leslie
AU - Iesmantavicius, Vytautas
AU - Durdu, Sevi
AU - Pregnolato, Marco
AU - Krebs, Arnaud R.
AU - Smallwood, Sébastien A.
AU - Thomä, Nicolas
AU - Vermeulen, Michiel
AU - Schübeler, Dirk
ID - 15150
JF - Nature
SN - 0028-0836
TI - BANP opens chromatin and activates CpG-island-regulated genes
VL - 596
ER -
TY - JOUR
AB - Magnetism typically arises from the joint effect of Fermi statistics and repulsive Coulomb interactions, which favours ground states with non-zero electron spin. As a result, controlling spin magnetism with electric fields—a longstanding technological goal in spintronics and multiferroics1,2—can be achieved only indirectly. Here we experimentally demonstrate direct electric-field control of magnetic states in an orbital Chern insulator3,4,5,6, a magnetic system in which non-trivial band topology favours long-range order of orbital angular momentum but the spins are thought to remain disordered7,8,9,10,11,12,13,14. We use van der Waals heterostructures consisting of a graphene monolayer rotationally faulted with respect to a Bernal-stacked bilayer to realize narrow and topologically non-trivial valley-projected moiré minibands15,16,17. At fillings of one and three electrons per moiré unit cell within these bands, we observe quantized anomalous Hall effects18 with transverse resistance approximately equal to h/2e2 (where h is Planck’s constant and e is the charge on the electron), which is indicative of spontaneous polarization of the system into a single-valley-projected band with a Chern number equal to two. At a filling of three electrons per moiré unit cell, we find that the sign of the quantum anomalous Hall effect can be reversed via field-effect control of the chemical potential; moreover, this transition is hysteretic, which we use to demonstrate non-volatile electric-field-induced reversal of the magnetic state. A theoretical analysis19 indicates that the effect arises from the topological edge states, which drive a change in sign of the magnetization and thus a reversal in the favoured magnetic state. Voltage control of magnetic states can be used to electrically pattern non-volatile magnetic-domain structures hosting chiral edge states, with applications ranging from reconfigurable microwave circuit elements to ultralow-power magnetic memories.
AU - Polshyn, Hryhoriy
AU - Zhu, J.
AU - Kumar, M. A.
AU - Zhang, Y.
AU - Yang, F.
AU - Tschirhart, C. L.
AU - Serlin, M.
AU - Watanabe, K.
AU - Taniguchi, T.
AU - MacDonald, A. H.
AU - Young, A. F.
ID - 10618
IS - 7836
JF - Nature
KW - multidisciplinary
SN - 0028-0836
TI - Electrical switching of magnetic order in an orbital Chern insulator
VL - 588
ER -
TY - JOUR
AB - From rock salt to nanoparticle superlattices, complex structure can emerge from simple building blocks that attract each other through Coulombic forces1-4. On the micrometre scale, however, colloids in water defy the intuitively simple idea of forming crystals from oppositely charged partners, instead forming non-equilibrium structures such as clusters and gels5-7. Although various systems have been engineered to grow binary crystals8-11, native surface charge in aqueous conditions has not been used to assemble crystalline materials. Here we form ionic colloidal crystals in water through an approach that we refer to as polymer-attenuated Coulombic self-assembly. The key to crystallization is the use of a neutral polymer to keep particles separated by well defined distances, allowing us to tune the attractive overlap of electrical double layers, directing particles to disperse, crystallize or become permanently fixed on demand. The nucleation and growth of macroscopic single crystals is demonstrated by using the Debye screening length to fine-tune assembly. Using a variety of colloidal particles and commercial polymers, ionic colloidal crystals isostructural to caesium chloride, sodium chloride, aluminium diboride and K4C60 are selected according to particle size ratios. Once fixed by simply diluting out solution salts, crystals are pulled out of the water for further manipulation, demonstrating an accurate translation from solution-phase assembly to dried solid structures. In contrast to other assembly approaches, in which particles must be carefully engineered to encode binding information12-18, polymer-attenuated Coulombic self-assembly enables conventional colloids to be used as model colloidal ions, primed for crystallization.
AU - Hueckel, Theodore
AU - Hocky, Glen M.
AU - Palacci, Jérémie A
AU - Sacanna, Stefano
ID - 9059
IS - 7804
JF - Nature
KW - Multidisciplinary
SN - 0028-0836
TI - Ionic solids from common colloids
VL - 580
ER -