Science
30 Sep 2022
Volume 377 | Issue 6614
Research - Research Articles
1. Aqueously altered igneous rocks sampled on the floor of Jezero crater, Mars 
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First/Corresponding author:
K.A. Farley
Affiliation:
Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA.
Abstract:
The Perseverance rover landed in Jezero crater, Mars, to investigate ancient lake and river deposits. We report observations of the crater floor, below the crater’s sedimentary delta, finding that the floor consists of igneous rocks altered by water. The lowest exposed unit, informally named Séítah, is a coarsely crystalline olivine-rich rock, which accumulated at the base of a magma body. Magnesium-iron carbonates along grain boundaries indicate reactions with carbon dioxide–rich water under water-poor conditions. Overlying Séítah is a unit informally named Máaz, which we interpret as lava flows or the chemical complement to Séítah in a layered igneous body. Voids in these rocks contain sulfates and perchlorates, likely introduced by later near-surface brine evaporation. Core samples of these rocks have been stored aboard Perseverance for potential return to Earth.
2. Oncometabolite D-2HG alters T cell metabolism to impair CD8+ T cell function 下载原文
First author:
Giulia Notarangelo①
Corresponding author:
Marcia C. Haigis②
Affiliation:
Department of Cell Biology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA.①②
Abstract:
Gain-of-function mutations in isocitrate dehydrogenase (IDH) in human cancers result in the production of d-2-hydroxyglutarate (d-2HG), an oncometabolite that promotes tumorigenesis through epigenetic alterations. The cancer cell–intrinsic effects of d-2HG are well understood, but its tumor cell–nonautonomous roles remain poorly explored. We compared the oncometabolite d-2HG with its enantiomer, l-2HG, and found that tumor-derived d-2HG was taken up by CD8+ T cells and altered their metabolism and antitumor functions in an acute and reversible fashion. We identified the glycolytic enzyme lactate dehydrogenase (LDH) as a molecular target of d-2HG. d-2HG and inhibition of LDH drive a metabolic program and immune CD8+ T cell signature marked by decreased cytotoxicity and impaired interferon-γ signaling that was recapitulated in clinical samples from human patients with IDH1 mutant gliomas.
3. Cyclic ADP ribose isomers: Production, chemical structures, and immune signaling 下载原文
First author:
Mohammad K. Manik①
Corresponding authors: Thomas Ve*②, Bostjan Kobe③
Affiliations:
School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia.①③
Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD 4072, Australia.①③
Institute for Glycomics, Griffith University, Southport, QLD 4222, Australia. ②
The University of Queensland, Institute for Molecular Bioscience, Brisbane, QLD 4072, Australia.③
Abstract:
Cyclic adenosine diphosphate (ADP)–ribose (cADPR) isomers are signaling molecules produced by bacterial and plant Toll/interleukin-1 receptor (TIR) domains via nicotinamide adenine dinucleotide (oxidized form) (NAD+) hydrolysis. We show that v-cADPR (2′cADPR) and v2-cADPR (3′cADPR) isomers are cyclized by O-glycosidic bond formation between the ribose moieties in ADPR. Structures of 2′cADPR-producing TIR domains reveal conformational changes that lead to an active assembly that resembles those of Toll-like receptor adaptor TIR domains. Mutagenesis reveals a conserved tryptophan that is essential for cyclization. We show that 3′cADPR is an activator of ThsA effector proteins from the bacterial antiphage defense system termed Thoeris and a suppressor of plant immunity when produced by the effector HopAM1. Collectively, our results reveal the molecular basis of cADPR isomer production and establish 3′cADPR in bacteria as an antiviral and plant immunity–suppressing signaling molecule.
Reports
1. Actin maturation requires the ACTMAP/C19orf54 protease 下载原文
First author:
Peter Haahr①
Corresponding author:
Thijn R. Brummelkamp②
Affiliations:
Division of Biochemistry, Netherlands Cancer Institute, 1066CX Amsterdam, Netherlands.①②
Novo Nordisk Foundation Center for Protein Research (NNF-CPR), Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark.①
Abstract:
Protein synthesis generally starts with a methionine that is removed during translation. However, cytoplasmic actin defies this rule because its synthesis involves noncanonical excision of the acetylated methionine by an unidentified enzyme after translation. Here, we identified C19orf54, named ACTMAP (actin maturation protease), as this enzyme. Its ablation resulted in viable mice in which the cytoskeleton was composed of immature actin molecules across all tissues. However, in skeletal muscle, the lengths of sarcomeric actin filaments were shorter, muscle function was decreased, and centralized nuclei, a common hallmark of myopathies, progressively accumulated. Thus, ACTMAP encodes the missing factor required for the synthesis of mature actin and regulates specific actin-dependent traits in vivo.
2. Promotion of superconductivity in magic-angle graphene multilayers 下载原文
First author:
Yiran Zhang①
Corresponding author:
Stevan Nadj-Perge②
Affiliations:
T. J. Watson Laboratory of Applied Physics, California Institute of Technology, Pasadena, CA 91125, USA.①②
Institute for Quantum Information and Matter, Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA.①②
Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA.①
Abstract:
Graphene moiré superlattices show an abundance of correlated insulating, topological, and superconducting phases. Whereas the origins of strong correlations and nontrivial topology can be directly linked to flat bands, the nature of superconductivity remains enigmatic. We demonstrate that magic-angle devices made of twisted tri-, quadri-, and pentalayer graphene placed on monolayer tungsten diselenide exhibit flavor polarization and superconductivity. We also observe insulating states in the tril- and quadrilayer arising at finite electric displacement fields. As the number of layers increases, superconductivity emerges over an enhanced filling-factor range, and in the pentalayer it extends well beyond the filling of four electrons per moiré unit cell. Our results highlight the role of the interplay between flat and more dispersive bands in extending superconducting regions in graphene moiré superlattices.
3. Hydrophobic polyamide nanofilms provide rapid transport for crude oil separation 下载原文
First author:
Siyao Li①
Corresponding authors:
Zhiwei Jiang②, Andrew G.Livingston③
Affiliations:
Barrer Center, DepartmenAbstractt of Chemical Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.①②③
School of Engineering and Materials Science, Queen Mary University of London, London E1 4NS, UK.②③
Abstract:
Hydrocarbon separation relies on energy-intensive distillation. Membrane technology can offer an energy-efficient alternative but requires selective differentiation of crude oil molecules with rapid liquid transport. We synthesized multiblock oligomer amines, which comprised a central amine segment with two hydrophobic oligomer blocks, and used them to fabricate hydrophobic polyamide nanofilms by interfacial polymerization from self-assembled vesicles. These polyamide nanofilms provide transport of hydrophobic liquids more than 100 times faster than that of conventional hydrophilic counterparts. In the fractionation of light crude oil, manipulation of the film thickness down to ~10 nanometers achieves permeance one order of magnitude higher than that of current state-of-the-art hydrophobic membranes while retaining comparable size- and class-based separation. This high permeance can markedly reduce plant footprint, which expands the potential for using membranes made of ultrathin nanofilms in crude oil fractionation.
4. Catalytic deconstruction of waste polyethylene with ethylene to form propylene 下载原文
First author:
Richard J. Conk①
Corresponding author:
John F. Hartwig②
Affiliation:
Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA.①②
Abstract:
The conversion of polyolefins to monomers would create a valuable carbon feedstock from the largest fraction of waste plastic. However, breakdown of the main chains in these polymers requires the cleavage of carbon–carbon bonds that tend to resist selective chemical transformations. Here, we report the production of propylene by partial dehydrogenation of polyethylene and tandem isomerizing ethenolysis of the desaturated chain. Dehydrogenation of high-density polyethylene with either an iridium-pincer complex or platinum/zinc supported on silica as catalysts yielded dehydrogenated material containing up to 3.2% internal olefins; the combination of a second-generation Hoveyda-Grubbs metathesis catalyst and [PdP(tBu)3(μ-Br)]2 as an isomerization catalyst selectively degraded this unsaturated polymer to propylene in yields exceeding 80%. These results show promise for the application of mild catalysis to deconstruct otherwise stable polyolefins.
5. Inefficient and unlit natural gas flares both emit large quantities of methane 下载原文
First author:
Genevieve Plant①
Corresponding author:
Eric A. Kort②
Affiliation:
Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI, USA.①②
Abstract:
Flaring is widely used by the fossil fuel industry to dispose of natural gas. Industry and governments generally assume that flares remain lit and destroy methane, the predominant component of natural gas, with 98% efficiency. Neither assumption, however, is based on real-world observations. We calculate flare efficiency using airborne sampling across three basins responsible for >80% of US flaring and combine these observations with unlit flare prevalence surveys. We find that both unlit flares and inefficient combustion contribute comparably to ineffective methane destruction, with flares effectively destroying only 91.1% (90.2, 91.8; 95% confidence interval) of methane. This represents a fivefold increase in methane emissions above present assumptions and constitutes 4 to 10% of total US oil and gas methane emissions, highlighting a previously underappreciated methane source and mitigation opportunity.