Browsing by Author "Lu, J"

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    Arginine catabolism is essential to polymyxin dependence in Acinetobacter baumannii
    (Elsevier, 2024-07) Han, ML; Alsaadi, Y; Zhao, JX; Zhu, Y; Lu, J; Jiang, X; Ma, W; Patil, NA; Dunstan, RA; Le Brun, AP; Wickremasinghe, H; Hu, X; Wu, Y; Yu, HH; Wang, J; Barlow, CK; Bergen, PJ; Shen, HH; Lithgow, T; Creek, DJ; Velkov, T; Li, J
    Polymyxins are often the only effective antibiotics against the "Critical" pathogen Acinetobacter baumannii. Worryingly, highly polymyxin-resistant A. baumannii displaying dependence on polymyxins has emerged in the clinic, leading to diagnosis and treatment failures. Here, we report that arginine metabolism is essential for polymyxin-dependent A. baumannii. Specifically, the arginine degradation pathway was significantly altered in polymyxin-dependent strains compared to wild-type strains, with critical metabolites (e.g., L-arginine and L-glutamate) severely depleted and expression of the astABCDE operon significantly increased. Supplementation of arginine increased bacterial metabolic activity and suppressed polymyxin dependence. Deletion of astA, the first gene in the arginine degradation pathway, decreased phosphatidylglycerol and increased phosphatidylethanolamine levels in the outer membrane, thereby reducing the interaction with polymyxins. This study elucidates the molecular mechanism by which arginine metabolism impacts polymyxin dependence in A. baumannii, underscoring its critical role in improving diagnosis and treatment of life-threatening infections caused by "undetectable" polymyxin-dependent A. baumannii. ª 2024 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY-NC licence
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    Magnetic structure and properties of the Na2CoP2O7 pyrophosphate cathode for sodium-ion batteries: a supersuperexchange-driven non-collinear antiferromagnet
    (American Chemical Society, 2012-12-17) Barpanda, P; Avdeev, M; Ling, CD; Lu, J; Yamada, A
    The crystal and magnetic structure and properties of the Na2CoP2O7 Na+-ion battery cathode material have been characterized by magnetic susceptibility, specific heat, and variable-temperature neutron powder diffraction measurements. Na2CoP2O7 crystallizes in the orthorhombic space group Pna21 with a = 15.4061(3) Å, b = 10.28854(9) Å, and c = 7.70316(15) Å, having a layered structure with slabs of [CoP2O7]∞ separated by Na cations. The magnetic property measurements and neutron diffraction data analysis reveal that the material undergoes long-range ordering to a noncollinear antiferromagnetic G-type structure below TN ≈ 6.5 K. The magnetic structure is rationalized as a result of supersuperexchange between Co2+ atoms linked by phosphate groups.© 2013, American Chemical Society.
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    Magnetic structures of NaFePO4 maricite and triphylite polymorphs for sodium-ion batteries
    (American Chemical Society, 2013-08-05) Avdeev, M; Mohamed, Z; Ling, CD; Lu, J; Tamaru, M; Yamada, A; Barpanda, P
    The magnetic structure and properties of polycrystalline NaFePO4 polymorphs, maricite and triphylite, both derived from the olivine structure type, have been investigated using magnetic susceptibility, heat capacity, and low-temperature neutron powder diffraction. These NaFePO4 polymorphs assume orthorhombic frameworks (space group No. 62, Pnma), built from FeO6 octahedral and PO4 tetrahedral units having corner-sharing and edge-sharing arrangements. Both polymorphs demonstrate antiferromagnetic ordering below 13 K for maricite and 50 K for triphylite. The magnetic structure and properties are discussed considering super- and supersuperexchange interactions in comparison to those of triphylite-LiFePO4. © 2013, American Chemical Society
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    On the structure of α-BiFeO3
    (American Chemical Society, 2013-03-04) Wang, H; Yang, CX; Lu, J; Wu, MM; Su, J; Li, K; Zhang, JR; Li, GB; Jin, T; Kamiyama, T; Liao, FH; Lin, JH; Wu, YC
    Polycrystalline and monocrystalline α-BiFeO3 crystals have been synthesized by solid state reaction and flux growth method, respectively. X-ray, neutron, and electron diffraction techniques are used to study the crystallographic and magnetic structure of α-BiFeO3. The present data show that α-BiFeO3 crystallizes in space group P1 with a = 0.563?17(1) nm, b = 0.563?84(1) nm, c = 0.563?70(1) nm, α = 59.33(1)°, ? = 59.35(1)°, ? = 59.38(1)°, and the magnetic structure of α-BiFeO3 can be described by space group P1 with magnetic modulation vector in reciprocal space q = 0.0045a* ? 0.0045b*, which is the magnetic structure model proposed by I. Sosnowska(1) applied to the new P1 crystal symmetry of α-BiFeO3. © 2013 American Chemical Society
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    Reconstitution of a nanomachine driving the assembly of proteins into bacterial outer membranes
    (Macmillan Publishers Limited., 2014-10-24) Shen, HH; Leyton, DL; Shiota, T; Belousoff, MJ; Noinaj, N; Lu, J; Holt, SA; Tan, K; Selkrig, J; Webb, CT; Buchanan, SK; Martin, LL; Lithgow, T
    In biological membranes, various protein secretion devices function as nanomachines, and measuring the internal movements of their component parts is a major technological challenge. The translocation and assembly module (TAM) is a nanomachine required for virulence of bacterial pathogens. We have reconstituted a membrane containing the TAM onto a gold surface for characterization by quartz crystal microbalance with dissipation (QCM-D) and magnetic contrast neutron reflectrometry (MCNR). The MCNR studies provided structural resolution down to 1 Å, enabling accurate measurement of protein domains projecting from the membrane layer. Here we show that dynamic movements within the TamA component of the TAM are initiated in the presence of a substrate protein, Ag43, and that these movements recapitulate an initial stage in membrane protein assembly. The reconstituted system provides a powerful new means to study molecular movements in biological membranes, and the technology is widely applicable to studying the dynamics of diverse cellular nanomachines. © Macmillan Publishers Limited
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    Unravelling the nature of the intrinsic complex structure of binary‐phase Na‐layered oxides
    (Wiley, 2022-07) Paidi, AK; Park, WB; Ramakrishnan, P; Lee, SH; Lee, JW; Lee, KS; Ahn, H; Liu, T; Gim, J; Avdeev, M; Pyo, M; Sohn, JI; Amine, K; Sohn, KS; Shin, TJ; Ahn, D; Lu, J
    The layered sodium transition metal oxide, NaTMO2 (TM = transition metal), with a binary or ternary phases has displayed outstanding electrochemical performance as a new class of strategy cathode materials for sodium‐ion batteries (SIBs). Herein, an in‐depth phase analysis of developed Na1−xTMO2 cathode materials, Na0.76Ni0.20Fe0.40Mn0.40O2 with P2‐ and O3‐type phases (NFMO‐P2/O3) is offered. Structural visualization on an atomic scale is also provided and the following findings are unveiled: i) the existence of a mixed‐phase intergrowth layer distribution and unequal distribution of P2 and O3 phases along two different crystal plane indices and ii) a complete reversible charge/discharge process for the initial two cycles that displays a simple phase transformation, which is unprecedented. Moreover, first‐principles calculations support the evidence of the formation of a binary NFMO‐P2/O3 compound, over the proposed hypothetical monophasic structures (O3, P3, O′3, and P2 phases). As a result, the synergetic effect of the simultaneous existence of P‐ and O‐type phases with their unique structures allows an extraordinary level of capacity retention in a wide range of voltage (1.5–4.5 V). It is believed that the insightful understanding of the proposed materials can introduce new perspectives for the development of high‐voltage cathode materials for SIBs. © 1999-2024 John Wiley & Sons