Browsing by Author "Hniopek, Julian"
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- ItemMultimodal Molecular Imaging and Identification of Bacterial Toxins Causing Mushroom Soft Rot and Cavity Disease(Weinheim : Wiley-VCH, 2021) Dose, Benjamin; Thongkongkaew, Tawatchai; Zopf, David; Kim, Hak Joong; Bratovanov, Evgeni V.; García-Altares, María; Scherlach, Kirstin; Kumpfmüller, Jana; Ross, Claudia; Hermenau, Ron; Niehs, Sarah; Silge, Anja; Hniopek, Julian; Schmitt, Michael; Popp, Jürgen; Hertweck, ChristianSoft rot disease of edible mushrooms leads to rapid degeneration of fungal tissue and thus severely affects farming productivity worldwide. The bacterial mushroom pathogen Burkholderia gladioli pv. agaricicola has been identified as the cause. Yet, little is known about the molecular basis of the infection, the spatial distribution and the biological role of antifungal agents and toxins involved in this infectious disease. We combine genome mining, metabolic profiling, MALDI-Imaging and UV Raman spectroscopy, to detect, identify and visualize a complex of chemical mediators and toxins produced by the pathogen during the infection process, including toxoflavin, caryoynencin, and sinapigladioside. Furthermore, targeted gene knockouts and in vitro assays link antifungal agents to prevalent symptoms of soft rot, mushroom browning, and impaired mycelium growth. Comparisons of related pathogenic, mutualistic and environmental Burkholderia spp. indicate that the arsenal of antifungal agents may have paved the way for ancestral bacteria to colonize niches where frequent, antagonistic interactions with fungi occur. Our findings not only demonstrate the power of label-free, in vivo detection of polyyne virulence factors by Raman imaging, but may also inspire new approaches to disease control. © 2021 The Authors. ChemBioChem published by Wiley-VCH GmbH
- ItemNovel Biobased Self-Healing Ionomers Derived from Itaconic Acid Derivates(Weinheim : Wiley-VCH, 2021) Meurer, Josefine; Hniopek, Julian; Dahlke, Jan; Schmitt, Michael; Popp, Jürgen; Zechel, Stefan; Hager, Martin D.This article presents novel biobased ionomers featuring self-healing abilities. These smart materials are synthesized from itaconic acid derivates. Large quantities of itaconic acid can be produced from diverse biomass like corn, rice, and others. This study presents a comprehensive investigation of their thermal and mechanical properties via differential scanning calorimetry (DSC), thermo gravimetric analysis (TGA), and FT-Raman and FT-IR measurements as well as dynamic mechanic analysis. Within all these measurements, different kinds of structure-property relationships could be derived from these measurements. For example, the proportion of ionic groups enormously influences the self-healing efficiency. The investigation of the self-healing abilities reveals healing efficiencies up to 99% in 2 h at 90 °C for the itaconic acid based ionomer with the lowest ionic content. © 2020 The Authors. Macromolecular Rapid Communications published by Wiley-VCH GmbH
- ItemPhotophysics of Anionic Bis(4H-imidazolato)CuI Complexes(Weinheim : Wiley-VCH, 2022) Seidler, Bianca; Tran, Jens H.; Hniopek, Julian; Traber, Philipp; Görls, Helmar; Gräfe, Stefanie; Schmitt, Michael; Popp, Jürgen; Schulz, Martin; Dietzek‐Ivanšić, BenjaminIn this paper, the photophysical behavior of four panchromatically absorbing, homoleptic bis(4H-imidazolato)CuI complexes, with a systematic variation in the electron-withdrawing properties of the imidazolate ligand, were studied by wavelength-dependent time-resolved femtosecond transient absorption spectroscopy. Excitation at 400, 480, and 630 nm populates metal-to-ligand charge transfer, intraligand charge transfer, and mixed-character singlet states. The pump wavelength-dependent transient absorption data were analyzed by a recently established 2D correlation approach. Data analysis revealed that all excitation conditions yield similar excited-state dynamics. Key to the excited-state relaxation is fast, sub-picosecond pseudo-Jahn-Teller distortion, which is accompanied by the relocalization of electron density onto a single ligand from the initially delocalized state at Franck-Condon geometry. Subsequent intersystem crossing to the triplet manifold is followed by a sub-100 ps decay to the ground state. The fast, nonradiative decay is rationalized by the low triplet-state energy as found by DFT calculations, which suggest perspective treatment at the strong coupling limit of the energy gap law.
- ItemA polyyne toxin produced by an antagonistic bacterium blinds and lyses a Chlamydomonad alga(Washington, DC : National Acad. of Sciences, 2021) Hotter, Vivien; Zopf, David; Kim, Hak Joong; Silge, Anja; Schmitt, Michael; Aiyar, Prasad; Fleck, Johanna; Matthäus, Christian; Hniopek, Julian; Yan, Qing; Loper, Joyce; Sasso, Severin; Hertweck, Christian; Popp, Jürgen; Mittag, MariaAlgae are key contributors to global carbon fixation and form the basis of many food webs. In nature, their growth is often supported or suppressed by microorganisms. The bacterium Pseudomonas protegens Pf-5 arrests the growth of the green unicellular alga Chlamydomonas reinhardtii, deflagellates the alga by the cyclic lipopeptide orfamide A, and alters its morphology [P. Aiyar et al., Nat. Commun. 8, 1756 (2017)]. Using a combination of Raman microspectroscopy, genome mining, and mutational analysis, we discovered a polyyne toxin, protegencin, which is secreted by P. protegens, penetrates the algal cells, and causes destruction of the carotenoids of their primitive visual system, the eyespot. Together with secreted orfamide A, protegencin thus prevents the phototactic behavior of C. reinhardtii. A mutant of P. protegens deficient in protegencin production does not affect growth or eyespot carotenoids of C. reinhardtii. Protegencin acts in a direct and destructive way by lysing and killing the algal cells. The toxic effect of protegencin is also observed in an eyeless mutant and with the colony-forming Chlorophyte alga Gonium pectorale. These data reveal a two-pronged molecular strategy involving a cyclic lipopeptide and a conjugated tetrayne used by bacteria to attack select Chlamydomonad algae. In conjunction with the bloom-forming activity of several chlorophytes and the presence of the protegencin gene cluster in over 50 different Pseudomonas genomes [A. J. Mullins et al., bioRxiv [Preprint] (2021). https://www.biorxiv.org/content/10.1101/2021.03.05.433886v1 (Accessed 17 April 2021)], these data are highly relevant to ecological interactions between Chlorophyte algae and Pseudomonadales bacteria.
- ItemShape-Memory Metallopolymer Networks Based on a Triazole–Pyridine Ligand(Basel : MDPI, 2019) Meurer, Josefine; Hniopek, Julian; Zechel, Stefan; Enke, Marcel; Vitz, Jürgen; Schmitt, Michael; Popp, Jürgen; Hager, Martin D.; Schubert, Ulrich S.Shape memory polymers represent an interesting class of stimuli-responsive polymers. With their ability to memorize and recover their original shape, they could be useful in almost every area of our daily life. We herein present the synthesis of shape-memory metallopolymers in which the switching unit is designed by using bis(pyridine–triazole) metal complexes. The polymer networks were synthesized via free radical polymerization of methyl-, ethyl- or butyl-methacrylate, tri(ethylene glycol) dimethacrylate and a methacrylate moiety of the triazole–pyridine ligand. By the addition of zinc(II) or cobalt(II) acetate it was possible to achieve metallopolymer networks featuring shape-memory abilities. The successful formation of the metal-ligand complex was proven by Fourier transform infrared (FT-IR) spectroscopy and by 1H NMR spectroscopy. Furthermore, the shape-recovery behavior was studied in detailed fashion and even triple-shape memory behavior could be revealed.
- ItemShape-Memory Metallopolymers Based on Two Orthogonal Metal–Ligand Interactions(Weinheim : Wiley-VCH, 2021) Meurer, Josefine; Hniopek, Julian; Bätz, Thomas; Zechel, Stefan; Enke, Marcel; Vitz, Jürgen; Schmitt, Michael; Popp, Jürgen; Hager, Martin D.; Schubert, Ulrich S.A new shape-memory polymer is presented, in which both the stable phase as well as the switching unit consist of two different metal complexes. Suitable metal ions, which simultaneously form labile complexes with histidine and stable ones with terpyridine ligands, are identified via isothermal titration calorimetry (ITC) measurements. Different copolymers are synthesized, which contain butyl methacrylate as the main monomer and the metal-binding ligands in the side chains. Zn(TFMS)2 and NiCl2 are utilized for the dual crosslinking, resulting in the formation of metallopolymer networks. The switching temperature can simply be tuned by changing the composition as well as by the choice of the metal ion. Strain fixity rates (about 99%) and very high strain recovery rates (up to 95%) are achieved and the mechanism is revealed using different techniques such as Raman spectroscopy. © 2021 The Authors. Advanced Materials published by Wiley-VCH GmbH