Filter and export

Publications

What is a Publication?
5 Publications visible to you, out of a total of 5
Multimodal Molecular Imaging and Identification of Bacterial Toxins Causing Mushroom Soft Rot and Cavity Disease

Abstract (Expand)

Soft 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, 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.

Authors: Benjamin Dose, Tawatchai Thongkongkaew, David Zopf, Hak Joong Kim, Evgeni V. Bratovanov, María García-Altares Pérez, Kirstin Scherlach, Jana Krabbe, Claudia Ross, Ron Hermenau, Sarah P. Niehs, Anja Silge, Julian Hniopek, Michael Schmitt, Jürgen Popp, Christian Hertweck

Date Published: 7th Jul 2021

Publication Type: Journal

Iron Coordination Properties of Gramibactin as Model for the New Class of Diazeniumdiolate Based Siderophores.

Abstract (Expand)

Gramibactin (GBT) is an archetype for the new class of diazeniumdiolate siderophores, produced by Paraburkholderia graminis, a cereal-associated rhizosphere bacterium, for which a detailed solution … thermodynamic study exploring the iron coordination properties is reported. The acid-base behavior of gramibactin as well as its complexing ability toward Fe(3+) was studied over a wide range of pH values (2</=pH</=11). For the latter the ligand-competition method employing EDTA was used. Only two species are formed: [Fe(GBT)](-) (pH 2 to 9) and [Fe(GBT)(OH)2 ](3-) (pH>/=9). The formation of [Fe(GBT)](-) and its occurrence in real systems was confirmed by LC-HRESIMS analysis of the bacteria culture broth extract. The sequestering ability of gramibactin was also evaluated in terms of the parameters pFe and pL0.5 . Gramibactin exhibits a higher sequestering ability toward Fe(3+) than EDTA and of the same order of magnitude as hydroxamate-type microbial siderophores, but smaller than most of the catecholate-type siderophores and much higher than the most known phytosiderophores.

Authors: S. Gama, R. Hermenau, M. Frontauria, D. Milea, S. Sammartano, C. Hertweck, W. Plass

Date Published: 5th Feb 2021

Publication Type: Journal

Helper bacteria halt and disarm mushroom pathogens by linearizing structurally diverse cyclolipopeptides.

Abstract (Expand)

The bacterial pathogen Pseudomonas tolaasii severely damages white button mushrooms by secretion of the pore-forming toxin tolaasin, the main virulence factor of brown blotch disease. Yet, fungus-associated … helper bacteria of the genus Mycetocola (Mycetocola tolaasinivorans and Mycetocola lacteus) may protect their host by an unknown detoxification mechanism. By a combination of metabolic profiling, imaging mass spectrometry, structure elucidation, and bioassays, we found that the helper bacteria inactivate tolaasin by linearizing the lipocyclopeptide. Furthermore, we found that Mycetocola spp. impair the dissemination of the pathogen by cleavage of the lactone ring of pseudodesmin. The role of pseudodesmin as a major swarming factor was corroborated by identification and inactivation of the corresponding biosynthetic gene cluster. Activity-guided fractionation of the Mycetocola proteome, matrix-assisted laser desorption/ionization (MALDI) analyses, and heterologous enzyme production identified the lactonase responsible for toxin cleavage. We revealed an antivirulence strategy in the context of a tripartite interaction that has high ecological and agricultural relevance.

Authors: R. Hermenau, S. Kugel, A. J. Komor, C. Hertweck

Date Published: 31st Aug 2020

Publication Type: Not specified

Genomics-Driven Discovery of NO-Donating Diazeniumdiolate Siderophores in Diverse Plant-Associated Bacteria.

Abstract (Expand)

Siderophores are key players in bacteria-host interactions, with the main function to provide soluble iron for their producers. Gramibactin from rhizosphere bacteria expands siderophore function and … diversity as it delivers iron to the host plant and features an unusual diazeniumdiolate moiety for iron chelation. By mutational analysis of the grb gene cluster, we identified genes (grbD and grbE) necessary for diazeniumdiolate formation. Genome mining using a GrbD-based network revealed a broad range of orthologous gene clusters in mainly plant-associated Burkholderia/Paraburkholderia species. Two new types of diazeniumdiolate siderophores, megapolibactins and plantaribactin were fully characterized. In vitro assays and in vivo monitoring experiments revealed that the iron chelators also liberate nitric oxide (NO) in plant roots. This finding is important since NO donors are considered as biofertilizers that maintain iron homeostasis and increase overall plant fitness.

Authors: R. Hermenau, J. L. Mehl, K. Ishida, B. Dose, S. J. Pidot, T. P. Stinear, C. Hertweck

Date Published: 9th Sep 2019

Publication Type: Journal

Gramibactin is a bacterial siderophore with a diazeniumdiolate ligand system.

Abstract (Expand)

Genome mining and chemical analyses revealed that rhizosphere bacteria (Paraburkholderia graminis) produce a new type of siderophore, gramibactin, a lipodepsipeptide that efficiently binds iron with a … logbeta value of 27.6. Complexation-induced proton NMR chemical shifts show that the unusual N-nitrosohydroxylamine (diazeniumdiolate) moieties participate in metal binding. Gramibactin biosynthesis genes are conserved in numerous plant-associated bacteria associated with rice, wheat, and maize, which may utilize iron from the complex.

Authors: R. Hermenau, K. Ishida, S. Gama, B. Hoffmann, M. Pfeifer-Leeg, W. Plass, J. F. Mohr, T. Wichard, H. P. Saluz, C. Hertweck

Date Published: 1st Aug 2018

Publication Type: Journal

Powered by
 (v.1.15.2)
About | About ChemBioSys | Funding and Programmes | Credits
Copyright © 2008 - 2024 The University of Manchester and HITS gGmbH