Functional characterization of a new effector-protein family (DELD) from Piriformospora indica induced during the biotrophic colonization of host roots
Zusammenfassung der Projektergebnisse
In conclusion we have shown that P. indica Dld1 is a novel metal ion-binding histidine zipper, which is part of a large paralogous family of proteins. In cooperation with the group of Prof. Lupas the crystal structure of Dld1 was solved. Although proteins with clear homology to Dld1 have not been identified in other fungal genomes and no related proteins could be found by Dali searches with the Dld1 crystal structure, other histidine-rich proteins and peptides with pH-dependent metal ion-binding activity have been described. These proteins and peptides often contain a large proportion of residues with small sidechains, such as glycine (Helicobacter Hpn, snake venom peptides), alanine (Dld1, Plasmodium histidine-rich protein 2, Nitrosomonas SmbP), serine (ectodomain of copper uptake protein 1), or valine (mussel foot protein 4), and, as a general property, are either intrinsically disordered or show – like Dld1 – a pH-dependent transition between ordered and disordered states. While some have been characterized to primarily coordinate one metal ion species, many show – again like Dld1 – the ability to coordinate different transition metals, with multiple binding sites of varying affinity. Although the mode of action of Dld1 remains speculative, its metalbinding properties, the inhibition of Prussian blue staining in vitro and in planta, and the inhibition of the oxidation and polymerization steps in metal ion-mediated DAB oxidation are reminiscent of a radical-scavenger protein. The increased resistance to H2O2 and iron stress upon expression of Dld1 additionally leads to the proposition that Dld1 has a role in metal ion management in the fungus and during root colonization, where an excess of iron is observed at the cell wall appositions. Taken together with our biophysical characterization indicating an optimization for iron binding, our data support a function of this histidine-rich protein as a novel metal iron chelator with a putative role in ROS scavenging and perturbation of plant immunity.
Projektbezogene Publikationen (Auswahl)
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2013. Exogenous auxin affects the oxidative burst in barley roots colonized by Piriformospora indica. Plant Signal Behav 8(4): e23572
Hilbert M, Nostadt R, Zuccaro A
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2013. Host-related metabolic cues affect colonization strategies of a root endophyte. Proceedings of the National Academy of Sciences of the United States of America 110(34): 13965-13970
Lahrmann U, Ding Y, Banhara A, Rath M, Hajirezaei MR, Doehlemann S, von Wiren N, Parniske M, Zuccaro A
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2015. Mutualistic root endophytism is not associated with the reduction of saprotrophic traits and requires a noncompromised plant innate immunity. New Phytologist 207(3): 841-857
Lahrmann U, Strehmel N, Langen G, Frerigmann H, Leson L, Ding Y, Scheel D, Herklotz S, Hilbert M, Zuccaro A
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2016. The fungal-specific ß-glucan binding lectin FGB1 alters cell wall composition and prevents glucan-triggered immunity in plants. Nat Commun.
Wawra S, Fesel P, Widmer H, Leson L, Nostadt R, Langen G, Zuccaro A
