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Publications - Stress and Develop Biology

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Publications

Trempel, F.; Eschen‐Lippold, L.; Bauer, N.; Ranf, S.; Westphal, L.; Scheel, D.; Lee, J.; A mutation in Asparagine‐Linked Glycosylation 12 (ALG12) leads to receptor misglycosylation and attenuated responses to multiple microbial elicitors FEBS Lett. 594, 2440-2451, (2020) DOI: 10.1002/1873-3468.13850

Changes in cellular calcium levels are one of the earliest signalling events in plants exposed to pathogens or other exogenous factors. In a genetic screen, we identified an Arabidopsis thaliana ‘changed calcium elevation 1 ’ (cce1 ) mutant with attenuated calcium response to the bacterial flagellin flg22 peptide and several other elicitors. Whole genome re‐sequencing revealed a mutation in ALG12 (Asparagine‐Linked Glycosylation 12 ) that encodes the mannosyltransferase responsible for adding the eighth mannose residue in an α‐1,6 linkage to the dolichol‐PP‐oligosaccharide N ‐glycosylation glycan tree precursors. While properly targeted to the plasma membrane, misglycosylation of several receptors in the cce1 background suggests that N ‐glycosylation is required for proper functioning of client proteins.
Publications

Trampczynska, A.; Böttcher, C.; Clemens, S.; The transition metal chelator nicotianamine is synthesized by filamentous fungi FEBS Lett. 580, 3173-3178, (2006) DOI: 10.1016/j.febslet.2006.04.073

Nicotianamine is an important metal ligand in plants. Surprisingly, recent genome sequencing revealed that ascomycetes encode proteins with similarity to plant nicotianamine synthases (NAS). By expression in a Zn2+‐hypersensitive fission yeast mutant we show for a protein from Neurospora crassa that it indeed possesses NAS activity. Using electrospray‐ionization‐quadrupole‐time‐of‐flight mass spectrometry we prove the formation of nicotianamine in N. crassa . Transcript level is strongly upregulated under Zn deficiency as shown by real‐time PCR. These findings demonstrate that nicotianamine is more widespread in nature than anticipated and provide further evidence for a function of nicotianamine as a cytosolic chelator of Zn2+ ions.
Publications

Grzam, A.; Tennstedt, P.; Clemens, S.; Hell, R.; Meyer, A. J.; Vacuolar sequestration of glutathione S-conjugates outcompetes a possible degradation of the glutathione moiety by phytochelatin synthase FEBS Lett. 580, 6384-6390, (2006) DOI: 10.1016/j.febslet.2006.10.050

Monochlorobimane was used as a model xenobiotic for Arabidopsis to directly monitor the compartmentation of glutathione‐bimane conjugates in situ and to quantify degradation intermediates in vitro. Vacuolar sequestration of the conjugate was very fast and outcompeted carboxypeptidation to the γ‐glutamylcysteine‐bimane intermediate (γ‐EC‐B) by phytochelatin synthase (PCS) in the cytosol. Following vacuolar sequestration, degradation proceeded to cysteine‐bimane without intermediate. Only co‐infiltration of monochlorobimane with Cd2+ and Cu2+ increased γ‐EC‐B formation to 4% and 25%, respectively, within 60 min. The role of PCS under simultaneous heavy metal stress was confirmed by investigation of different pcs1 null‐mutants. In the absence of elevated heavy metal concentrations glutathione‐conjugates are therefore first sequestered to the vacuole and subsequently degraded with the initial breakdown step being rate‐limiting.
Books and chapters

Clemens, S.; Simm, C.; Maier, T.; Heavy Metal‐binding Proteins and Peptides (2005) DOI: 10.1002/3527600035.bpol8010

IntroductionHistorical OutlineChemical StructuresNomenclature and Structure of MetallothioneinsPhytochelatins and Phytochelatin–Metal ComplexesStructural Properties of MetallochaperonesChemical Analysis and DetectionMetallothioneinsPhytochelatinsOccurrenceMetallothioneinsPhytochelatinsMetallochaperonesFunctionsMetal Homeostasis and the Role of MetallochaperonesBuffering and DetoxificationPhytochelatin FunctionsMetallothionein FunctionsPhysiologyMetallothionein Localization and IsoformsLocalization and Compartmentation of Phytochelatin SynthesisBiochemistryMetal‐binding Characteristics of MetallothioneinsBiochemistry of Phytochelatin SynthesisMolecular GeneticsMetallothionein Genes and Their RegulationPhytochelatin Synthase GenesBiotechnological ApplicationsPatentsOutlook and Perspectives
Books and chapters

Scheel, D.; Nuernberger, T.; Signal Transduction in Plant Defense Responses to Fungal Infection 1-30, (2004)

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Books and chapters

Rosahl, S.; Feussner, I.; Oxylipins 329-354, (2004)

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Books and chapters

Lee, J.; Nürnberger, T.; Is Pore Formation Activity of HrpZ Required for Defence Activation in Plant Cells? 165-173, (2003) DOI: 10.1007/978-94-017-0133-4_18

The HrpZ gene product, harpin, is an export substrate of the type III secretion system of phytopathogenic Pseudomonas syringae. The role of this protein in pathogenesis is largely unknown. We previously determined that HrpZ binds to lipids and can form cation pores in synthetic lipid bilayers. Such pore-forming activity may allow nutrient release during bacterial colonisation of host plants. In addition. HrpZ is known to trigger plant defence responses in a variety of plants, such as tobacco. We have previously also characterised a binding site in tobacco plasma membranes that likely mediates HrpZ-induced defence responses. In order to reconcile these findings, we pose the question as to whether the activation of plant defence responses by HrpZ is mediated through a “classical” receptor perception mode or if plant membrane perturbation through the inherent pore-forming activity of HrpZ may induce defence responses. As defence in parsley cells can be induced both in a receptor-mediated manner or through ionophores these cells served as an ideal system for our analysis. We first performed ligand binding studies to characterise the presence of a binding site/receptor. We further digested HrpZ with endopeptidases and used subfragments of HrpZ to assess the elicitor-active domain of HrpZ. A C-terminal region of HrpZ appears to be sufficient to elicit plant defence responses. A novel assay involving dye-loaded liposomes was developed to validate previous electrophysiological findings on HrpZ-mediated cation pore formation. More importantly, this assay was used to establish if the elicitor-active C-terminal fragment of HrpZ could form pores. Our findings suggest that the structural requirements for ion pore formation and activation of plant defence responses by HrpZ are different. Thus, ion pore formation alone may not explain the activation of plant defence by HrpZ.
Books and chapters

Scheel, D.; Oxidative burst and the role of reactive oxygen species in plant-pathogen interactions (Inzé, D. & van Montagu, M., eds.). 137-153, (2002)

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Books and chapters

Clemens, S.; Thomine, S.; Schroeder, J. I.; Molecular mechanisms that control plant tolerance to heavy metals and possible roles towards manipulating metal accumulation 665-691, (2002)

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Publications

Stumpe, M.; Kandzia, R.; Göbel, C.; Rosahl, S.; Feussner, I.; A pathogen-inducible divinyl ether synthase (CYP74D) from elicitor-treated potato suspension cells FEBS Lett. 507, 371-376, (2001) DOI: 10.1016/S0014-5793(01)03019-8

In elicitor-treated potato cells, 9-lipoxygenase-derived oxylipins accumulate with the divinyl ether colneleic acid as the major metabolite. Here, the identification of a potato cDNA is described, whose predicted amino acid sequence corresponds to divinyl ether synthases, belonging to the recently identified new P450 subfamily CYP74D. The recombinant protein was expressed in Escherichia coli and shown to metabolize 9-hydroperoxy linoleic acid to colneleic acid at pH 6.5. This fatty acid derivative has been implicated in functioning as a plant antimicrobial compound. RNA blot analyses revealed accumulation of divinyl ether synthase transcripts both upon infiltration of potato leaves with Pseudomonas syringae and after infection with Phytophthora infestans.
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