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Publikationen - Molekulare Signalverarbeitung

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Publikation

Jindaprasert, A.; Springob, K.; Schmidt, J.; De-Eknamkul, W.; Kutchan, T.M. Pyrone polyketides synthesized by a type III polyketide synthase from Drosophyllum lusitanicum Phytochemistry 69, 3043-3053, (2008) DOI: 10.1016/j.phytochem.2008.03.013

To isolate cDNAs involved in the biosynthesis of acetate-derived naphthoquinones in Drosophyllum lusitanicum, an expressed sequence tag analysis was performed. RNA from callus cultures was used to create a cDNA library from which 2004 expressed sequence tags were generated. One cDNA with similarity to known type III polyketide synthases was isolated as full-length sequence and termed DluHKS. The translated polypeptide sequence of DluHKS showed 51–67% identity with other plant type III PKSs. Recombinant DluHKS expressed in Escherichia coli accepted acetyl-coenzyme A (CoA) as starter and carried out sequential decarboxylative condensations with malonyl-CoA yielding α-pyrones from three to six acetate units. However, naphthalenes, the expected products, were not isolated. Since the main compound produced by DluHKS is a hexaketide α-pyrone, and the naphthoquinones in D. lusitanicum are composed of six acetate units, we propose that the enzyme provides the backbone of these secondary metabolites. An involvement of accessory proteins in this biosynthetic pathway is discussed.
Publikation

Zhang, W.; Ito, H.; Quint, M.; Huang, H.; Noël, L.D.; Gray, W.M. Genetic analysis of CAND1-CUL1 interactions in Arabidopsis supports a role for CAND1-mediated cycling of the SCFTIR1 complex Proc Natl Acad Sci 105, 8470-8475, (2008) DOI: 10.1073/pnas.0804144105

SKP1-Cullin1-F-box protein (SCF) ubiquitin-ligases regulate numerous aspects of eukaryotic growth and development. Cullin-Associated and Neddylation-Dissociated (CAND1) modulates SCF function through its interactions with the CUL1 subunit. Although biochemical studies with human CAND1 suggested that CAND1 plays a negative regulatory role by sequestering CUL1 and preventing SCF complex assembly, genetic studies in Arabidopsis have shown that cand1 mutants exhibit reduced SCF activity, demonstrating that CAND1 is required for optimal SCF function in vivo. Together, these genetic and biochemical studies have suggested a model of CAND1-mediated cycles of SCF complex assembly and disassembly. Here, using the SCFTIR1 complex of the Arabidopsis auxin response pathway, we test the SCF cycling model with Arabidopsis mutant derivatives of CAND1 and CUL1 that have opposing effects on the CAND1CUL1 interaction. We find that the disruption of the CAND1CUL1 interaction results in an increased abundance of assembled SCFTIR1 complex. In contrast, stabilization of the CAND1CUL1 interaction diminishes SCFTIR1 complex abundance. The fact that both decreased and increased CAND1CUL1 interactions result in reduced SCFTIR1 activity in vivo strongly supports the hypothesis that CAND1-mediated cycling is required for optimal SCF function.
Publikation

Stenzel, I.; Hause, B.; Proels, R.; Miersch, O.; Oka, M.; Roitsch, T.; Wasternack, C. The AOC promoter of tomato is regulated by developmental and environmental stimuli Phytochemistry 69, 1859-1869, (2008) DOI: 10.1016/j.phytochem.2008.03.007

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Publikation

Fellenberg, C.; Milkowski, C.; Hause, B.; Lange, P.; Böttcher, C.; Schmidt, J.; Vogt, T. Tapetum-specific location of a cation-dependent O-methyltransferase in Arabidopsis thaliana Plant J 56, 132-145, (2008) DOI: 10.1111/j.1365-313X.2008.03576.x

Cation- and S-adenosyl-l-methionine (AdoMet)-dependent plant natural product methyltransferases are referred to as CCoAOMTs because of their preferred substrate, caffeoyl coenzyme A (CCoA). The enzymes are encoded by a small family of genes, some of which with a proven role in lignin monomer biosynthesis. In Arabidopsis thaliana individual members of this gene family are temporally and spatially regulated. The gene At1g67990 is specifically expressed in flower buds, and is not detected in any other organ, such as roots, leaves or stems. Several lines of evidence indicate that the At1g67990 transcript is located in the flower buds, whereas the corresponding CCoAOMT-like protein, termed AtTSM1, is located exclusively in the tapetum of developing stamen. Flowers of At1g67990 RNAi-suppressed plants are characterized by a distinct flower chemotype with severely reduced levels of the N ′,N ′′-bis-(5-hydroxyferuloyl)-N ′′′-sinapoylspermidine compensated for by N1,N5,N10-tris-(5-hydroxyferuloyl)spermidine derivative, which is characterized by the lack of a single methyl group in the sinapoyl moiety. This severe change is consistent with the observed product profile of AtTSM1 for aromatic phenylpropanoids. Heterologous expression of the recombinant protein shows the highest activity towards a series of caffeic acid esters, but 5-hydroxyferuloyl spermidine conjugates are also accepted substrates. The in vitro substrate specificity and the in vivo RNAi-mediated suppression data of the corresponding gene suggest a role of this cation-dependent CCoAOMT-like protein in the stamen/pollen development of A. thaliana.
Publikation

Wasternack, C.; Feussner, I. Multifunctional enzymes in oxylipin metabolism Chembiochem. 9, 2373-2375, (2008) DOI: 10.1002/cbic.200800582

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Publikation

Schilling, S.; Wasternack, C.; Demuth, H.U. Glutaminyl cyclases from animals and plants: a case of functionally convergent protein evolution Biol. Chem 389, 983-991, (2008) DOI: 10.1515/BC.2008.111

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Publikation

Brüx, A.; Liu, T-Y.; Krebs, M.; Stierhof, Y.-D.; Lohmann, J.U.; Miersch, O.; Wasternack, C.; Schumacher, K. Reduced V-ATPase Activity in the trans-Golgi Network Causes Oxylipin-Dependent Hypocotyl Growth Inhibition in Arabidopsis The Plant Cell 20, 1088-1100, (2008) DOI: 10.1105/tpc.108.058362

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Publikation

Kienow, L.; Schneider, K.; Bartsch, M.; Stuible, H.-P.; Weng, H.; Miersch, O.; Wasternack, C.; Kombrink, E. Jasmonates meet fatty acids: functional analysis of a new acyl-coenzyme A synthetase family from Arabidopsis thaliana J. Exp. Bot. 59 (2), 403-419, (2008) DOI: 10.1093/jxb/erm325

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Publikation

Gao, X.; Stumpe, M.; Feussner, I.; Kolomiets, M. A novel plastidial lipoxygenase of maize (Zea mays) ZmLOX6 encodes for a fatty acid hydroperoxide lyase and is uniquely regulated by phytohormones and pathogen infection Planta 227, 491-503, (2008) DOI: 10.1007/s00425-007-0634-8

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Publikation

Miersch, O.; Neumerkel, J.; Dippe, M.; Stenzel, I.; Wasternack, C. Hydroxylated jasmonates are commonly occurring metabolites of jasmonic acid and contribute to a partial switch-off in jasmonate signaling New Phytologist 177, 114-127, (2008) DOI: 10.1111/j.1469-8137.2007.02252.x

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