Persönlicher Status und Werkzeuge

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Heisenberg research group Glawischnig

Tryptophan metabolism and camalexin biosynthesis

Tryptophan is a central metabolic branch point in plant metabolism, as numerous secondary metabolites, e.g. camalexin, and the plant hormone IAA are derived form this amino acid.

Camalexin biosynthesis

Camalexin, the main phytoalexin of Arabidopsis thaliana, is induced by a large array of plant pathogens. We could largely elucidate its biosynthesis, which involves multiple cytochrome P450 catalyzed steps. The first biosynthetic step is the conversion of tryptophan to indole-3-acetaldoxime (IAOx) by CYP79B2/CYP79B3. The multifunctional enzyme, CYP71B15 (PHYTOALEXIN DEFICIENT 3), converts cysteine-indole-3-acetonitrile to camalexin and cyanide.

Glawischnig et al., PNAS 2004; Schuhegger et al. Plant Phys 2006; Glawischnig, Biochem Soc Trans 2006; Nafisi et al., Plant Cell 2007; Glawischnig, Phytochemistry 2007; Rauhut et al., Phytochemistry 2009a; Böttcher et al., Plant Cell 2009, Pedras et al., Nat Prod Rep 2011, Böttcher et al., Plant Physiology 2014, Mucha et al., BMC Plant Biol 2015; Müller et al., Plant Physiology 2015

 

We currently focus on protein-protein-interactions of biosynthetic enzymes and on the evolution and metabolic engineering phytoalexin pathways.

Regulation of camalexin biosynthesis

The biosynthetic genes are highly induced upon camalexin formation in a co-ordinate and strictly localized mode. Investigation of the coordinated local camalexin response to infection with pathogens of different lifestyle, such as Alternaria or Plasmodiophora will lead to common regulators and specific features. Nep1-like proteins (NLPs) are efficient triggers of camalexin biosynthesis and inducible NLP expression in Arabidopsis was developed as a model system to study regulation of camalexin induction.

 

 

Qutob et al., Plant Cell 2006; Schuhegger et al., J Plant Phys 2007; Gust et al., JBC 2007; Siemens et al., J Phytopthology 2008; Rauhut et al., Phytochemistry 2009b; Mewis et al., PlosOne 2012, Peskan-Berghöfer et al., New Phytologist, 2015, Frerigmann et al., Front Plant Sci., 2015, Chapman et al., Phytochemistry, 2016, Frerigmann et al., Mol Plant, 2016  

Tryptophan and auxin biosynthesis in maize

Bacteria typically synthesize tryptophan by tetrameric synthase complexes of alpha and beta subunits. A similar complex, localized in plastids, was characterized in maize.

Applying retrobiosynthetic NMR analysis, we could demonstrate tryptophan-dependency of auxin biosynthesis and identified the nitrilase ZmNIT2 as biosynthetic enzyme.

Glawischnig et al., Plant Phys 2000; Glawischnig et al., Plant Phys 2001; Park et al., Plant Phys 2003; Kriechbaumer & Glawischnig JNBT, 2005; Kriechbaumer et al., Plant Biol 2006; Kriechbaumer et al., J Exp Bot 2007; Kriechbaumer et al., BMC Plant Biology 2008 Yin et al. Phytochemistry 2010