Publications

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153 Publications visible to you, out of a total of 153

Abstract (Expand)

Gliotoxin and related epidithiodiketopiperazines (ETP) from diverse fungi feature highly functionalized hydroindole scaffolds with an array of medicinally and ecologically relevant activities. Mutation analysis, heterologous reconstitution, and biotransformation experiments revealed that a cytochrome P450 monooxygenase (GliF) from the human-pathogenic fungus Aspergillus fumigatus plays a key role in the formation of the complex heterocycle. In vitro assays using a biosynthetic precursor from a blocked mutant showed that GliF is specific to ETPs and catalyzes an unprecedented heterocyclization reaction that cannot be emulated with current synthetic methods. In silico analyses indicate that this rare biotransformation takes place in related ETP biosynthetic pathways.

Authors: D. H. Scharf, P. Chankhamjon, K. Scherlach, J. Dworschak, T. Heinekamp, M. Roth, A. A. Brakhage, C. Hertweck

Date Published: 15th Jan 2021

Publication Type: Journal

Abstract (Expand)

When herbivores attack, plants specifically reconfigure their metabolism. Herbivory on the wild tobacco Nicotiana attenuata strongly induces the R2R3 MYB transcriptional activator MYB8, which was reported to specifically regulate the accumulation of phenolamides (PAs). We discovered that transcriptional regulation of trypsin protease inhibitors (TPIs) and a threonine deaminase (TD) also depend on MYB8 expression. Induced distributions of PAs, TD and TPIs all meet predictions of optimal defense theory: their leaf concentrations increase with the fitness value and the probability of attack of the tissue. Therefore, we suggest that these defensive compounds have evolved to be co-regulated by MYB8.

Authors: M. Schafer, C. Brutting, S. Xu, Z. Ling, A. Steppuhn, I. T. Baldwin, M. C. Schuman

Date Published: 27th Aug 2017

Publication Type: Not specified

Abstract (Expand)

The taxonomic positions of two novel aerobic, Gram-stain-positive Actinobacteria, designated RB20(T) and RB56(T), were determined using a polyphasic approach. Both were isolated from the fungus-farming termite Macrotermes natalensis. Results of 16S rRNA gene sequence analysis revealed that both strains are members of the genus Nocardia with the closest phylogenetic neighbours Nocardia miyunensis JCM12860(T) (98.9 %) and Nocardia nova DSM44481(T) (98.5 %) for RB20(T) and Nocardia takedensis DSM 44801(T) (98.3 %), Nocardia pseudobrasiliensis DSM 44290(T) (98.3 %) and Nocardia rayongensis JCM 19832(T) (98.2 %) for RB56(T). Digital DNA-DNA hybridization (DDH) between RB20(T) and N. miyunensis JCM12860(T) and N. nova DSM 44481(T) resulted in similarity values of 33.9 and 22.0 %, respectively. DDH between RB56(T) and N. takedensis DSM44801(T) and N. pseudobrasiliensis DSM44290(T) showed similarity values of 20.7 and 22.3 %, respectively. In addition, wet-lab DDH between RB56(T) and N. rayongensis JCM19832(T) resulted in 10.2 % (14.5 %) similarity. Both strains showed morphological and chemotaxonomic features typical for the genus Nocardia, such as the presence of meso-diaminopimelic acid (A2pm) within the cell wall, arabinose and galactose as major sugar components within whole cell-wall hydrolysates, the presence of mycolic acids and major phospholipids (diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol), and the predominant menaquinone MK-8 (H4, omega-cyclo). The main fatty acids for both strains were hexadecanoic acid (C16 : 0), 10-methyloctadecanoic acid (10-methyl C18 : 0) and cis-9-octadecenoic acid (C18 : 1 omega9c). We propose two novel species within the genus Nocardia: Nocardia macrotermitis sp. nov. with the type strain RB20(T) (=VKM Ac-2841(T)=NRRL B65541(T)) and Nocardia aurantia sp. nov. with the type strain RB56(T) (=VKM Ac-2842(T)=NRRL B65542(T)).

Authors: R. Benndorf, J. W. Schwitalla, K. Martin, Z. W. de Beer, J. Vollmers, A. K. Kaster, M. Poulsen, C. Beemelmanns

Date Published: 21st Aug 2020

Publication Type: Journal

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