Geschmack ist vorhersagbar: Mit FlavorMiner. FlavorMiner heißt das Tool, das IPB-Chemiker und Partner aus Kolumbien jüngst entwickelt haben. Das Programm kann, basierend auf maschinellem Lernen (KI), anhand der…
Seit Februar 2021 bietet Wolfgang Brandt, ehemaliger Leiter der Arbeitsgruppe Computerchemie am IPB, sein Citizen Science-Projekt zur Pilzbestimmung an. Dafür hat er in regelmäßigen Abständen öffentliche Vorträge zur Vielfalt…
Prasad, A.; Breithaupt, C.; Nguyen, D.-A.; Lilie, H.; Ziegler, J.; Stubbs, M. T.;Mechanism of chorismate dehydratase MqnA, the first enzyme of the futalosine pathway, proceeds via substrate-assisted catalysisJ. Biol. Chem.298102601(2022)DOI: 10.1016/j.jbc.2022.102601
MqnA, the only chorismate dehydratase known so far, catalyzes the initial step in the biosynthesis of menaquinone via the futalosine pathway. Details of the MqnA reaction mechanism remain unclear. Here, we present crystal structures of Streptomyces coelicolor MqnA and its active site mutants in complex with chorismate and the product 3-enolpyruvyl-benzoate, produced during heterologous expression in Escherichia coli. Together with activity studies, our data are in line with dehydration proceeding via substrate assisted catalysis, with the enol pyruvyl group of chorismate acting as catalytic base. Surprisingly, structures of the mutant Asn17Asp with copurified ligand suggest that the enzyme converts to a hydrolase by serendipitous positioning of the carboxyl group. All complex structures presented here exhibit a closed Venus flytrap fold, with the enzyme exploiting the characteristic ligand binding properties of the fold for specific substrate binding and catalysis. The conformational rearrangements that facilitate complete burial of substrate/product, with accompanying topological changes to the enzyme surface, could foster substrate channeling within the biosynthetic pathway.
Publikation
Ricardo, M. G.; Moya, C. G.; Pérez, C. S.; Porzel, A.; Wessjohann, L. A.; Rivera, D. G.;Improved Stability and Tunable Functionalization of Parallel β‐Sheets via Multicomponent N‐Alkylation of the Turn MoietyAngew. Chem.132265-269(2020)DOI: 10.1002/ange.201912095
In contrast to the myriad of methods available to produce α‐helices and antiparallel β‐sheets in synthetic peptides, just a few are known for the construction of stable, non‐cyclic parallel β‐sheets. Herein, we report an efficient on‐resin approach for the assembly of parallel β‐sheet peptides in which the N‐alkylated turn moiety enhances the stability and gives access to a variety of functionalizations without modifying the parallel strands. The key synthetic step of this strategy is the multicomponent construction of an N‐alkylated turn using the Ugi reaction on varied isocyano‐resins. This four‐component process assembles the orthogonally protected turn fragment and incorporates handles serving for labeling/conjugation purposes or for reducing peptide aggregation. NMR and circular dichroism analyses confirm the better‐structured and more stable parallel β‐sheets in the N‐alkylated peptides compared to the non‐functionalized variants.
Publikation
Matern, A.; Böttcher, C.; Eschen-Lippold, L.; Westermann, B.; Smolka, U.; Döll, S.; Trempel, F.; Aryal, B.; Scheel, D.; Geisler, M.; Rosahl, S.;A substrate of the ABC transporter PEN3 stimulates bacterial flagellin (flg22)-induced callose deposition in Arabidopsis thalianaJ. Biol. Chem.2946857-6870(2019)DOI: 10.1074/jbc.RA119.007676
Nonhost resistance of Arabidopsis thaliana against Phytophthora infestans, a filamentous eukaryotic microbe and the causal agent of potato late blight, is based on a multilayered defense system. Arabidopsis thaliana controls pathogen entry through the penetration-resistance genes PEN2 and PEN3, encoding an atypical myrosinase and an ABC transporter, respectively, required for synthesis and export of unknown indole compounds. To identify pathogen-elicited leaf surface metabolites and further unravel nonhost resistance in Arabidopsis, we performed untargeted metabolite profiling by incubating a P. infestans zoospore suspension on leaves of WT or pen3 mutant Arabidopsis plants. Among the plant-secreted metabolites, 4-methoxyindol-3-yl-methanol and S-(4-methoxy-indol-3-yl-methyl) cysteine were detected in spore suspensions recollected from WT plants, but at reduced levels from the pen3 mutant plants. In both whole-cell and microsome-based assays, 4-methoxyindol-3-yl-methanol was transported in a PEN3-dependent manner, suggesting that this compound is a PEN3 substrate. The syntheses of both compounds were dependent on functional PEN2 and phytochelatin synthase 1. None of these compounds inhibited mycelial growth of P. infestans in vitro. Of note, exogenous application of 4-methoxyindol-3-yl methanol slightly elevated cytosolic Ca2+ levels and enhanced callose deposition in hydathodes of seedlings treated with a bacterial pathogen-associated molecular pattern (PAMP), flagellin (flg22). Loss of flg22-induced callose deposition in leaves of pen3 seedlings was partially reverted by the addition of 4-methoxyindol-3-yl methanol. In conclusion, we have identified a specific indole compound that is a substrate for PEN3 and contributes to the plant defense response against microbial pathogens.
Publikation
Hock, K. J.; Knorrscheidt, A.; Hommelsheim, R.; Ho, J.; Weissenborn, M. J.; Koenigs, R. M.;Eisenporphyrin-katalysierte C-H-Funktionalisierung von Indol mit Diazoacetonitril für die Synthese von TryptaminenAngew. Chem.1313669-3673(2019)DOI: 10.1002/ange.201813631
Die Funktionalisierung von C‐H‐Bindungen mit Nichtedelmetallkatalysatoren ist ein wichtiges Forschungsgebiet für die Entwicklung effizienter und nachhaltiger Synthesemethoden. In diesem Artikel beschreiben wir die Entwicklung Eisenporphyrin‐katalysierter Reaktionen von Diazoacetonitril mit N‐Heterocyclen um so einen Zugang zu wertvollen Vorläufern zu Tryptaminen zu erhalten. Darüberhinaus berichten wir über experimentelle mechanistische Studien sowie über konzeptionelle Studien zu einer enzymatischen Synthese mit dem Enzym YfeX. Mit dem leicht zugänglichen FeTPPCl‐Katalysator konnten wir hoch effiziente C‐H‐Funktionalisierungsreaktionen von Indol und Indazol‐Heterocyclen zeigen. Diese Reaktionen können unter milden Reaktionsbedingungen, mit exzellenten Ausbeuten und großer Toleranz funktioneller Gruppen inklusive Anwendungen im Grammmaßstab durchgeführt werden und eröffnen so einen einzigartigen, effizienten Zugang zu Tryptaminen.