Genomic adaptation to antimetabolites

In the shikimate pathway, seven enzymes catalyze the conversion of phosphoenolpyruvate and erythrose-4-phosphate to chorismate, the precursor for the biosynthesis of aromatic amino acids, folate species and quinones. The shikimate pathway therefore connects central carbon metabolism with the biosynthesis of aromatic compounds. While the aromatic amino acids phenylalanine, tryptophan and tyrosine are incorporated into proteins, and are therefore required in larger quantities, folates and quinones are needed only in minute amounts. The shikimate pathway also provides precursors for other aromatic metabolites such as iron chelators and antibiotics. Since the shikimate pathway occurs only in archaea, bacteria, Apicomplexa, algae, fungi and plants, its enzymes are attractive targets to antimetabolites and inhibitors. For instance, the phenylalanine analog β-2-thienylalanine (β2T) causes growth arrest of bacteria because it mimics the phenylalanine-dependent feedback inhibition of the prephenate dehydratase. β2T gained prominence as a component of the Guthrie test for detecting phenylketonuria in newborns. The most-prominent substance inhibiting the penultimate step of the shikimate pathway is the herbicide glyphosate (GS) that is used worldwide in agriculture to kill plants competing with crops. Using the Gram-positive soil bacterium Bacillus subtilis, we discovered the first transporter for the uptake of GS. Currently, we are using inhibitors of the shikimate pathway to study the molecular details of enzyme regulation, underground metabolism and to identify transporter for the aromatic amino acids.

 

Why are we interested in the shikimate pathway in B. subtilis?

  • Surprisingly, several enzymes of the shikimate pathway are encoded by essential genes.
  • Single amino acid exchanges in key enzymes result in "regulation reversal" phenotypes.
  • The transporters for the uptake of aromatic amino acids are still unknown.

 

Publications

Riedel R, Commichau FM, Benndorf D, Hertel R, Holzer K, Hoelzle LE, Mardoukhi MSY, Noack LE, Martienssen M (2024) Biodegradation of selected aminophosphonates by the novel bacterial isolate Ochrobactrum sp. BTU1. Microbiol Res. 280:127600.

Schwedt I, Schöne K, Eckert M, Pizzinato M, Winkler L, Knotkova B, Richts B, Hau JL, Steuber J, Mireles R, Noda-Garcia L, Fritz G, Mittelstädt C, Hertel R, Commichau FM (2023b) The low mutational flexibility of the 5-enolpyruvyl-shikimate-3-phosphate synthase in Bacillus subtilis is due to a higher demand for shikimate pathway intermediates. Environ Microbiol. 25: 3604 - 3622.

Schwedt I, Collignon M, Mittelstädt C, Giudici F, Rapp J, Meißner J, Link H, Hertel R, Commichau FM (2023a) Genomic adaptation of Burkholderia anthina to glyphosate uncovers a novel herbicide resistance mechanism. Environ Microbiol Rep. 15: 727-739.

Hertel R, Schöne K, Mittelstädt C, Meißner J, Zschoche N, Collignon M, Kohler C, Friedrich I, Schneider D, Hoppert M, Kuhn R, Schwedt I, Scholz P, Poehlein A, Martienssen M, Ischebeck T, Daniel R, Commichau FM (2022) Characterization of glyphosate-resistant Burkholderia anthina and Burkholderia cenocepacia isolates from a commercial Roundup solution. Environ Microbiol Rep 14: 70-84.

Hertel R, Gibhardt J, Martienssen M, Kuhn R, Commichau FM (2021) Molecular mechanisms underlying glyphosate resistance in bacteria. Environ Microbiol 23: 2891-2905.

Wicke D, Schulz LM, Lentes S, Scholz P, Poehlein A, Gibhardt J, Daniel R, Ischebeck T, Commichau FM (2019) Identification of the first glyphosate transporter by genomic adaptation. Environ Microbiol 21: 1287-1305.