Uptake and conversion of d-amino acids in Arabidopsis thaliana

Abstract

The D-enantiomers of proteinogenic amino acids fulfill essential functions in bacteria, fungi and animals. Just in the plant kingdom, the metabolism and role of D-amino acids (D-AAs) still remains unclear, although plants have to cope with significant amounts of these compounds from microbial decay in the rhizosphere. To fill this gap of knowledge, we tested the inhibitory effects of D-AAs on plant growth and established a method to quantitate 16 out of 19 proteinogenic amino acids and their D-enantiomers in plant tissue extracts. Therefore, the amino acids in the extracts were derivatized with Marfey's reagent and separated by HPLC-MS. We used two ecotypes (Col-0 and C24) and a mutant (lht1) of the model plant Arabidopsis thaliana to determine the influence and fate of exogenously applied D-AAs. All of them were found in high concentrations in the plant extracts after application, even in lht1, which points to additional transporters facilitating the import of D-AAs. The addition of particular amino acids (D-Trp, D-Phe, D-Met and D-His) led to the accumulation of the corresponding L-amino acid. In almost all cases, the application of a D-AA resulted in the accumulation of D-Ala and D-Glu. The presented results indicate that soil borne D-AAs can actively be taken up and metabolized via central metabolic routes.

Use of Marfey's reagent and analogs for chiral amino acid analysis: Assessment and applications to natural products and biological systems

“…In their report on the investigation, uptake and conversion of d-AAs in the genome sequenced higher plant Arabidopsis thaliana (mouseear cress), Gördes et al [48] showed an overlaid chromatogram composed of 16 pairs of dl-AAs including internal standard (R)-Phg derivatized with FDNP-l-Val-NH 2 . Co-elution of several derivatives was observed.…”

“…The inhibitory effects and metabolization of d-AAs on growth of the plant A. thaliana grown in sterile nutrition broth was determined using derivatization of free d-and l-AAs with FDNP-lVal-NH 2 and LC-MS of the derivatives [48]. Authors reported that the application of d-AAs resulted in the accumulation of d-Ala and d-Glu in the plant and it was concluded that soil borne d-AAs could actively be taken up and metabolized via central metabolic routes.…”

Molecular Biology, Biochemistry and Cellular Physiology of Cysteine Metabolism inArabidopsis thaliana

“…Next, D-Cys desulfhydrases (EC 4.4.1.15) with high specificity for this enantionmer have been identified (Riemenschneider et al, 2005;Papenbrock et al, 2007). This reaction would be important in combination with a cysteine amino-acid racemase which still needs to be demonstrated (Gördes et al, 2010), leaving the role of D-cysteine unclear (Papenbrock et al, 2010). However, both desulfhydrase reactions result in the release of sulfide.…”

Widespread Inter- and Intra-Domain Horizontal Gene Transfer of d-Amino Acid Metabolism Enzymes in Eukaryotes

“…Catabolism of d -amino acid may be important in environments where other nitrogen sources are scarce. d -amino acids are considerably toxic for many organisms, including many bacteria, yeasts and plants (Yow et al, 2006; Chen et al, 2010; Gördes et al, 2011, 2013; Zhang and Sun, 2014; Leiman et al, 2015), and thus the ecological interactions between fungi, plants and environmental d -amino acids is worth examining. At least two pathogenic yeast species, Candida glabrata and Candida orthopsilosis harbor their own horizontally acquired amino acid racemases (Fitzpatrick et al, 2008; Marcet-Houben and Gabaldón, 2010), an aspartate-glutamate-hydantoin racemase and a proline racemase, respectively.…”