The conundrum in enzymatic reactions related to biosynthesis of d-amino acids in bacteria

Abstract

d-Amino acids (d-AAs) are key components of the peptidoglycan matrix in bacterial cells. Various bacterial species are known to produce d-AAs by using different enzymes, such as highly specific and broad-spectrum racemases. Miyamoto et al. studied the biosynthesis of d-glutamate in the hyperthermophile and anaerobic Gram-negative bacterium, Thermotoga maritima, which does not possess a broad-spectrum racemase. The investigated TM0831 enzyme catalyzes both a d-amino acid aminotransferase reaction producing d-glutamate and an amino acid racemase activity aimed at generating d-aspartate and d-glutamate from the corresponding l-enantiomers. TM0831 represents an example of natural molecular evolution process favoring the enzyme versatility. Comment on: https://doi.org/10.1111/febs.16452.

Keywords: PLP-containing enzymes; d-glutamate; enzyme promiscuity; peptidoglycan.

Fig. 1

Reactions catalyzed by TM0831 from Thermotoga  maritima. (A, D) Racemization reactions of selected amino acids; (B, C) transaminase reactions using a d‐AA as amino donor.