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

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