D-fining DarR: a LysR-type transcriptional regulator that responds to D-aspartate.

Work from Jones, Stabb, et al. describes a D-aspartate sensing system in Proteobacteria. D-amino acids are critical components of peptidoglycan and other structures. The new study identifies the LysR-type transcriptional regulator, DarR, which activates the aspartate racemase RacD. Overexpression of RacD enables it to synthesize D-glutamate and restore normal peptidoglycan in a Vibrio fischeri murI mutant. This study contributes to emerging roles for D-amino acids and how they are synthesized under distinct conditions.