The salDE operon in Acinetobacter sp. strain ADP1 plays a critical role in the catabolism of ethyl salicylate, enabling the bacterium to utilize this aromatic ester as a carbon source. The operon is induced by the presence of ethyl salicylate through the action of the Arer protein, an aromatic-responsive transcriptional regulator. When ethyl salicylate is present in the environment, it binds to Arer, causing a conformational change that allows Arer to activate the transcription of the salDE operon. The operon encodes two key proteins: SalD, a transporter responsible for the uptake of ethyl salicylate into the cell, and SalE, an esterase that hydrolyzes ethyl salicylate into salicylate and ethanol. The salicylate produced by SalE serves as a critical inducer for the salAR operon, which encodes enzymes that further metabolize salicylate into catechol and ultimately feeding into the TCA cycle for energy production. Thus, the salDE operon acts as a crucial link between the transport and initial breakdown of ethyl salicylate and the activation of downstream metabolic pathways, enabling the bacterium to efficiently degrade and utilize this aromatic compound. The regulatory role of Arer ensures that the operon is expressed only when ethyl salicylate is available, optimizing the cell's metabolic response to environmental conditions.

Catabolism of salicylate esters (SalDE Operon activation) References