Regulator SlyA Controls Bacterial Acid Resistance by Directly Activating the Glutamate Decarboxylation System.

is an important foodborne bacterial pathogen with infectious dose as low as 10-100 cells. SlyA, a transcriptional regulator of the MarR family, has been shown to regulate virulence in a closely related bacterial pathogen, Typhimurium. However, the regulatory role of SlyA in is less understood. Here we applied unbiased proteomic profiling to define the SlyA regulon in . We found that the genetic ablation of led to the alteration of 18 bacterial proteins among over 1400 identifications. Intriguingly, most down-regulated proteins (whose expression is SlyA-dependent) were associated with bacterial acid resistance such as the glutamate decarboxylation system. We further demonstrated that SlyA directly regulates the expression of GadA, a glutamate decarboxylase, by binding to the promotor region of its coding gene. Importantly, overexpression of GadA was able to rescue the survival defect of the Δ mutant under acid stress. Therefore, our study highlights a major role of SlyA in controlling acid resistance and provides a molecular mechanism underlying such regulation as well.