coli K-12 BW25113 and its plaR deletion mutant were grown in minimal M9 medium containing 0.2% galacturonate, which is a breakdown product of pectin, the rate of cell growth was higher for the plaR mutant than for the wild-type strain. On the other hand, in minimal M9 medium containing 0.2% each of sorbitol or fructose as a sole carbon source, overexpression of PlaR interfered with the cell growth [7]. PlaR recognizes -D-galacturonate and L-ascorbate as its effectors [7]. PlaR is negatively autoregulated, and it coordinately represses transcription of the divergent yiaK-S operon, related to degradation of l-lyxose [1] Additionally, its operon is activated by insertion of IS1 into the yiaJ gene [5] Although little is known about the mechanism of regulation of the YiaJ regulator, recently it has been demonstrated to act as a repressor by binding to cis-acting elements that overlap yiaKp [1] YiaJ shows high homology to the IclR family of regulators; it is composed of two domains, an amino-terminal domain that contains a potential helix-turn-helix DNA-binding motif and a carboxy-terminal region featuring a second motif of unknown function [5] Compared to known global TFs, PlaR exhibits some interesting regulatory features. First, it has more intragenic binding peaks and fewer peaks located within putative regulatory regions. Second, it has fewer binding peaks than global TFs, such as CRP, Lrp, Fnr, and ArcA. Third, it binds to more genes with putative functions. Finally, its expression level is lower than that of the majority of global TFs [3]. The most common binding mode for YiaJ is downstream of the RNAP binding region [3]. The 21-bp-long palindromic sequence, ATnTGAAACnnnGTTCAnTT, has been identified as the recognition sequence of PlaR [7].