FIG 1.

Reconstruction of hexuronate and aldarate utilization metabolic pathways and regulons in proteobacteria. The oxidative pathway for utilization of d-glucoronate and d-galacturonate (hexuronates) described in this work in the Burkholderiaceae, Comamonadaceae, Halomonadaceae, and Pseudomonadaceae feeds the downstream catabolic pathway for d-glucarate and meso-galactarate (aldarates). Two alternative aldarate catabolic pathways were described for E. coli (GarR-GarL) and Acinetobacter baylyi (KdgD and KgsD). The alternative hexuronate catabolic pathway known in E. coli and several other lineages of proteobacteria is shown in the gray box. Four novel TFs identified in this work as cognate regulators of the hexuronate and aldarate utilization pathway genes are shown in colored ovals, and their predicted target genes are marked by circles of corresponding colors. Numbers in circles show the number of genomes where the target gene is preceded by a candidate binding site for GguR (black), GudR (blue), UdhR (purple), and GulR (green) regulators. Known and predicted transporters for hexuronates and aldarates are shown in the pink box. New transporters and enzymes identified in this work are marked with an asterisk.