Proteomic changes in response to chromium(VI) toxicity in Pseudomonas aeruginosa.

A proteomic approach was used to identify proteins involved in Cr(VI) stress response of Pseudomonas aeruginosa to toxic Cr(VI). Cytosolic and membrane fractions from bacteria exposed to 300 mg l(-1) Cr(VI) were prepared, 2D gel electrophoresis in combination with MALDI-TOF MS and LC-MS/MS was used to identify proteins whose expression level increased or decreased upon exposure to Cr(VI). Overexpressed proteins include stress proteins, proteins involved in protein biosynthesis, proteins responsible for energy production, proteins involved in free radicals detoxification by the glutathione system, outer membrane proteins, MucD, while downregulated proteins were isocitrate dehydrogenase and 30S ribosomal protein S1. Under Cr(VI) exposure, upregulation of MucD (role in exopolysaccharide production) and outer membrane proteins concluded that bacteria have access to more than one resistance mechanism against toxic metal ions. We propose that the mechanisms of Cr(VI) resistance include production of exopolysaccharide and complexing of metal ions outside the cell.