Proteomic Response to Arsenic Stress in Chromobacterium violaceum

Exposure to arsenic, whether acute or chronic, is a public health problem in many parts of the world and is associated with various types of deleterious effects on human health. One way that risk of contamination with this metalloid can be reduced is through bioremediation of areas contaminated with arsenic. Natural resistance mechanisms are widely distributed in microorganisms, meriting further study in an effort to improve their efficiency. Chromobacterium violaceum is a betaproteobacterium found in tropical and subtropical regions; its resistance to arsenic is controlled by an operon, arsRBC. The proteins expressed by the operon ars have been well studied; however, the overall cell response that determines resistance to this metalloid is little understood. We investigated changes in protein expression in response to arsenite. This was done through two-dimensional differential gel electrophoresis (2D-DIGE). Quantities of 26 proteins were altered after treatment with arsenite, 23 of which increased. The differential spots were analyzed with MS and MS/MS; eight proteins were identified that are involved in response to oxidative stress (SOD, GST, Grx), in DNA repair and in the metabolism of lipids, amino acids and coenzymes. We conclude that the response of C. violaceum to arsenite involves defense mechanisms against oxidative stress and alterations in cell metabolic cycles