title: Expression of glutathione S-transferase and peptide methionine sulphoxide reductase in Ochrobactrum anthropi is correlated to the production of reactive oxygen species caused by aromatic substrates.
abstract: Peptide methionine sulphoxide reductase (MsrA) and glutathione S-transferases (GSTs) are considered as detoxification enzymes. In the xenobiotics-degrading bacterium Ochrobactrum anthropi the two enzymes are co-induced by toxic concentrations of aromatic substrates such as phenol and 4-chlorophenol. In aerobic organisms, degradation of aromatic substrates by mono- and dioxygenases leads to a generation of oxidative stress that causes the occurrence of reactive oxygen species (ROS). A capillary electrophoretic method, using the intracellular conversion of dihydrorhodamine-123 into rhodamine-123, was developed to measure the content of ROS in the bacteria. The presence of toxic concentrations of the aromatic substrate 4-chlorophenol, an inducer of GST and MsrA, leads to a significant increase in the production of ROS. These results strongly suggest that GST and MsrA enzymes are part of the bacterial defence mechanism against particular oxidative stress conditions. As oxidative stress is known to be present predominantly close to the cytoplasmic membrane, we investigated the subcellular distribution of both MsrA and GST enzymes in this bacterium grown in the presence of 4-chlorophenol. By Western blotting, MsrA and GST was assayed in the cytoplasm as well as in the periplasm. Moreover, immunolocalisation by colloidal gold immunoelectron microscopy identified the two proteins associated with the cell envelope.
authors.affiliation: Istituto di Ricerche Farmacologiche Mario Negri, Consorzio Mario Negri Sud, Gennaro Paone, Environmental Health Center, Via Nazionale, 66030 Santa Maria Imbaro, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Tamburro
authors.forename: Iole
authors.initials: I
authors.lastname: Robuffo
authors.forename: Hermann J
authors.initials: HJ
authors.lastname: Heipieper
authors.forename: Nerino
authors.initials: N
authors.lastname: Allocati
authors.forename: Domenico
authors.initials: D
authors.lastname: Rotilio
authors.forename: Carmine
authors.initials: C
authors.lastname: Di Ilio
authors.forename: Bartolo
authors.initials: B
authors.lastname: Favaloro
mesh_terms: D002733:Chlorophenols / Q000378:metabolism*; D003470:Culture Media; D005982:Glutathione Transferase / Q000378:metabolism*; D051150:Methionine Sulfoxide Reductases; D020621:Ochrobactrum anthropi / Q000201:enzymology* / Q000254:growth & development; D010088:Oxidoreductases / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013347:Subcellular Fractions / Q000201:enzymology
chemical_list: D002733:Chlorophenols; D003470:Culture Media; D017382:Reactive Oxygen Species; C029107:4-chlorophenol; D010088:Oxidoreductases; D051150:Methionine Sulfoxide Reductases; C027219:methionine sulfoxide reductase; D005982:Glutathione Transferase