Expression of glutathioneS-transferase and peptide methionine sulphoxide reductase inOchrobactrum anthropiis 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.

Growth Substrate- and Phase-Specific Expression of Biphenyl, Benzoate, and C 1 Metabolic Pathways in Burkholderia xenovorans LB400

“…Many of the noncatabolic proteins that were more abundant during growth on biphenyl and/or benzoate versus succinate appear to be associated with a stress response. Oxidative stress may originate from the dioxygenases' activity, which can produce reactive oxygen species (5,36). Four proteins that were more abundant during growth on the aromatic compounds have been linked to oxidative stress responses: the general stress protein GroEL (5,6,15); HslU (25), which degrades abnormal proteins; and AhpCF (4,21,31), which detoxifies peroxides; and a serine kinase (38).…”

Overlapping protective roles for glutathione transferase gene family members in chemical and oxidative stress response in Agrobacterium tumefaciens

“…The most striking effect was observed for AtuGST1 where tetracycline induced an approximately 19-fold increase in transcripts accumulation. A possible role for bacterial GSTs in the protection against the toxic effect of the antimicrobial agents has been suggested previously (Favaloro et al 2000;Veal et al 2002;Tamburro et al 2004;Alias and Clark 2007). For example, studies on the interaction of PmGSTB1-1 with a number of antimicrobial agents indicated that this enzyme was able to sequester antibiotics with avidity (Casalone et al 1998;Allocati et al 2008).…”

“…Several abiotic stresses and chemicals are known to affect the expression of GSTs at the transcriptional level (La Roche and Leisinger 1990;Cummins et al 1999;Tamburro et al 2004;Alias and Clark 2007); therefore, transcript accumulations for AtuGST genes were determined in normal culture conditions as well as in response to various xenobiotics, antimicrobial agents and other stress conditions. Gene expression analysis suggested that AtuGSTs genes are induced in a wide range of functions.…”

“…AtuGSTs transcript levels were measured in normal culture conditions as well as in response to various xenobiotics, antimicrobial agents and other stress conditions by real-time RT-qPCR analysis and normalised by the transcript levels of the reference gene polyribonucleotide nucleotidyltransferase (AtuPRNT) (Tamburro et al 2004;Kalloniati et al 2009). As illustrated in Fig.…”

Genetic and Genomic Insights into the Role of Benzoate-Catabolic Pathway Redundancy in Burkholderia xenovorans LB400

“…EPS cluster includes homologs for sigmaE-regulated algA and algD. SigmaE-regulated pyoverdin synthesis genes as described by Ravel (42); in the latter two, an increase of reactive oxygen species due to oxygenase activity was measured. The stress responses observed in the wild-type cells, except for that involving the PrkA serine kinase, seemed to be mitigated in the mutant strains.…”