Quantifying changes in the bacterial thiol redox proteome during host-pathogen interaction

Abstract

Phagocyte-derived production of a complex mixture of different oxidants is a major mechanism of the host defense against microbial intruders. On the protein level, a major target of these oxidants is the thiol group of the amino acid cysteine in proteins. Oxidation of thiol groups is a widespread regulatory post-translational protein modification. It is used by bacteria to respond to and to overcome oxidative stress. Numerous redox proteomic studies have shown that protein thiols in bacteria, such as Escherichia coli react towards a number of oxidants in specific ways. However, our knowledge about protein thiols in bacteria exposed to the complex mixture of oxidants encountered in the phagolysosome is still limited. In this study, we used a quantitative redox proteomic method (OxICAT) to assess the in vivo thiol oxidation status of phagocytized E. coli . The majority (65.5%) of identified proteins harbored thiols that were significantly oxidized (> 30%) upon phagocytosis. A substantial number of these proteins are from major metabolic pathways or are involved in cell detoxification and stress response, suggesting a systemic breakdown of the bacterial cysteine proteome in phagocytized bacteria. 16 of the oxidized proteins provide E. coli with a significant growth advantage in the presence of H 2 O 2 , when compared to deletion mutants lacking these proteins, and 11 were shown to be essential under these conditions.

Exposure of Pseudomonas aeruginosa to bactericidal hypochlorous acid during neutrophil phagocytosis is compromised in cystic fibrosis

“…This result suggests that at least with PsA other oxidation products of cysteine residues must be favored over glutathionylation. In contrast to our result, Xie et al (60) recently reported substantial reversible protein thiol oxidation in E. coli phagocytosed by a neutrophil-like cell line. This reversible thiol oxidation may have involved glutathionylation because GSH levels in E. coli are much higher than PsA (27,56).…”

Identification of mtROS-sensitive processes in activated CD4+T cells

“…Subsequently, we used iodoTMT reporter ion intensities to calculate the average percentage change of oxidation for each peptide. The overall distribution of the thiol oxidation states under both conditions was found notably similar and in accordance with results from other cell types (21,67). In both the stimulated and unstimulated CD4 + T cells, 92% of the characterized cysteine residues were found predominantly reduced with an oxidation status of less than 30%, with the majority residing in the 0-10% oxidation range ( Figures 3A & 3B).…”

“…Generally, there was only moderate inter-sample deviation of the same conditions between different donors (Supplementary Figure 5). It is well known that the majority of cysteine residues in proteins exist as either significantly oxidized or significantly reduced (67). The oxidation state reflects the overall thiol redox homeostasis of the compartment, with cytosolic proteins having mostly reduced cysteine residues, and conversely, extracellular proteins typically contain structural disulfide bonds.…”

Investigation on the requirements for YbbN/CnoX displaying thiol-disulfide oxidoreductase and chaperone activities

“…HOCl production by phagocytic cells is one of the central mechanisms to protect host organisms from pathogenic bacteria, including E. coli and P. aeruginosa [32][33][34] . In turn, bacteria have to deal with this intense oxidative insult, with the involvement of Cys-based proteins [35][36][37].…”