Extracellular H2O2 (hydrogen peroxide) concentration required to activate the OxyR regulon

Value 1 μM
Organism Bacteria Escherichia coli
Reference Imlay JA. The molecular mechanisms and physiological consequences of oxidative stress: lessons from a model bacterium. Nat Rev Microbiol. 2013 Jul11(7):443-54. doi: 10.1038/nrmicro3032. p.446 right column 2nd paragraphPubMed ID23712352
Primary Source [38] Seaver, L. C. & Imlay, J. A. Hydrogen peroxide fluxes and compartmentalization inside growing Escherichia coli. J. Bacteriol. 183, 7182–7189 (2001). DOI: 10.1128/JB.183.24.7182-7189.2001PubMed ID11717277
Method Primary source abstract: "The rates of H(2)O(2) degradation by the two major scavenging enzymes, alkyl hydroperoxide reductase and catalase, were quantified."
Comments P.446 right column 2nd paragraph: "This threat is sensed by OxyR, a transcription factor containing an active-site Cys residue that reacts rapidly with H2O2 (Refs 39, 40) (Fig. 2a).OxyR is normally inactive during routine aerobiosis, when the intracellular H2O2 concentration is ~50 nM. However, an intracellular concentration of ~200 nM is sufficient to drive OxyR into a disulphide-bonded form that actively promotes the transcription of a dozen operons around the chromosome. Because basal Ahp activity can establish a fivefold outside-to-inside gradient, an extracellular H2O2 concentration of 1 μM is required to activate the regulon [primary source]."
Entered by Uri M
ID 112949