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Oxidative stress based response of a transcriptional regulator, OhrR, from Burkholderia thailandensis (LB252)
Author(s) -
Pande Anuja,
Grove Anne
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.lb252
Subject(s) - burkholderia , biochemistry , regulator , reductase , bacteria , gene , chemistry , biology , enzyme , genetics
Bacteria face a burst of oxidative species during host invasion. As a protective mechanism, they possess several proteins involved in inorganic peroxide sensing. However, much has to be discovered about the sensor‐responder proteins involved in organic hydroperoxide (OHP) resistance, which is important since OHPs are more toxic. Burkholderia thailandensis , a soil dwelling bacterium, contains genes ohrR and ohr , that are involved in OHP detoxification, with the former encoding an organic hydroperoxide reductase regulator (OhrR), a MarR family transcriptional regulator, regulating expression of the gene encoding organic hydroperoxide reductase (Ohr). EMSAs revealed specificity of B. thailandensis OhrR for the promoter region of ohr , with half‐maximal saturation of 3.6 nM. SDS‐PAGE demonstrated formation of reversible, oligomeric species of OhrR on treatment with organic and inorganic oxidants. Conformational changes were indicated by reduced thermal stability of oxidized protein compared to its reduced form (Tm 65.3 °C). Attenuated DNA binding in the presence of oxidants further confirmed structural changes in oxidized OhrR by virtue of disulfide bond formation between redox‐active cysteines. B. thailandensis shares 80% genetic homology with its pathogenic homologues B. pseudomallei and B. mallei, making characterizing its protein machinery involved in peroxide resistance even more crucial.