Burkholderia pseudomallei RpoS regulates OxyR and the katG-dpsA operon under conditions of oxidative stress

Abstract

Burkholderia pseudomallei, the causative agent of the potentially fatal tropical disease melioidosis, is known to be highly resistant to oxidative stress although the mechanism of this resistance remains to be fully elucidated. Previous studies have shown that an OxyR is involved in the regulation of oxidative stress via the katG and dpsA genes encoding KatG and DpsA and that the alternative sigma factor, RpoS, plays a critical role in resistance to oxidative stress by regulating katG and katE genes. Here it is shown that RpoS is essential for expression of the oxidative stress regulator OxyR, since a mutant strain lacking RpoS failed to induce oxyR expression both during normal growth and under conditions of oxidative stress. It is further demonstrated that the RpoS acts as a positive transcriptional regulator of oxyR and dpsA expression, while OxyR acts as a negative transcriptional regulator of the katG-dpsA operon via OxyR repressor under normal growth conditions, and as a positive transcriptional regulator via OxyR under conditions of oxidative stress. Therefore both RpoS and OxyR are required to promote expression of both the katG-dpsA operon and dpsA gene.

RNA Sequencing Reveals Differences between the Global Transcriptomes of Salmonella enterica Serovar Enteritidis Strains with High and Low Pathogenicities

“…The heme containing Bfr is maximally expressed when Fe is abundant and accounts for the majority of stored Fe (109). While inactivation of bfr elevates the intracellular free Fe concentration and enhances susceptibility to H 2 O 2 stress, the DNA-binding protein Dps provides protection from oxidative damage without affecting the steady-state intracellular free Fe concentration, and it is also known to be induced during oxidative stress in Burkholderia pseudomallei, thereby protecting this pathogen from organic hydroperoxides and aiding its intramacrophage survival (110,111). Taken together, the reduced expression of several genes involved in resistance of Salmonella to osmotic and oxidative stresses and iron-limiting conditions correlates with the impaired survival of LP strains under oxidative and acidic stress as well as reduced intramacrophage survival (18).…”

Melioidosis: molecular aspects of pathogenesis

“…In addition to providing protection against oxidative stress, AhpC also helps B. pseudomallei to evade killing by RNI [96]. Expression of these genes ( katG , dpsA and ahpC ) was shown to be dependent on the global regulator OxyR, and consistent with this, B. pseudomallei oxyR mutants were hypersensitive to H 2 O 2 [95-98]. …”

RpoS and oxidative stress conditions regulate succinyl‐CoA: 3‐ketoacid‐coenzyme A transferase (SCOT) expression in Burkholderia pseudomallei

“…Earlier studies of RpoS regulated proteins in B. pseudomallei have shown that the RpoS sigma factor plays a key role in stress response systems . In addition, it has been demonstrated that OxyR and DpsA, proteins involved in oxidative stress response, are regulatory target of RpoS . Here, a global approach was utilized to explore other B. pseudomallei proteins that respond to oxidative stress and are regulated by RpoS.…”

“…However, many bacteria can survive during oxidative stress conditions, exemplifying the important role of their oxidative stress response systems. Previous studies have reported that RpoS is one of the key regulators of the oxidative stress response in B. pseudomallei .…”

“…For example, in B. pseudomallei the activity of KatG and KatE catalase enzymes is increased after exposure to H 2 O 2 . Expression of the KatG enzyme is indirectly controlled by RpoS through its regulation of OxyR, another transcriptional regulator that plays a key role in the response to oxidative stress in bacteria . RpoS also regulates other proteins involved in the response to oxidative stress .…”