The MerR/NmlR Family Transcription Factor of
            <i>Streptococcus pneumoniae</i>
            Responds to Carbonyl Stress and Modulates Hydrogen Peroxide Production

Potter, Adam J.; Kidd, Stephen P.; McEwan, Alastair G.; Paton, James C.

doi:10.1128/jb.00383-10

Cited by 23 publications

(34 citation statements)

References 21 publications

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“…Many predicted mRNA targets found in this study also encode proteins that contribute to radiation survival, such as RecA, RuvA, and RadA (33,39,70). Other mRNAs do not encode proteins directly associated with DNA repair but are associated with stress response mechanisms or global gene regulation, such as the TetR family transcriptional regulator DR_0074, the cyclic AMP receptor protein (CRP)/ferredoxin-NADP ϩ reductase (FNR) family transcriptional regulator DR_ 0097, and the MerR family transcriptional regulator (71)(72)(73). geothermalis.…”

Section: Discussionmentioning

confidence: 99%

Transcriptional Analysis of Deinococcus radiodurans Reveals Novel Small RNAs That Are Differentially Expressed under Ionizing Radiation

Tsai

Liao

Chou

et al. 2015

Appl Environ Microbiol

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bSmall noncoding RNAs (sRNAs) are posttranscriptional regulators that have been identified in multiple species and shown to play essential roles in responsive mechanisms to environmental stresses. The natural ability of specific bacteria to resist high levels of radiation has been of high interest to mechanistic studies of DNA repair and biomolecular protection. Deinococcus radiodurans is a model extremophile for radiation studies that can survive doses of ionizing radiation of >12,000 Gy, 3,000 times higher than for most vertebrates. Few studies have investigated posttranscriptional regulatory mechanisms of this organism that could be relevant in its general gene regulatory patterns. In this study, we identified 199 potential sRNA candidates in D. radiodurans by whole-transcriptome deep sequencing analysis and confirmed the expression of 41 sRNAs by Northern blotting and reverse transcriptase PCR (RT-PCR). A total of 8 confirmed sRNAs showed differential expression during recovery after acute ionizing radiation (15 kGy). We have also found and confirmed 7 sRNAs in Deinococcus geothermalis, a closely related radioresistant species. The identification of several novel sRNAs in Deinococcus bacteria raises important questions about the evolution and nature of global gene regulation in radioresistance.

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Section: Discussionmentioning

confidence: 99%

Transcriptional Analysis of Deinococcus radiodurans Reveals Novel Small RNAs That Are Differentially Expressed under Ionizing Radiation

Tsai

Liao

Chou

et al. 2015

Appl Environ Microbiol

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“…As this organism lacks proteins that have been shown to protect against oxidative stress (e.g., catalase) (10), several studies focused on pneumococcal H 2 O 2 resistance (34,37,42). This resistance is important not only for the oxidative stress response of the pathogen but also for pneumococcal physiology (7,36) and pneumococcal interactions with other bacteria (24,33,40) and the host (12,13,35). Although it had been speculated that tpxD (psaD) encodes a pneumococcal thiol peroxidase, this is the first report that established the identity of the protein by direct enzymatic assays, demonstrated its mechanism of action, and showed that TpxD expression is regulated in response to H 2 O 2 levels.…”

Section: Discussionmentioning

confidence: 99%

Thiol Peroxidase Is an Important Component of Streptococcus pneumoniae in Oxygenated Environments

et al. 2012

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is formed, confirming the thiol peroxidase activity. Levels of TpxD expression and synthesis in vitro were significantly increased in cells grown under aerobic versus anaerobic conditions. The challenge with D39 and TIGR4 with H 2 O 2 resulted in tpxD upregulation, while psaBCA expression was oppositely affected. However, the challenge of ⌬tpxD mutants with H 2 O 2 did not affect psaBCA, implying that TpxD is involved in the regulation of the psa operon, in addition to its scavenging activity. Virulence studies demonstrated a notable difference in the survival time of mice infected intranasally with D39 compared to that of mice infected intranasally with D39⌬tpxD. However, when bacteria were administered directly into the blood, this difference disappeared. The findings of this study suggest that TpxD constitutes a component of the organism's fundamental strategy to fine-tune cellular processes in response to H 2 O 2 .

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“…However, all mutants had survival rates similar to that of the wild-type strain following paraquat and low-pH exposure. Also, the pneumococcus might employ polyamine-mediated defence mechanisms to overcome nitrosative stress during infection, as described for E. coli via the merR transcriptional regulator (Bower et al, 2009;Potter et al, 2010). Thus, subtle perturbations in intracellular polyamine levels may not significantly affect pneumococcal stress responses in vitro.…”

Section: Role Of Polyamines In Pneumococcal Diseasementioning

confidence: 99%

Polyamine biosynthesis and transport mechanisms are crucial for fitness and pathogenesis of Streptococcus pneumoniae

et al. 2011

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Polyamines such as cadaverine, putrescine and spermidine are polycationic molecules that have pleiotropic effects on cells via their interaction with nucleic acids. Streptococcus pneumoniae (the pneumococcus) is a Gram-positive pathogen capable of causing pneumonia, septicaemia, otitis media and meningitis. Pneumococci have a polyamine transport operon (potABCD) responsible for the binding and transport of putrescine and spermidine, and can synthesize cadaverine and spermidine using their lysine decarboxylase (cad) and spermidine synthase (speE) enzymes. Previous studies from our laboratory have shown that an increase in PotD expression is seen following exposure to various stresses, while during infection, potD inactivation significantly attenuates pneumococcal virulence, and anti-PotD immune responses are protective in mice. In spite of their relative importance, not much is known about the global contribution of polyamine biosynthesis and transport pathways to pneumococcal disease. Mutants deficient in polyamine biosynthesis (DspeE or Dcad) or transport genes (DpotABCD) were constructed and were found to be attenuated in murine models of pneumococcal colonization and pneumonia, either alone or in competition with the wild-type strain. The DspeE mutant was also attenuated during invasive disease, while the potABCD and cad genes seemed to be dispensable. HPLC analyses showed reduced intracellular polyamine levels in all mutant strains compared with wild-type bacteria. Highthroughput proteomic analyses indicated reduced expression of growth, replication and virulence factors in mutant strains. Thus, polyamine biosynthesis and transport mechanisms are intricately linked to the fitness, survival and pathogenesis of the pneumococcus in host microenvironments, and may represent important targets for prophylactic and therapeutic interventions.

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The MerR/NmlR Family Transcription Factor of Streptococcus pneumoniae Responds to Carbonyl Stress and Modulates Hydrogen Peroxide Production

Cited by 23 publications

References 21 publications

Transcriptional Analysis of Deinococcus radiodurans Reveals Novel Small RNAs That Are Differentially Expressed under Ionizing Radiation

Transcriptional Analysis of Deinococcus radiodurans Reveals Novel Small RNAs That Are Differentially Expressed under Ionizing Radiation

Thiol Peroxidase Is an Important Component of Streptococcus pneumoniae in Oxygenated Environments

Polyamine biosynthesis and transport mechanisms are crucial for fitness and pathogenesis of Streptococcus pneumoniae

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