Transcriptional regulation of hemO encoding heme oxygenase in Clostridium perfringens

Hassan, Sufi; Ohtani, Kaori; Wang, Ruoyu; Yuan, Yonghui; Wang, Yun; Yamaguchi, Yumi; Shimizu, Tohru

doi:10.1007/s12275-009-0384-3

Cited by 19 publications

(9 citation statements)

References 26 publications

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“…In the presence of heme, hemO is upregulated, but it is downregulated in the presence of iron (39). The factors responsible for the iron-dependent downregulation of hemO have not been identified.…”

Section: Bacterial Heme Sensingmentioning

confidence: 99%

“…The factors responsible for the iron-dependent downregulation of hemO have not been identified. The VirSR TCS and the VirRregulated RNA (VR-RNA) contribute to the positive regulation of hemO and other C. perfringens virulence genes; however, the stimulus of VirSR is still unknown (39,65). It is likely that virulence factors are regulated in the presence of host factors, and it is possible that host heme might be such an environmental signal.…”

Section: Bacterial Heme Sensingmentioning

confidence: 99%

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Overcoming the Heme Paradox: Heme Toxicity and Tolerance in Bacterial Pathogens

2010

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Virtually all bacterial pathogens require iron to infect vertebrates. The most abundant source of iron within vertebrates is in the form of heme as a cofactor of hemoproteins. Many bacterial pathogens have elegant systems dedicated to the acquisition of heme from host hemoproteins. Once internalized, heme is either degraded to release free iron or used intact as a cofactor in catalases, cytochromes, and other bacterial hemoproteins. Paradoxically, the high redox potential of heme makes it a liability, as heme is toxic at high concentrations. Although a variety of mechanisms have been proposed to explain heme toxicity, the mechanisms by which heme kills bacteria are not well understood. Nonetheless, bacteria employ various strategies to protect against and eliminate heme toxicity. Factors involved in heme acquisition and detoxification have been found to contribute to virulence, underscoring the physiological relevance of heme stress during pathogenesis. Herein we describe the current understanding of the mechanisms of heme toxicity and how bacterial pathogens overcome the heme paradox during infection.

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Section: Bacterial Heme Sensingmentioning

confidence: 99%

Section: Bacterial Heme Sensingmentioning

confidence: 99%

Overcoming the Heme Paradox: Heme Toxicity and Tolerance in Bacterial Pathogens

2010

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“…However, 12 RRs have low similarity to proteins in other clostridia. Two RRs (CLC_0632 and CLC_1105) show homology (38 and 37% protein identity, respectively) to the VirR regulator, which is part of the Clostridium perfringens TCS VirR-VirS involved in the regulation of numerous toxins in this bacterium (Ba-Thein et al, 1996;Cheung et al, 2009;Cheung et al, 2010;Hassan et al, 2010;Ma et al, 2011;Ohtani et al, 2009;Ohtani et al, 2003;Okumura et al, 2008).…”

Section: Two-component Systems Are Involved In the Regulation Of Bontmentioning

confidence: 99%

Regulation of toxin synthesis in Clostridium botulinum and Clostridium tetani

Connan

Denève

Mazuet

et al. 2013

Toxicon

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Botulinum and tetanus neurotoxins are structurally and functionally related proteins that are potent inhibitors of neuroexocytosis. Botulinum neurotoxin (BoNT) associates with non-toxic proteins (ANTPs) to form complexes of various sizes, whereas tetanus toxin (TeNT) does not form any complex. The BoNT and ANTP genes are clustered in a DNA segment called the botulinum locus, which has different genomic localization (chromosome, plasmid, phage) in the various Clostridium botulinum types and subtypes. The botulinum locus genes are organized in two polycistronic operons (ntnh-bont and ha/orfX operons) transcribed in opposite orientations. A gene called botR lying between the two operons in C. botulinum type A encodes an alternative sigma factor which regulates positively the synthesis of BoNT and ANTPs at the late exponential growth phase and beginning of the stationary phase. In Clostridium tetani, the gene located immediately upstream of tent encodes a positive regulatory protein, TetR, which is related to BotR. C. botulinum and C. tetani genomes contain several two-component systems and predicted regulatory orphan genes. In C. botulinum type A, four two-component systems have been found that positively or negatively regulate the synthesis of BoNT and ANTPs independently of BotR/A. The synthesis of neurotoxin in Clostridia seems to be under the control of complex network of regulation.

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“…Consequently, organisms have evolved a variety of mechanisms to minimize toxic effects. Whereas some bacteria rely mostly on their oxygenase to degrade excess heme, such as Neisseria gonorrhoeae (Zhu et al , ) or Clostridium perfringens (Hassan et al , ), an alternative strategy can be found in the eukaryotic parasite Plasmodium s pp. which is capable to sequester excess heme in an insoluble substance called hemozoin (Fitch, ; Jani et al , ; Anzaldi and Skaar, ).…”

Section: Introductionmentioning

confidence: 99%

Toxic but tasty – temporal dynamics and network architecture of heme‐responsive two‐component signaling in Corynebacterium glutamicum

Keppel

Piepenbreier

Gätgens

et al. 2019

Molecular Microbiology

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SummaryHeme is an essential cofactor and alternative iron source for almost all bacterial species but may cause severe toxicity upon elevated levels and consequently, regulatory mechanisms coordinating heme homeostasis represent an important fitness trait. A remarkable scenario is found in several corynebacterial species, e.g. Corynebacterium glutamicum and Corynebacterium diphtheriae, which dedicate two paralogous, heme‐responsive two‐component systems, HrrSA and ChrSA, to cope with the Janus nature of heme. Here, we combined experimental reporter profiling with a quantitative mathematical model to understand how this particular regulatory network architecture shapes the dynamic response to heme. Our data revealed an instantaneous activation of the detoxification response (hrtBA) upon stimulus perception and we found that kinase activity of both kinases contribute to this fast onset. Furthermore, instant deactivation of the PhrtBA promoter is achieved by a strong ChrS phosphatase activity upon stimulus decline. While the activation of detoxification response is uncoupled from further factors, heme utilization is additionally governed by the global iron regulator DtxR integrating information on iron availability into the regulatory network. Altogether, our data provide comprehensive insights how TCS cross‐regulation and network hierarchy shape the temporal dynamics of detoxification (hrtBA) and utilization (hmuO) as part of a global homeostatic response to heme.

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Transcriptional regulation of hemO encoding heme oxygenase in Clostridium perfringens

Cited by 19 publications

References 26 publications

Overcoming the Heme Paradox: Heme Toxicity and Tolerance in Bacterial Pathogens

Overcoming the Heme Paradox: Heme Toxicity and Tolerance in Bacterial Pathogens

Regulation of toxin synthesis in Clostridium botulinum and Clostridium tetani

Toxic but tasty – temporal dynamics and network architecture of heme‐responsive two‐component signaling in Corynebacterium glutamicum

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