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DegS and RseP homologous proteases are involved in singlet oxygen dependent activation of RpoE in Rhodobacter sphaeroides.

Nuss AM, Adnan F, Weber L, Berghoff BA, Glaeser J, Klug G - PLoS ONE (2013)

Bottom Line: Moreover, we revealed that the DegS and RseP homologs RSP_3242 and RSP_2710 contribute to (1)O2 resistance and promote ChrR proteolysis.The RpoE signaling pathway in R. sphaeroides is therefore highly similar to that of Escherichia coli, although very different anti-sigma factors control RpoE activity.Based on the acquired results, the current model for RpoE activation in response to (1)O2 exposure in R. sphaeroides was extended.

View Article: PubMed Central - PubMed

Affiliation: Institute of Microbiology and Molecular Biology, Giessen University, Giessen, Germany ; Department of Molecular Infection Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany.

ABSTRACT
Singlet oxygen ((1)O2) is the main agent of photooxidative stress and is generated by photosensitizers as (bacterio)chlorophylls. It leads to the damage of cellular macromolecules and therefore photosynthetic organisms have to mount an adaptive response to (1)O2 formation. A major player of the photooxidative stress response in Rhodobacter sphaeroides is the alternative sigma factor RpoE, which is inactivated under non-stress conditions by its cognate anti-sigma factor ChrR. By using random mutagenesis we identified RSP_1090 to be required for full activation of the RpoE response under (1)O2 stress, but not under organic peroxide stress. In this study we show that both RSP_1090 and RSP_1091 are required for full resistance towards (1)O2. Moreover, we revealed that the DegS and RseP homologs RSP_3242 and RSP_2710 contribute to (1)O2 resistance and promote ChrR proteolysis. The RpoE signaling pathway in R. sphaeroides is therefore highly similar to that of Escherichia coli, although very different anti-sigma factors control RpoE activity. Based on the acquired results, the current model for RpoE activation in response to (1)O2 exposure in R. sphaeroides was extended.

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Current model of RpoE activation by ChrR proteolysis in R. sphaeroides under 1O2 stress.The model displays the mechanism of RpoE activation in the response to 1O2. The localization of ChrR at the membrane is speculative. Solid black arrows indicate positive effects. Dashed arrows indicate hypothetical effects. A detailed explanation is given in the conclusion part.
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pone-0079520-g010: Current model of RpoE activation by ChrR proteolysis in R. sphaeroides under 1O2 stress.The model displays the mechanism of RpoE activation in the response to 1O2. The localization of ChrR at the membrane is speculative. Solid black arrows indicate positive effects. Dashed arrows indicate hypothetical effects. A detailed explanation is given in the conclusion part.

Mentions: Our current model (Figure 10) shows the activation of RpoE in the response to photooxidative stress. Under non-stress conditions the ChrR proteolysis rate is low, but ensures a basal level and activity of RpoE in the cell. Upon exposure to 1O2, as well as organic peroxide stress, the anti-sigma factor ChrR is rapidly degraded. The 1O2 induced proteolysis requires RSP_1091 and RSP_1090 and involves at least two proteases, the DegS and RseP homologs RSP_3242 and RSP_2710. ChrR proteolysis leads to RpoE release, RpoE binds to the RNA-polymerase and induces target gene expression, including the rpoEchrR and the RSP_1091-1087 operon. Increased levels of RSP_1091 and RSP_1090 promote ongoing ChrR proteolysis to maintain high RpoE activity, which displays a positive regulatory loop. Activation of RpoE in the presence of organic peroxide does not require the DegS and RseP homologs RSP_3242 and RSP_2710 for ChrR proteolysis, but so far unknown proteases. In this study further components of the cascade involved in 1O2 signaling were identified, but the direct link between RSP_1091 and RSP_1090 and the proteases RSP_2710 and RSP_3242 in ChrR proteolysis and subsequent RpoE activation remain to be elucidated.


DegS and RseP homologous proteases are involved in singlet oxygen dependent activation of RpoE in Rhodobacter sphaeroides.

Nuss AM, Adnan F, Weber L, Berghoff BA, Glaeser J, Klug G - PLoS ONE (2013)

Current model of RpoE activation by ChrR proteolysis in R. sphaeroides under 1O2 stress.The model displays the mechanism of RpoE activation in the response to 1O2. The localization of ChrR at the membrane is speculative. Solid black arrows indicate positive effects. Dashed arrows indicate hypothetical effects. A detailed explanation is given in the conclusion part.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3818230&req=5

pone-0079520-g010: Current model of RpoE activation by ChrR proteolysis in R. sphaeroides under 1O2 stress.The model displays the mechanism of RpoE activation in the response to 1O2. The localization of ChrR at the membrane is speculative. Solid black arrows indicate positive effects. Dashed arrows indicate hypothetical effects. A detailed explanation is given in the conclusion part.
Mentions: Our current model (Figure 10) shows the activation of RpoE in the response to photooxidative stress. Under non-stress conditions the ChrR proteolysis rate is low, but ensures a basal level and activity of RpoE in the cell. Upon exposure to 1O2, as well as organic peroxide stress, the anti-sigma factor ChrR is rapidly degraded. The 1O2 induced proteolysis requires RSP_1091 and RSP_1090 and involves at least two proteases, the DegS and RseP homologs RSP_3242 and RSP_2710. ChrR proteolysis leads to RpoE release, RpoE binds to the RNA-polymerase and induces target gene expression, including the rpoEchrR and the RSP_1091-1087 operon. Increased levels of RSP_1091 and RSP_1090 promote ongoing ChrR proteolysis to maintain high RpoE activity, which displays a positive regulatory loop. Activation of RpoE in the presence of organic peroxide does not require the DegS and RseP homologs RSP_3242 and RSP_2710 for ChrR proteolysis, but so far unknown proteases. In this study further components of the cascade involved in 1O2 signaling were identified, but the direct link between RSP_1091 and RSP_1090 and the proteases RSP_2710 and RSP_3242 in ChrR proteolysis and subsequent RpoE activation remain to be elucidated.

Bottom Line: Moreover, we revealed that the DegS and RseP homologs RSP_3242 and RSP_2710 contribute to (1)O2 resistance and promote ChrR proteolysis.The RpoE signaling pathway in R. sphaeroides is therefore highly similar to that of Escherichia coli, although very different anti-sigma factors control RpoE activity.Based on the acquired results, the current model for RpoE activation in response to (1)O2 exposure in R. sphaeroides was extended.

View Article: PubMed Central - PubMed

Affiliation: Institute of Microbiology and Molecular Biology, Giessen University, Giessen, Germany ; Department of Molecular Infection Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany.

ABSTRACT
Singlet oxygen ((1)O2) is the main agent of photooxidative stress and is generated by photosensitizers as (bacterio)chlorophylls. It leads to the damage of cellular macromolecules and therefore photosynthetic organisms have to mount an adaptive response to (1)O2 formation. A major player of the photooxidative stress response in Rhodobacter sphaeroides is the alternative sigma factor RpoE, which is inactivated under non-stress conditions by its cognate anti-sigma factor ChrR. By using random mutagenesis we identified RSP_1090 to be required for full activation of the RpoE response under (1)O2 stress, but not under organic peroxide stress. In this study we show that both RSP_1090 and RSP_1091 are required for full resistance towards (1)O2. Moreover, we revealed that the DegS and RseP homologs RSP_3242 and RSP_2710 contribute to (1)O2 resistance and promote ChrR proteolysis. The RpoE signaling pathway in R. sphaeroides is therefore highly similar to that of Escherichia coli, although very different anti-sigma factors control RpoE activity. Based on the acquired results, the current model for RpoE activation in response to (1)O2 exposure in R. sphaeroides was extended.

Show MeSH
Related in: MedlinePlus