ppGpp and DksA likely regulate the activity of the extracytoplasmic stress factor σ<sup>E</sup> in <i>Escherichia coli</i> by both direct and indirect mechanisms

Costanzo, Alessandra; Nicoloff, Hervé; Barchinger, Sarah E.; Banta, Amy B.; Gourse, Richard L.; Ades, Sarah E.

doi:10.1111/j.1365-2958.2007.06072.x

Cited by 115 publications

(132 citation statements)

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“…This result is similar to that in E. coli, where s E is activated upon entry into stationary phase, due to starvation, by the alarmone ppGpp, even if its cognate anti-s factor is inactivated (Costanzo & Ades, 2006;Costanzo et al, 2008). Therefore, stationary phase could be one of the conditions during which rpoE is activated only in anti-s mutants of A. brasilense.…”

Section: Discussionsupporting

confidence: 67%

An extra-cytoplasmic function sigma factor and anti-sigma factor control carotenoid biosynthesis in Azospirillum brasilense

et al. 2008

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Strains Sp7 and Cd of Azospirillum brasilense, a plant growth-promoting rhizobacterium, differ in synthesis of carotenoids. While colonies of strain Sp7 have a white-cream colour on plates, colonies of strain Cd are orange-pink coloured because of the synthesis of carotenoids. Screening of a mini-Tn5 mutant library of A. brasilense Sp7 revealed two orange-pink-coloured mutants that produced carotenoids. Cloning and sequencing of the Tn5 flanking region in both the carotenoid-producing mutants of Sp7 revealed insertion of Tn5 in an ORF encoding anti-s factor, a ChrR-like protein.

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Section: Discussionsupporting

confidence: 67%

An extra-cytoplasmic function sigma factor and anti-sigma factor control carotenoid biosynthesis in Azospirillum brasilense

et al. 2008

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“…Empty vector controls were included when plasmid constructs were used in experiments. In order to determine the growth phase-dependent regulation (i.e., kinetics) and the rate of expression of gene fusions, we used differential plots as previously described (14,15,31,44). This was accomplished by monitoring the growth of the culture (from an initial OD 600 of 0.02 to an OD 600 of ϳ1) and the reporter activity (U ml Ϫ1 ) in the growing cultures.…”

Section: Methodsmentioning

confidence: 99%

Fur Negatively Regulates hns and Is Required for the Expression of HilA and Virulence in Salmonella enterica Serovar Typhimurium

et al. 2011

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Iron is an essential element for the survival of living cells. However, excess iron is toxic, and its uptake is exquisitely regulated by the ferric uptake regulator, Fur. In Salmonella, the Salmonella pathogenicity island 1 (SPI-1) encodes a type three secretion system, which is required for invasion of host epithelial cells in the small intestine. A major activator of SPI-1 is HilA, which is encoded within SPI-1. One known regulator of hilA is Fur. The mechanism of hilA regulation by Fur is unknown. We report here that Fur is required for virulence in Salmonella enterica serovar Typhimurium and that Fur is required for the activation of hilA, as well as of other HilA-dependent genes, invF and sipC. The Fur-dependent regulation of hilA was independent of PhoP, a known repressor of hilA. Instead, the expression of the gene coding for the histone-like protein, hns, was significantly derepressed in the fur mutant. Indeed, the activation of hilA by Fur was dependent on 28 nucleotides located upstream of hns. Moreover, we used chromatin immunoprecipitation to show that Fur bound, in vivo, to the upstream region of hns in a metal-dependent fashion. Finally, deletion of fur in an hns mutant resulted in Fur-independent activation of hilA. In conclusion, Fur activates hilA by repressing the expression of hns.

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“…In gammaproteobacteria, nearly all direct targets of ppGpp require the vegetative housekeeping sigma factor 70 . During a stringent response, alarmone inhibition of strong 70 -dependent promoters, such as rRNA promoters, increases the availability of core RNAP for transcription by alternative sigma factors (20,49,80,194). In this manner, ppGpp indirectly promotes alternative sigma factor-dependent gene regulation by repressing the transcription of rRNA operons.…”

Section: Regulatory Targets Of Ppgppmentioning

confidence: 99%

ppGpp Conjures Bacterial Virulence

Dalebroux

Svensson

Gaynor

et al. 2010

Microbiol Mol Biol Rev

333

364

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SUMMARY Like for all microbes, the goal of every pathogen is to survive and replicate. However, to overcome the formidable defenses of their hosts, pathogens are also endowed with traits commonly associated with virulence, such as surface attachment, cell or tissue invasion, and transmission. Numerous pathogens couple their specific virulence pathways with more general adaptations, like stress resistance, by integrating dedicated regulators with global signaling networks. In particular, many of nature's most dreaded bacteria rely on nucleotide alarmones to cue metabolic disturbances and coordinate survival and virulence programs. Here we discuss how components of the stringent response contribute to the virulence of a wide variety of pathogenic bacteria.

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ppGpp and DksA likely regulate the activity of the extracytoplasmic stress factor σ^E in Escherichia coli by both direct and indirect mechanisms

Cited by 115 publications

References 50 publications

An extra-cytoplasmic function sigma factor and anti-sigma factor control carotenoid biosynthesis in Azospirillum brasilense

An extra-cytoplasmic function sigma factor and anti-sigma factor control carotenoid biosynthesis in Azospirillum brasilense

Fur Negatively Regulates hns and Is Required for the Expression of HilA and Virulence in Salmonella enterica Serovar Typhimurium

ppGpp Conjures Bacterial Virulence

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ppGpp and DksA likely regulate the activity of the extracytoplasmic stress factor σE in Escherichia coli by both direct and indirect mechanisms

Cited by 115 publications

References 50 publications

An extra-cytoplasmic function sigma factor and anti-sigma factor control carotenoid biosynthesis in Azospirillum brasilense

An extra-cytoplasmic function sigma factor and anti-sigma factor control carotenoid biosynthesis in Azospirillum brasilense

Fur Negatively Regulates hns and Is Required for the Expression of HilA and Virulence in Salmonella enterica Serovar Typhimurium

ppGpp Conjures Bacterial Virulence

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ppGpp and DksA likely regulate the activity of the extracytoplasmic stress factor σ^E in Escherichia coli by both direct and indirect mechanisms