Interaction specificity, toxicity and regulation of a paralogous set of ParE/RelE‐family toxin–antitoxin systems

Fiebig, Aretha; Rojas, Cyd Marie Castro; Siegal-Gaskins, Dan; Crosson, Sean

doi:10.1111/j.1365-2958.2010.07207.x

Cited by 95 publications

(117 citation statements)

References 48 publications

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“…Besides our analyses of the chromosomal V. cholerae parDE loci presented here, studies of chromosomal parDE loci in C. crescentus and E. coli O157:H7 have recently been reported (7,11,19). Multiple parE homologs are also present in these Gram-negative organisms, although two of the E. coli O157 antitoxins for ParE, designated PaaA, are not homologues of ParD.…”

Section: Discussionmentioning

confidence: 60%

“…1B), these findings suggest that these proteins have specificity both as regulators and as toxinneutralizing agents. Studies of paralogous TA loci in other organisms, including a study of three paralogous parDE loci in Caulobacter crescentus, have also failed to detect evidence for cross talk between antitoxins and toxins encoded by distinct but paralogous TA loci (4,11).…”

Section: Resultsmentioning

confidence: 99%

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The ThreeVibrio choleraeChromosome II-Encoded ParE Toxins Degrade Chromosome I following Loss of Chromosome II

2011

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Three homologues of the plasmid RK2 ParDE toxin-antitoxin system are present in the Vibrio cholerae genome within the superintegron on chromosome II. Here we found that these three loci-two of which have identical open reading frames and regulatory sequences-encode functional toxin-antitoxin systems. The ParE toxins inhibit bacterial division and reduce viability, presumably due to their capacity to damage DNA. The in vivo effects of ParE1/3 mimic those of ParE2, which we have previously demonstrated to be a DNA gyrase inhibitor in vitro, suggesting that ParE1/3 is likewise a gyrase inhibitor, despite its relatively low degree of sequence identity. ParE-mediated DNA damage activates the V. cholerae SOS response, which in turn likely accounts for ParE's inhibition of cell division. Each toxin's effects can be prevented by the expression of its cognate ParD antitoxin, which acts in a toxin-specific fashion both to block toxicity and to repress the expression of its parDE operon. Derepression of ParE activity in ⌬parAB2 mutant V. cholerae cells that have lost chromosome II contributes to the prominent DNA degradation that accompanies the death of these cells. Overall, our findings suggest that the ParE toxins lead to the postsegregational killing of cells missing chromosome II in a manner that closely mimics postsegregational killing mediated by plasmid-encoded homologs. Thus, the parDE loci aid in the maintenance of the integrity of the V. cholerae superintegron and in ensuring the inheritance of chromosome II.

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Section: Discussionmentioning

confidence: 60%

Section: Resultsmentioning

confidence: 99%

The ThreeVibrio choleraeChromosome II-Encoded ParE Toxins Degrade Chromosome I following Loss of Chromosome II

2011

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“…pNPTS138 carries the nptI gene to select for single integrants on kanamycin and the sacB gene for counterselection on sucrose. Transformation of C. crescentus and sucrose counterselection for allelic replacement were carried out as described previously (38). PCR and Sanger sequencing of the PCR product confirmed allele replacement.…”

Section: Methodsmentioning

confidence: 99%

“…Ten microliters of supernatant was mixed with 3 μL of SDS loading buffer, incubated at 95°C for 5 min, resolved on a 14% SDS/PAGE gel, and blotted onto a 0.2-μM PVDF membrane (Millipore). Blotting and antibody incubation were performed as previously described (38). Briefly, after transfer and blocking steps, the membrane was incubated with a mix of mouse monoclonal anti-HA (Sigma-Aldrich) and rabbit polyclonal anti-FixJ (loading control) primary antibodies.…”

Section: Methodsmentioning

confidence: 99%

Structural basis of a protein partner switch that regulates the general stress response of α-proteobacteria

Herrou¹,

Rotskoff²,

Luo³

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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α-Proteobacteria uniquely integrate features of two-component signal transduction (TCS) and alternative sigma factor (σ) regulation to control transcription in response to general stress. The core of this regulatory system is the PhyR protein, which contains a σ-like (SL) domain and a TCS receiver domain. Aspartyl phosphorylation of the PhyR receiver in response to stress signals promotes binding of the anti-σ factor, NepR, to PhyR-SL. This mechanism, whereby NepR switches binding between its cognate σ factor and phospho-PhyR (PhyR∼P), controls transcription of the general stress regulon. We have defined the structural basis of the PhyR∼P/NepR interaction in Caulobacter crescentus and characterized the effect of aspartyl phosphorylation on PhyR structure by molecular dynamics simulations. Our data support a model in which phosphorylation of the PhyR receiver domain promotes its dissociation from the PhyR-SL domain, which exposes the NepR binding site. A highly dynamic loop–helix region (α3-α4) of the PhyR-SL domain plays an important role in PhyR∼P binding to NepR in vitro, and in stress-dependent activation of transcription in vivo. This study provides a foundation for understanding the protein-protein interactions and protein structural dynamics that underpin general stress adaptation in a large and metabolically diverse clade of the bacterial kingdom.

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“…Various roles have been attributed to TA modules, including selfish entities and the stabilization of labile chromosomal segments (Magnuson, 2007;Van Melderen, 2010). Most researchers nevertheless agree on an involvement in stress response, given that various internal and external stresses lead to their activation (Christensen et al, 2001;Amitai et al, 2009;Kolodkin-Gal et al, 2009) and that at least in some cases differential activation is observed based on the type of stress encountered (Fiebig et al, 2010). However, since knocking out of individual TA modules does not seem to affect bacterial survival upon stress exposure in most bacteria, this may be a secondary effect (Tsilibaris et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

The ParE2–PaaA2 toxin–antitoxin complex fromEscherichia coliO157 forms a heterodocecamer in solution and in the crystal

et al. 2012

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Escherichia coli O157 paaR2-paaA2-parE2 constitutes a unique threecomponent toxin-antitoxin (TA) module encoding a toxin (ParE2) related to the classic parDE family but with an unrelated antitoxin called PaaA2. The complex between PaaA2 and ParE2 was purified and characterized by analytical gel filtration, dynamic light scattering and small-angle X-ray scattering. It consists of a particle with a radius of gyration of 3.95 nm and is likely to form a heterododecamer. Crystals of the ParE2-PaaA2 complex diffract to 3.8 Å resolution and belong to space group P3 1 21 or P3 2 21, with unit-cell parameters a = b = 142.9, c = 87.5 Å . The asymmetric unit is consistent with a particle of around 125 kDa, which is compatible with the solution data. Therefore, the ParE2-PaaA2 complex is the largest toxin-antitoxin complex identified to date and its quaternary arrangement is likely to be of biological significance.

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Interaction specificity, toxicity and regulation of a paralogous set of ParE/RelE‐family toxin–antitoxin systems

Cited by 95 publications

References 48 publications

The ThreeVibrio choleraeChromosome II-Encoded ParE Toxins Degrade Chromosome I following Loss of Chromosome II

The ThreeVibrio choleraeChromosome II-Encoded ParE Toxins Degrade Chromosome I following Loss of Chromosome II

Structural basis of a protein partner switch that regulates the general stress response of α-proteobacteria

The ParE2–PaaA2 toxin–antitoxin complex fromEscherichia coliO157 forms a heterodocecamer in solution and in the crystal

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