The anti-toxin ParD of plasmid RK2 consists of two structurally distinct moieties and belongs to the ribbon-helix-helix family of DNA-binding proteins

Oberer, Monika; Zangger, Klaus; PRYTULLA, Stefan; Keller, Walter

doi:10.1042/bj3610041

Cited by 31 publications

(31 citation statements)

References 37 publications

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“…10 shows that, according to the criterion introduced by Uversky (51,52,54) and Uversky et al (53), the addiction antitoxins in the monomeric form have a high tendency to be partially unstructured, whereas the corresponding toxins tend to be structured even as monomers. The prediction of structuring based on the mean hydrophobicity and mean net charge of the protein polypeptide chain is in good agreement with our observations and with recently reported results on addiction modules (11,47,89,90,102). Moreover, the large amount of the random-coil form found in free antitoxins in solutions (11,47,89,90,102) represents high vulnerability for their proteolytic cleavage (25,101,103).…”

Section: Discussionsupporting

confidence: 80%

Energetics of Structural Transitions of the Addiction Antitoxin MazE

Lah

Simic

Vesnaver

et al. 2005

Journal of Biological Chemistry

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The Escherichia coli mazEF addiction module plays a crucial role in the cell death program that is triggered under various stress conditions. It codes for the toxin MazF and the antitoxin MazE, which interferes with the lethal action of the toxin. To better understand the role of various conformations of MazE in bacterial life, its order-disorder transitions were monitored by differential scanning calorimetry, spectropolarimetry, and fluorimetry. The changes in spectral and thermodynamic properties accompanying MazE dimer denaturation can be described in terms of a compensating reversible process of the partial folding of the unstructured C-terminal half (high mean net charge, low mean hydrophobicity) and monomerization coupled with the partial unfolding of the structured N-terminal half (low mean net charge, high mean hydrophobicity). At pH < 4.5 and T < 50°C, the unstructured polypeptide chains of the MazE dimer fold into (pre)molten globule-like conformations that thermally stabilize the dimeric form of the protein. The simulation based on the thermodynamic and structural information on various addiction modules suggests that both the conformational adaptability of the dimeric antitoxin form (binding to the toxins and DNA) and the reversible transformation to the more flexible monomeric form are essential for the regulation of bacterial cell life and death.

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Section: Discussionsupporting

confidence: 80%

Energetics of Structural Transitions of the Addiction Antitoxin MazE

Lah

Simic

Vesnaver

et al. 2005

Journal of Biological Chemistry

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“…However, the various ParD antitoxins may bind to and inhibit the activity of their cognate ParE toxins in distinct ways. The C-terminal ParE-interacting domain of ParD RK2 is unfolded (38,39,47) and only becomes structured upon interaction with ParE. In contrast, C. crescentus ParD1, which forms a heterotetrameric complex with ParE1 in solution and in the ParD1-ParE1 crystal, is well structured in the absence of ParE1 (7).…”

Section: Discussionmentioning

confidence: 97%

“…Purified ParD RK2 , acting as a dimer, binds to its promoter and directly interferes with the binding of RNA polymerase (47). Since V. cholerae ParD1 and ParD2 are predicted to contain N-terminal ribbon-helix-helix DNA binding domains like that present in ParD RK2 (39), it seems probable that these V. cholerae antitoxins also directly bind and repress their respective promoters. However, the various ParD antitoxins may bind to and inhibit the activity of their cognate ParE toxins in distinct ways.…”

Section: Discussionmentioning

confidence: 99%

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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“…Members of the RHH family are much smaller proteins, ranging from the 45-residue CopG repressor to the 133-residue NikR from E. coli, with variations caused by additional N-or C-terminal domains (17,30). Examples of C-terminal functional regions in RHH members include protein tetramerization in the Mnt repressor, binding of the corepressor S-adenosylmethionine in MetJ, binding of the ParE toxin protein in the ParD repressor, and nickel binding by the repressor NikR (31)(32)(33)(34)(35)(36). In NikR, a C-terminal nickel-binding domain is attached to an N-terminal RHH fold (36).…”

Section: Discussionmentioning

confidence: 99%

Identification and Characterization of the DNA-binding Domain of the Multifunctional PutA Flavoenzyme

Zhou

Kallhoff

et al. 2004

Journal of Biological Chemistry

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The PutA flavoprotein from Escherichia coli is a transcriptional repressor and a bifunctional enzyme that regulates and catalyzes proline oxidation. PutA represses transcription of genes putA and putP by binding to the control DNA region of the put regulon. The objective of this study is to define and characterize the DNA binding domain of PutA. The DNA binding activity of PutA, a 1320 amino acid polypeptide, has been localized to N-terminal residues 1-261. After exploring a potential DNA-binding region and an N-terminal deletion mutant of PutA, residues 1-90 (PutA90) were determined to contain DNA binding activity and stabilize the dimeric structure of PutA. Cell-based transcriptional assays demonstrate that PutA90 functions as a transcriptional repressor in vivo. The dissociation constant of PutA90 with the put control DNA was estimated to be 110 nM, which is slightly higher than that of the PutA-DNA complex (K d ϳ 45 nM). Primary and secondary structure analysis of PutA90 suggested the presence of a ribbonhelix-helix DNA binding motif in residues 1-47. To test this prediction, we purified and characterized PutA47. PutA47 is shown to purify as an apparent dimer, to exhibit in vivo transcriptional activity, and to bind specifically to the put control DNA. In gel-mobility shift assays, PutA47 was observed to bind cooperatively to the put control DNA with an overall dissociation constant of 15 nM for the PutA47-DNA complex. Thus, Nterminal residues 1-47 are critical for DNA-binding and the dimeric structure of PutA. These results are consistent with the ribbon-helix-helix family of transcription factors.

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The anti-toxin ParD of plasmid RK2 consists of two structurally distinct moieties and belongs to the ribbon-helix-helix family of DNA-binding proteins

Cited by 31 publications

References 37 publications

Energetics of Structural Transitions of the Addiction Antitoxin MazE

Energetics of Structural Transitions of the Addiction Antitoxin MazE

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

Identification and Characterization of the DNA-binding Domain of the Multifunctional PutA Flavoenzyme

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