Plasmid copy-number control and better-than-random segregation genes of pSM19035 share a common regulator

Hoz, Ana Belén de la; Ayora, Silvia; Sitkiewicz, Izabela; Fernández, Silvia; Pankiewicz, Renata; Alonso, Juan C.; Cegłowski, Piotr

doi:10.1073/pnas.97.2.728

Cited by 137 publications

(181 citation statements)

References 36 publications

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“…All TA complexes that have been tested are subject to negative regulation at the transcriptional level (17). With some notable exceptions (12,13), the antitoxin is the principal repressor, with the toxin acting as a cofactor that can dramatically enhance DNA binding by the antitoxin, most likely via conformational changes induced in the antitoxin. The toxin alone exhibits no DNA-binding activity.…”

Section: Discussionmentioning

confidence: 99%

Influence of Operator Site Geometry on Transcriptional Control by the YefM-YoeB Toxin-Antitoxin Complex

Bailey

Hayes

2009

J Bacteriol

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YefM-YoeB is among the most prevalent and well-characterized toxin-antitoxin complexes. YoeB toxin is an endoribonuclease whose activity is inhibited by YefM antitoxin. The regions 5 of yefM-yoeB in diverse bacteria possess conserved sequence motifs that mediate transcriptional autorepression. The yefM-yoeB operator site arrangement is exemplified in Escherichia coli: a pair of palindromes with core hexamer motifs and a centerto-center distance of 12 bp overlap the yefM-yoeB promoter. YefM is an autorepressor that initially recognizes a long palindrome containing the core hexamer, followed by binding to a short repeat. YoeB corepressor greatly enhances the YefM-operator interaction. Scanning mutagenesis demonstrated that the short repeat is crucial for correct interaction of YefM-YoeB with the operator site in vivo and in vitro. Moreover, altering the relative positions of the two palindromes on the DNA helix abrogated YefM-YoeB cooperative interactions with the repeats: complex binding to the long repeat was maintained but was perturbed to the short repeat. Although YefM lacks a canonical DNA binding motif, dual conserved arginine residues embedded in a basic patch of the protein are crucial for operator recognition. Deciphering the molecular basis of toxin-antitoxin transcriptional control will provide key insights into toxin-antitoxin activation and function.

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Section: Discussionmentioning

confidence: 99%

Influence of Operator Site Geometry on Transcriptional Control by the YefM-YoeB Toxin-Antitoxin Complex

Bailey

Hayes

2009

J Bacteriol

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“…Their homologues, epsilon-zeta of plasmid pSM19035 together with its upstream gene omega, are a three-component TAS in which the transcription of the whole operon is regulated by the Omega repressor protein (36). Neither the Epsilon antitoxin nor the Zeta toxin is involved in the regulation of this operon, although there is a weak promoter detected upstream of the epsilon gene (20,35). Unlike the Epsilon antitoxin, PezA functions as a repressor that binds to a 56-bp-long palindrome sequence located upstream of the pezA gene.…”

Section: Genetic Organization and Transcriptional Regulationmentioning

confidence: 99%

Toxin-Antitoxin Genes of the Gram-Positive Pathogen Streptococcus pneumoniae: So Few and Yet So Many

Chan

Moreno-Córdoba

Yeo

et al. 2012

Microbiol Mol Biol Rev

127

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SUMMARYPneumococcal infections cause up to 2 million deaths annually and raise a large economic burden and thus constitute an important threat to mankind. Because of the increase in the antibiotic resistance ofStreptococcus pneumoniaeclinical isolates, there is an urgent need to find new antimicrobial approaches to triumph over pneumococcal infections. Toxin-antitoxin (TA) systems (TAS), which are present in most living bacteria but not in eukaryotes, have been proposed as an effective strategy to combat bacterial infections. Type II TAS comprise a stable toxin and a labile antitoxin that form an innocuous TA complex under normal conditions. Under stress conditions, TA synthesis will be triggered, resulting in the degradation of the labile antitoxin and the release of the toxin protein, which would poison the host cells. The three functional chromosomal TAS fromS. pneumoniaethat have been studied as well as their molecular characteristics are discussed in detail in this review. Furthermore, a meticulous bioinformatics search has been performed for 48 pneumococcal genomes that are found in public databases, and more putative TAS, homologous to well-characterized ones, have been revealed. Strikingly, several unusual putative TAS, in terms of components and genetic organizations previously not envisaged, have been discovered and are further discussed. Previously, we reported a novel finding in which a unique pneumococcal DNA signature, the BOX element, affected the regulation of the pneumococcalyefM-yoeBTAS. This BOX element has also been found in some of the other pneumococcal TAS. In this review, we also discuss possible relationships between some of the pneumococcal TAS with pathogenicity, competence, biofilm formation, persistence, and an interesting phenomenon called bistability.

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“…Although the partitioning process of eukaryotic chromosome DNA is well described (1), this fundamental process of the bacterial genome is poorly understood (2,3). Our knowledge about DNA partition in bacteria comes largely from studies of the segregation of low-copy-number plasmids, a process ensured by partition (par) systems (4). Virtually all the par systems are composed of three essential elements: a partition site on the DNA target, a partition site binding protein that forms a large partition complex on the DNA target, and a nucleoside triphosphatase (NTPase) that drives partition (5).…”

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confidence: 99%

A Novel Transcriptional Activator, tubX , Is Required for the Stability of Bacillus sphaericus Mosquitocidal Plasmid pBsph

Zhao

et al. 2014

J Bacteriol

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bStable maintenance of the low-copy-number plasmid pBsph in Bacillus sphaericus requires a partitioning (par) system that consists of a filament-forming protein, B. sphaericus TubZ (TubZ-Bs); a centromere-binding protein, TubR-Bs; and a centromerelike DNA site, tubC, composed of three blocks (I, II, and III) of 12-bp degenerate repeats. Previous studies have shown that minipBsph replicons encoding the TubZ system are segregationally highly unstable, whereas the native pBsph is stably maintained. However, the mechanism underlying the stability discrepancy between pBsph and its minireplicon is poorly understood. Here orf187 (encoding TubX), a gene downstream of tubZ-Bs, was found to play a role in plasmid stabilization. Null mutation or overexpression of tubX resulted in a defect in pBsph stability and a significant decrease in the level of tubRZ-Bs expression, and the TubX-null phenotype was suppressed by ectopic expression of a wild-type copy of tubX and additional tubRZ-Bs. An electrophoresis mobility shift assay (EMSA) and a DNase I footprinting assay revealed that the TubX protein bound directly to five 8-bp degenerate repeats located in the par promoter region and that TubX competed with TubR-Bs for binding to the par promoter. Further studies demonstrated that TubX significantly stimulated the transcription of the par operon in the absence of tubR-Bs, and a higher level of gene activation was observed when tubR-Bs was present. These results suggested that TubX positively regulates tubRZ-Bs transcription by interfering with TubR-Bs-mediated repression and binding directly to the tubRZ-Bs promoter region.

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Plasmid copy-number control and better-than-random segregation genes of pSM19035 share a common regulator

Cited by 137 publications

References 36 publications

Influence of Operator Site Geometry on Transcriptional Control by the YefM-YoeB Toxin-Antitoxin Complex

Influence of Operator Site Geometry on Transcriptional Control by the YefM-YoeB Toxin-Antitoxin Complex

Toxin-Antitoxin Genes of the Gram-Positive Pathogen Streptococcus pneumoniae: So Few and Yet So Many

A Novel Transcriptional Activator, tubX , Is Required for the Stability of Bacillus sphaericus Mosquitocidal Plasmid pBsph

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