Plasmid Stabilization by Post-Segregational Killing

1997 ◽  
pp. 49-61 ◽  
Author(s):  
Kenn Gerdes ◽  
Jimmy Schouv Jacobsen ◽  
Thomas Franch
Keyword(s):  
Plasmid Stabilization

scholarly journals A peptide of a type I toxin−antitoxin system inducesHelicobacter pylorimorphological transformation from spiral shape to coccoids

2020 ◽  
Vol 117 (49) ◽  
pp. 31398-31409
Author(s):  
Lamya El Mortaji ◽  
Alejandro Tejada-Arranz ◽  
Aline Rifflet ◽  
Ivo G. Boneca ◽  
Gérard Pehau-Arnaudet ◽  
...  
Keyword(s):  
Antisense Rna ◽  
Type I ◽  
Morphological Transformation ◽  
Bacterial Chromosomes ◽  
Concentration Result ◽  
Expression Activity ◽  
Spiral Shape ◽  
H Pylori ◽  
Plasmid Stabilization

Toxin−antitoxin systems are found in many bacterial chromosomes and plasmids with roles ranging from plasmid stabilization to biofilm formation and persistence. In these systems, the expression/activity of the toxin is counteracted by an antitoxin, which, in type I systems, is an antisense RNA. While the regulatory mechanisms of these systems are mostly well defined, the toxins’ biological activity and expression conditions are less understood. Here, these questions were investigated for a type I toxin−antitoxin system (AapA1−IsoA1) expressed from the chromosome of the human pathogenHelicobacter pylori. We show that expression of the AapA1 toxin inH. pyloricauses growth arrest associated with rapid morphological transformation from spiral-shaped bacteria to round coccoid cells. Coccoids are observed in patients and during in vitro growth as a response to different stress conditions. The AapA1 toxin, first molecular effector of coccoids to be identified, targetsH. pyloriinner membrane without disrupting it, as visualized by cryoelectron microscopy. The peptidoglycan composition of coccoids is modified with respect to spiral bacteria. No major changes in membrane potential or adenosine 5′-triphosphate (ATP) concentration result from AapA1 expression, suggesting coccoid viability. Single-cell live microscopy tracking the shape conversion suggests a possible association of this process with cell elongation/division interference. Oxidative stress induces coccoid formation and is associated with repression of the antitoxin promoter and enhanced processing of its transcript, leading to an imbalance in favor of AapA1 toxin expression. Our data support the hypothesis of viable coccoids with characteristics of dormant bacteria that might be important inH. pyloriinfections refractory to treatment.

scholarly journals A peptide of a type I toxin-antitoxin system induces Helicobacter pylori morphological transformation from spiral-shape to coccoids

2019 ◽  
Author(s):  
Lamya El Mortaji ◽  
Alejandro Tejada-Arranz ◽  
Aline Rifflet ◽  
Ivo G Boneca ◽  
Gérard Pehau-Arnaudet ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Helicobacter Pylori ◽  
Membrane Integrity ◽  
Type I ◽  
Morphological Transformation ◽  
Bacterial Chromosomes ◽  
Concentration Result ◽  
H Pylori ◽  
Plasmid Stabilization

SummaryToxin-antitoxin systems are found in many bacterial chromosomes and plasmids with roles ranging from plasmid stabilization to biofilm formation and persistence. In these systems, the expression/activity of the toxin is counteracted by an antitoxin, which in type I systems is an antisense-RNA. While the regulatory mechanisms of these systems are mostly well-defined, the toxins’ biological activity and expression conditions are less understood. Here, these questions were investigated for a type I toxin-antitoxin system (AapA1-IsoA1) expressed from the chromosome of the human pathogen Helicobacter pylori. We show that expression of the AapA1 toxin in H. pylori causes growth arrest associated with rapid morphological transformation from spiral-shaped bacteria to round coccoid cells. Coccoids are observed in patients and during in vitro growth as a response to different stress conditions. The AapA1 toxin, first molecular effector of coccoids to be identified, targets H. pylori inner membrane without disrupting it, as visualized by Cryo-EM. The peptidoglycan composition of coccoids is modified with respect to spiral bacteria. No major changes in membrane potential or ATP concentration result from AapA1 expression, suggesting coccoid viability. Single-cell live microscopy tracking the shape conversion suggests a possible association of this process with cell elongation/division interference. Oxidative stress induces coccoid formation and is associated with repression of the antitoxin promoter and enhanced processing of its transcript, leading to an imbalance in favor of AapA1 toxin expression.Our data support the hypothesis of viable coccoids with characteristics of dormant bacteria that might be important in H. pylori infections refractory to treatment.Significance StatementHelicobacter pylori, a gastric pathogen causing 800,000 deaths in the world annually, is encountered both in vitro and in patients as spiral-shaped bacteria and as round cells named coccoids. We discovered that the toxin from a chromosomal type I toxin-antitoxin system is targeting H. pylori membrane and acting as an effector of H. pylori morphological conversion to coccoids. We showed that these round cells maintain their membrane integrity and metabolism, strongly suggesting that they are viable dormant bacteria. Oxidative stress was identified as a signal inducing toxin expression and coccoid formation. Our findings reveal new insights into a form of dormancy of this bacterium that might be associated with H. pylori infections refractory to treatment.

scholarly journals Identification of a Novel Plasmid Carrying mcr-4.3 in an Acinetobacter baumannii Strain in China

2019 ◽  
Vol 63 (6) ◽  
Author(s):  
Furong Ma ◽  
Cong Shen ◽  
Xiaobin Zheng ◽  
Yan Liu ◽  
Hongtao Chen ◽  
...  
Keyword(s):  
Gene Transfer ◽  
Horizontal Gene Transfer ◽  
Acinetobacter Baumannii ◽  
Guangdong Province ◽  
Type Ii ◽  
Content Type ◽  
Plasmid Stabilization

ABSTRACT Here, we identified mcr-4.3 in Acinetobacter baumannii, which had not been previously observed to carry an mcr gene. The mcr-4.3-harboring A. baumannii strain AB18PR065 was isolated from pig feces from a slaughterhouse in Guangdong Province of China. The mcr-4.3-carrying pAB18PR065 is 25,602 bp in size and could not be transferred in conjugation, transformation, and electroporation experiments, as we did not find any conjugation-related genes therein. pAB18PR065 harbors two copies of type II toxin-antitoxin systems, which are functional in plasmid stabilization and maintenance. pAB18PR065 shares similarity only with one recently identified plasmid, pAb-MCR4.3 (35,502 bp), from a clinical A. baumannii strain. It is likely that the emergence of pAb-MCR4.3 was due to the insertion of an 11,386-bp, ISAba19-based, composite transposon into pAB18PR065. These data indicate that mcr-4.3 was captured by an A. baumannii-original plasmid via horizontal gene transfer.

scholarly journals ParABS Systems of the Four Replicons of Burkholderia cenocepacia: New Chromosome Centromeres Confer Partition Specificity

2006 ◽  
Vol 188 (4) ◽  
pp. 1489-1496 ◽  
Author(s):  
Nelly Dubarry ◽  
Franck Pasta ◽  
David Lane
Keyword(s):  
Small Chromosome ◽  
Burkholderia Cenocepacia ◽  
Plasmid Partition ◽  
Copy Number Plasmid ◽  
Low Copy Number ◽  
Bacterial Chromosomes ◽  
Interacting Systems ◽  
Plasmid Stabilization ◽  
Main Chromosome ◽  
Independent Partition

ABSTRACT Most bacterial chromosomes carry an analogue of the parABS systems that govern plasmid partition, but their role in chromosome partition is ambiguous. parABS systems might be particularly important for orderly segregation of multipartite genomes, where their role may thus be easier to evaluate. We have characterized parABS systems in Burkholderia cenocepacia, whose genome comprises three chromosomes and one low-copy-number plasmid. A single parAB locus and a set of ParB-binding (parS) centromere sites are located near the origin of each replicon. ParA and ParB of the longest chromosome are phylogenetically similar to analogues in other multichromosome and monochromosome bacteria but are distinct from those of smaller chromosomes. The latter form subgroups that correspond to the taxa of their hosts, indicating evolution from plasmids. The parS sites on the smaller chromosomes and the plasmid are similar to the “universal” parS of the main chromosome but with a sequence specific to their replicon. In an Escherichia coli plasmid stabilization test, each parAB exhibits partition activity only with the parS of its own replicon. Hence, parABS function is based on the independent partition of individual chromosomes rather than on a single communal system or network of interacting systems. Stabilization by the smaller chromosome and plasmid systems was enhanced by mutation of parS sites and a promoter internal to their parAB operons, suggesting autoregulatory mechanisms. The small chromosome ParBs were found to silence transcription, a property relevant to autoregulation.

scholarly journals Antibiotic-free segregational plasmid stabilization in Escherichia coli owing to the knockout of triosephosphate isomerase (tpiA)

2014 ◽  
Vol 13 (1) ◽  
pp. 58 ◽  
Author(s):  
Ram Velur Selvamani ◽  
Maurice Telaar ◽  
Karl Friehs ◽  
Erwin Flaschel
Keyword(s):  
Escherichia Coli ◽  
Triosephosphate Isomerase ◽  
Plasmid Stabilization

scholarly journals Characterization of a higBA Toxin-Antitoxin Locus in Vibrio cholerae

2006 ◽  
Vol 189 (2) ◽  
pp. 491-500 ◽  
Author(s):  
Priya Prakash Budde ◽  
Brigid M. Davis ◽  
Jie Yuan ◽  
Matthew K. Waldor
Keyword(s):  
Escherichia Coli ◽  
Vibrio Cholerae ◽  
Free Living ◽  
Dependent Cell ◽  
Exogenous Expression ◽  
Biochemical Analyses ◽  
Chromosome Ii ◽  
Plasmid Stabilization ◽  
Living Bacteria

ABSTRACT Toxin-antitoxin (TA) loci, which were initially characterized as plasmid stabilization agents, have in recent years been detected on the chromosomes of numerous free-living bacteria. Vibrio cholerae, the causative agent of cholera, contains 13 putative TA loci, all of which are clustered within the superintegron on chromosome II. Here we report the characterization of the V. cholerae higBA locus, also known as VCA0391/2. Deletion of higA alone was not possible, consistent with predictions that it encodes an antitoxin, and biochemical analyses confirmed that HigA interacts with HigB. Transient exogenous expression of the toxin HigB dramatically slowed growth of V. cholerae and Escherichia coli and reduced the numbers of CFU by several orders of magnitude. HigB toxicity could be counteracted by simultaneous or delayed production of HigA, although HigA's effect diminished as the delay lengthened. Transcripts from endogenous higBA increased following treatment of V. cholerae with translational inhibitors, presumably due to reduced levels of HigA, which represses the higBA locus. However, no higBA-dependent cell death was observed in response to such stimuli. Thus, at least under the conditions tested, activation of endogenous HigB does not appear to be bactericidal.

scholarly journals Role of the parCBA Operon of the Broad-Host-Range Plasmid RK2 in Stable Plasmid Maintenance

1998 ◽  
Vol 180 (22) ◽  
pp. 6023-6030 ◽  
Author(s):  
Carla L. Easter ◽  
Helmut Schwab ◽  
Donald R. Helinski
Keyword(s):  
Host Range ◽  
Plasmid Stability ◽  
Broad Host Range ◽  
E Coli ◽  
Broad Host Range Plasmid ◽  
Resolution System ◽  
Stable Maintenance ◽  
Plasmid Stabilization ◽  
Plasmid Rk2

ABSTRACT The par region of the stably maintained broad-host-range plasmid RK2 is organized as two divergent operons,parCBA and parDE, and a cis-acting site. parDE encodes a postsegregational killing system, andparCBA encodes a resolvase (ParA), a nuclease (ParB), and a protein of unknown function (ParC). The present study was undertaken to further delineate the role of the parCBA region in the stable maintenance of RK2 by first introducing precise deletions in the three genes and then assessing the abilities of the different constructs to stabilize RK2 in three strains of Escherichia coli and two strains of Pseudomonas aeruginosa. The intact parCBA operon was effective in stabilizing a conjugation-defective RK2 derivative in E. coli MC1061K and RR1 but was relatively ineffective in E. coli MV10Δlac. In the two strains in which the parCBA operon was effective, deletions in parB, parC, or bothparB and parC caused an approximately twofold reduction in the stabilizing ability of the operon, while a deletion in the parA gene resulted in a much greater loss ofparCBA activity. For P. aeruginosaPAO1161Rifr, the parCBA operon provided little if any plasmid stability, but for P. aeruginosaPAC452Rifr, the RK2 plasmid was stabilized to a substantial extent by parCBA. With this latter strain, parAand res alone were sufficient for stabilization. Thecer resolvase system of plasmid ColE1 and theloxP/Cre system of plasmid P1 were tested in comparison with the parCBA operon. We found that, not unlike what was previously observed with MC1061K, cer failed to stabilize the RK2 plasmid with par deletions in strain MV10Δlac, but this multimer resolution system was effective in stabilizing the plasmid in strain RR1. The loxP/Cre system, on the other hand, was very effective in stabilizing the plasmid in all threeE. coli strains. These observations indicate that theparA gene, along with its res site, exhibits a significant level of plasmid stabilization in the absence of theparC and parB genes but that in at least oneE. coli strain, all three genes are required for maximum stabilization. It cannot be determined from these results whether or not the stabilization effects seen with parCBA or thecer and loxP/Cre systems are strictly due to a reduction in the level of RK2 dimers and an increase in the number of plasmid monomer units or if these systems play a role in a more complex process of plasmid stabilization that requires as an essential step the resolution of plasmid dimers.

A yeast mutation that stabilizes a plasmid bearing a mutated ARS1 element

1989 ◽  
Vol 9 (2) ◽  
pp. 809-816
Author(s):  
C Thrash-Bingham ◽  
W L Fangman
Keyword(s):  
Gene Disruption ◽  
Plasmid Stability ◽  
The Other ◽  
Wild Type ◽  
Minichromosome Maintenance ◽  
Autonomously Replicating Sequence ◽  
Plasmid Maintenance ◽  
Complementation Groups ◽  
The Stability ◽  
Plasmid Stabilization

To identify the trans-acting factors involved in autonomously replicating sequence (ARS) function, we initiated a screen for Saccharomyces cerevisiae mutants capable of stabilizing a plasmid that contains a defective ARS element. The amm (altered minichromosome maintenance) mutations recovered in this screen defined at least four complementation groups. amm1, a mutation that has been studied in detail, gave rise to a 17-fold stabilization of one defective ARS1 plasmid over the level seen in wild-type cells. The mutation also affected the stability of at least one plasmid bearing a wild-type ARS element. amm1 is an allele of the previously identified TUP1 gene and exhibited the same pleiotropic phenotypes as other tup1 mutants. Plasmid maintenance was also affected in strains bearing a TUP1 gene disruption. Like the amm1 mutant, the tup1 disruption mutant exhibited ARS-specific plasmid stabilization; however, the ARS specificities of these two mutants differed. The recovery of second-site mutations that suppressed many of the tup1 phenotypes but not the increased plasmid maintenance demonstrates that the plasmid stability phenotype of tup1 mutants is not a consequence of the other defects caused by tup1.

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