Ham22, a mini-F mutation which is lethal to host cell and promotes recA-dependent induction of lambdoid prophage.

Karoui, M.; Bex, Françoise; Dreze, Pierre Luc; Couturier, Martine

doi:10.1002/j.1460-2075.1983.tb01672.x

Cited by 67 publications

(38 citation statements)

References 26 publications

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“…S1 in the supplemental material). The lethal gene ccdB selected for the generation of the reporter plasmids was derived from the toxin-antitoxin locus ccdA-ccdB of the E. coli F plasmid encoding the cellkilling protein CcdB, which in the absence of CcdA inactivates gyrase and results in cell death (63)(64)(65). The gene was fused to the QS-controlled promoters P luxI of V. fischeri and P lsrA of E. coli, as outlined in Fig.…”

Section: Resultsmentioning

confidence: 99%

Novel Reporter for Identification of Interference with Acyl Homoserine Lactone and Autoinducer-2 Quorum Sensing

Weiland‐Bräuer

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Schmitz

2015

Appl Environ Microbiol

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Two reporter strains were established to identify novel biomolecules interfering with bacterial communication (quorum sensing [QS]). The basic design of these Escherichia coli-based systems comprises a gene encoding a lethal protein fused to promoters induced in the presence of QS signal molecules. Consequently, these E. coli strains are unable to grow in the presence of the respective QS signal molecules unless a nontoxic QS-interfering compound is present. The first reporter strain designed to detect autoinducer-2 (AI-2)-interfering activities (AI2-QQ.1) contained the E. coli ccdB lethal gene under the control of the E. coli lsrA promoter. The second reporter strain (AI1-QQ.1) contained the Vibrio fischeri luxI promoter fused to the ccdB gene to detect interference with acyl-homoserine lactones. Bacteria isolated from the surfaces of several marine eukarya were screened for quorum-quenching (QQ) activities using the established reporter systems AI1-QQ.1 and AI2-QQ.1. Out of 34 isolates, two interfered with acylated homoserine lactone (AHL) signaling, five interfered with AI-2 QS signaling, and 10 were demonstrated to interfere with both signal molecules. Open reading frames (ORFs) conferring QQ activity were identified for three selected isolates (Photobacterium sp., Pseudoalteromonas sp., and Vibrio parahaemolyticus). Evaluation of the respective heterologously expressed and purified QQ proteins confirmed their ability to interfere with the AHL and AI-2 signaling processes. Q uorum sensing (QS) is the cell-cell communication betweenbacteria that allows the perception of population density by small signaling molecules-so-called autoinducers-and modifies gene expression in response to the population density. It controls a wide spectrum of processes and phenotypic behaviors, including stress resistance, production of toxins and secondary metabolites, pathogenicity, swarming, and biofilm formation (for a review, see references 1 and 2). In addition to playing important roles in intraspecies and interspecies communication, QS is also involved in host-microbe interactions (3-5). Intraspecific communication of Gram-negative bacteria is based on the production and perception of acylated homoserine lactones (AHLs) synthesized by LuxI homologs. Increasing intracellular concentrations of diffusible AHLs with higher cell densities are perceived by binding of the AHLs to the cognate receptor (e.g., LuxR in Vibrio fischeri), resulting in activation or inhibition of target gene transcription (6, 7). Interspecific communication between different species within one habitat has been demonstrated to depend on the synthesis and detection of the universal autoinducer-2 (AI-2), which can be inhibited by furanones (8, 9). The perception of these signal molecules is achieved either by a two-component regulatory system (e.g., in Vibrio harveyi, where the induced phosphorylation cascade finally results in the induction of specific target genes) (10), or by transportation of the signal molecule into the cell (e.g., in Escherichia coli,...

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Section: Resultsmentioning

confidence: 99%

Novel Reporter for Identification of Interference with Acyl Homoserine Lactone and Autoinducer-2 Quorum Sensing

Weiland‐Bräuer

Pinnow

Schmitz

2015

Appl Environ Microbiol

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“…Both in vivo and in vitro, CcdA interacts with CcdB (50,52). This interaction prevents the cytotoxic activity of CcdB (30). A polypeptide called CcdA41, consisting of the 41 carboxy-terminal amino acids of CcdA, retains the ability to interact with CcdB and thus to prevent its cytotoxic activity (5).…”

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The Highly Conserved TldD and TldE Proteins of Escherichia coli Are Involved in Microcin B17 Processing and in CcdA Degradation

et al. 2002

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Microcin B17 (MccB17) is a peptide antibiotic produced by Escherichia coli strains carrying the pMccB17 plasmid. MccB17 is synthesized as a precursor containing an amino-terminal leader peptide that is cleaved during maturation. Maturation requires the product of the chromosomal tldE (pmbA) gene. Mature microcin is exported across the cytoplasmic membrane by a dedicated ABC transporter. In sensitive cells, MccB17 targets the essential topoisomerase II DNA gyrase. Independently, tldE as well as tldD mutants were isolated as being resistant to CcdB, another natural poison of gyrase encoded by the ccd poison-antidote system of plasmid F. This led to the idea that TldD and TldE could regulate gyrase function. We present in vivo evidence supporting the hypothesis that TldD and TldE have proteolytic activity. We show that in bacterial mutants devoid of either TldD or TldE activity, the MccB17 precursor accumulates and is not exported. Similarly, in the ccd system, we found that TldD and TldE are involved in CcdA and CcdA41 antidote degradation rather than being involved in the CcdB resistance mechanism. Interestingly, sequence database comparisons revealed that these two proteins have homologues in eubacteria and archaebacteria, suggesting a broader physiological role.

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“…The plasmid-encoded ccdA and ccdB genes are involved in the latter process (7)(8)(9)19). Interestingly enough, at least the ccdB gene product, the CcdB protein (Mr 11,700), also participates in F DNA replication initiated at origin V (13) (Fig.…”

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Control of the ccd operon in plasmid F

Tam

Kline

1989

J Bacteriol

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The F sex factor plasmid of Escherichia coli contains a pair of genes, ccdA and ccdB, whose protein gene products are involved in an unusual feature of plasmid maintenance. The CcdB protein is a cytotoxin that becomes activated when the F plasmid is lost, thereby killing the F-segregant cells. In F+ cells, the CcdA protein protects against the lethal effects of CcdB. In the present study we show that ccdA and ccdB expressions are negatively autoregulated at the level of transcription. Genetic studies showed that repression required at least ccdB; ccdA alone was without effect, and ccdB alone was not examined because it is lethal. Ccd-operator complexes were purified and contained a mixture of both CcdA and CcdB proteins; however, we could not conclude from our results whether CcdA was necessary for DNA binding or autorepression. By using restriction fragments of the promoter-operator region, we obtained results indicating that at least two DNA-binding sites existed for the Ccd protein(s). Subsequent footprinting of the binding sites showed protection over about a 113-base-pair region encompassing the putative promoter-operator and the beginning of the cedA gene.An F+ culture maintains its F plasmids not only by periodic plasmid replication and equipartitioning but also by destruction of F-segregants. The plasmid-encoded ccdA and ccdB genes are involved in the latter process (7-9, 19). Interestingly enough, at least the ccdB gene product, the CcdB protein (Mr 11,700), also participates in F DNA replication initiated at origin V (13) (Fig. 1).Very little is known about how the ccd proteins affect any of their functions. With respect to destruction of F-segregants, nascent F-cells grow and divide normally for two or three generations and then filament and lose their ability to act as colony-forming cells (7,8). The CcdB protein is necessary for filamentation and is lethal in the absence of CcdA protein (Mr 8,700), which implies that the latter neutralizes CcdB (19). CcdA and CcdB form a complex of about 69,000 Mr in vitro (Tam and Kline, submitted for publication). A comparable interaction in vivo could be relevant to neutralization of the lethal effects of CcdB.The ccd locus has been sequenced (20), and the proteins have been expressed and partially characterized by twodimensional gel electrophoresis (1). In these earlier publications, the proteins were referred to as H(CcdA) and G(CcdB), but we now refer to them according to the widely employed convention mimicking the name of the genetic locus. Both the sequence and expression data suggested that ccdA, ccdB, and the repD locus might form an operon. The latter locus encodes a site-specific resolvase (12).Our purpose in the present work has been to define control of ccd expression. Our results indicate that expression of ccdA and ccdB is negatively controlled at the level of transcription. At least the CcdB protein is required for repression, and perhaps CcdA is required as well. The CcdA protein by itself is not regulatory. We have cloned the ccdA and ccdB genes ...

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Ham22, a mini-F mutation which is lethal to host cell and promotes recA-dependent induction of lambdoid prophage.

Cited by 67 publications

References 26 publications

Novel Reporter for Identification of Interference with Acyl Homoserine Lactone and Autoinducer-2 Quorum Sensing

Novel Reporter for Identification of Interference with Acyl Homoserine Lactone and Autoinducer-2 Quorum Sensing

The Highly Conserved TldD and TldE Proteins of Escherichia coli Are Involved in Microcin B17 Processing and in CcdA Degradation

Control of the ccd operon in plasmid F

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