The Plasmid Status of Satellite Bacteriophage P4

Briani, Federica; Dehò, Gianni; Forti, Francesca; Ghisotti, Daniela

doi:10.1006/plas.2000.1497

Cited by 72 publications

(59 citation statements)

References 93 publications

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“…Substantial analogies can be found between the transpovirons and virus-associated plasmids present in bacteria and archaea. In particular, the well-studied bacteriophage P4 (also known as a "phasmid") is a plasmid that replicates episomally in the absence of the helper bacteriophage P2 but is encapsidated into virions and thus can infect new bacterial cells in the presence of the helper (31,32). A similar replication strategy has been described for the archaeal virus plasmid pSSVx that depends on the fuselloviruses SSV1 or SSV2 and appears to have acquired genes from a fusellovirus (33).…”

Section: Discussionmentioning

confidence: 99%

Provirophages and transpovirons as the diverse mobilome of giant viruses

Desnues

Scola

Yutin

et al. 2012

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

191

232

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A distinct class of infectious agents, the virophages that infect giant viruses of the Mimiviridae family, has been recently described. Here we report the simultaneous discovery of a giant virus of Acanthamoeba polyphaga (Lentille virus) that contains an integrated genome of a virophage (Sputnik 2), and a member of a previously unknown class of mobile genetic elements, the transpovirons. The transpovirons are linear DNA elements of ∼7 kb that encompass six to eight protein-coding genes, two of which are homologous to virophage genes. Fluorescence in situ hybridization showed that the free form of the transpoviron replicates within the giant virus factory and accumulates in high copy numbers inside giant virus particles, Sputnik 2 particles, and amoeba cytoplasm. Analysis of deep-sequencing data showed that the virophage and the transpoviron can integrate in nearly any place in the chromosome of the giant virus host and that, although less frequently, the transpoviron can also be linked to the virophage chromosome. In addition, integrated fragments of transpoviron DNA were detected in several giant virus and Sputnik genomes. Analysis of 19 Mimivirus strains revealed three distinct transpovirons associated with three subgroups of Mimiviruses. The virophage, the transpoviron, and the previously identified self-splicing introns and inteins constitute the complex, interconnected mobilome of the giant viruses and are likely to substantially contribute to interviral gene transfer.

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Section: Discussionmentioning

confidence: 99%

Provirophages and transpovirons as the diverse mobilome of giant viruses

Desnues

Scola

Yutin

et al. 2012

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

191

232

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“…However, so far there have been no data to support the interaction between Kid (PemK) and DnaB. It is interesting to note that the ColE1 replication is initiated by RNA II and inhibited by RNA I (39,40), whereas the P4 DNA replication is mainly regulated by ␣ protein (41). RNases involved in the metabolism of RNA I and RNA II are expected to play a key role in the control of the ColE1 plasmid replication (42).…”

Section: Discussionmentioning

confidence: 99%

Interference of mRNA Function by Sequence-specific Endoribonuclease PemK

Zhang

Zhu

et al. 2004

Journal of Biological Chemistry

122

149

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In Escherichia coli, programmed cell death is mediated through the system called "addiction module," which consists of a pair of genes encoding a stable toxin and a labile antitoxin. The pemI-pemK system is an addiction module present on plasmid R100. It helps to maintain the plasmid by post-segregational killing in E. coli population. Here we demonstrate that purified PemK, the toxin encoded by the pemI-pemK addiction module, inhibits protein synthesis in an E. coli cell-free system, whereas the addition of PemI, the antitoxin against PemK, resumes the protein synthesis. Further studies reveal that PemK is a sequence-specific endoribonuclease that cleaves mRNAs to inhibit protein synthesis, whereas PemI blocks the endoribonuclease activity of PemK. PemK cleaves only single-stranded RNA preferentially at the 5 or 3 side of the A residue in the "UAH" sequences (where H is C, A, or U). Upon induction, PemK cleaves cellular mRNAs to effectively block protein synthesis in E. coli. The pemK homologue genes have been identified on the genomes of a wide range of bacteria. We propose that PemK and its homologues form a novel endoribonuclease family that interferes with mRNA function by cleaving cellular mRNAs in a sequence-specific manner.In Escherichia coli, programmed cell death is proposed to be mediated through the system called "addiction module," which consists of a pair of genes encoding a toxin and an antitoxin (1). The addiction module has the following properties. (a) The toxic protein is stable, whereas the antitoxin is a labile protein. (b) The toxin and the antitoxin are coexpressed from an operon and interact with each other to form a stable complex. (c) Their expression is auto-regulated either by the toxin-antitoxin complex or by the antitoxin alone. When the co-expression is inhibited under stress conditions, the antitoxin is degraded by proteases, enabling the toxin to act on its target. In E. coli, some extrachromosomal elements are known to contain addiction modules causing the bacterial programmed cell death by the so-called postsegregational killing effect. The most studied extrachromosomal addiction modules are the phd-doc system on bacteriophage P1 (2-5), the ccdA-ccdB system on factor F (6 -9), the kis-kid system on plasmid R1 (10 -13), and the pemIpemK system on plasmid R100 (14 -17). Interestingly, the E. coli chromosome also contains several addiction module systems, such as the relBE system (18 -21), the mazEF system (22-25), and the chpB system (26 -28).The cellular effects of the toxins in the addiction modules have been studied quite extensively. CcdB, the toxin in the ccdA-ccdB system, interacts with DNA gyrase to block DNA replication (7,29), and RelE, the toxin in the relBE system, is not able to degrade free RNA but cleaves mRNA in the ribosome A site with high codon specificity (21). Recently, it was demonstrated that the A-site mRNA cleavage can occur in the absence of RelE (30). The exact mechanism of the A-site mRNA cleavage is still unknown. It has been proposed that MazF (ChpAK)...

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“…Detection of circularized ST46 DNA supports a continuing role for P4 phage in genome diversification at the tRNA leuX locus. The detection of circularized ST46 DNA would suggest that this phage can be mobilized from the lysogenic state and would support a continuing role for P4 phages in genome diversification at the tRNA leuX locus (14). To investigate this possibility, PCR was used to detect circularized ST46 released by Salmonella serovar Typhi BRD948.…”

Section: Downloaded Frommentioning

confidence: 99%

Analysis of the Hypervariable Region of the Salmonella enterica Genome Associated with tRNA ^leuX

et al. 2005

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The divergence of Salmonella enterica and Escherichia coli is estimated to have occurred approximately 140 million years ago. Despite this evolutionary distance, the genomes of these two species still share extensive synteny and homology. However, there are significant differences between the two species in terms of genes putatively acquired via various horizontal transfer events. Here we report on the composition and distribution across the Salmonella genus of a chromosomal region designated SPI-10 in Salmonella enterica serovar Typhi and located adjacent to tRNA leuX . We find that across the Salmonella genus the tRNA leuX region is a hypervariable hot spot for horizontal gene transfer; different isolates from the same S. enterica serovar can exhibit significant variation in this region. Many P4 phage, plasmid, and transposable element-associated genes are found adjacent to tRNA leuX in both Salmonella and E. coli, suggesting that these mobile genetic elements have played a major role in driving the variability of this region.

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The Plasmid Status of Satellite Bacteriophage P4

Cited by 72 publications

References 93 publications

Provirophages and transpovirons as the diverse mobilome of giant viruses

Provirophages and transpovirons as the diverse mobilome of giant viruses

Interference of mRNA Function by Sequence-specific Endoribonuclease PemK

Analysis of the Hypervariable Region of the Salmonella enterica Genome Associated with tRNA ^leuX

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The Plasmid Status of Satellite Bacteriophage P4

Cited by 72 publications

References 93 publications

Provirophages and transpovirons as the diverse mobilome of giant viruses

Provirophages and transpovirons as the diverse mobilome of giant viruses

Interference of mRNA Function by Sequence-specific Endoribonuclease PemK

Analysis of the Hypervariable Region of the Salmonella enterica Genome Associated with tRNA leuX

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Analysis of the Hypervariable Region of the Salmonella enterica Genome Associated with tRNA ^leuX