Evolution of compatible replicons of the related IncQ-like plasmids, pTC-F14 and pTF-FC2

Gardner, Murray N.; Rawlings, Douglas E.

doi:10.1099/mic.0.26951-0

Cited by 9 publications

(5 citation statements)

References 28 publications

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“…However, replicon diversity is naturally limited by strong functional constraints. Even closely evolutionarily related compatible plasmids with cross-complementing primases and helicases have highly specific oriV -Rep DNA binding requirements [ 60 ]. Even if target plasmids develop oriV mutations so that they are no longer incompatible and can then co-inhabit a cell with the interference plasmid, these plasmids are still expected to be rendered relatively unstable by specific antitoxin excess.…”

Section: Discussionmentioning

confidence: 99%

Plasmid interference for curing antibiotic resistance plasmids in vivo

et al. 2017

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Antibiotic resistance increases the likelihood of death from infection by common pathogens such as Escherichia coli and Klebsiella pneumoniae in developed and developing countries alike. Most important modern antibiotic resistance genes spread between such species on self-transmissible (conjugative) plasmids. These plasmids are traditionally grouped on the basis of replicon incompatibility (Inc), which prevents coexistence of related plasmids in the same cell. These plasmids also use post-segregational killing (‘addiction’) systems, which poison any bacterial cells that lose the addictive plasmid, to guarantee their own survival. This study demonstrates that plasmid incompatibilities and addiction systems can be exploited to achieve the safe and complete eradication of antibiotic resistance from bacteria in vitro and in the mouse gut. Conjugative ‘interference plasmids’ were constructed by specifically deleting toxin and antibiotic resistance genes from target plasmids. These interference plasmids efficiently cured the corresponding antibiotic resistant target plasmid from different Enterobacteriaceae in vitro and restored antibiotic susceptibility in vivo to all bacterial populations into which plasmid-mediated resistance had spread. This approach might allow eradication of emergent or established populations of resistance plasmids in individuals at risk of severe sepsis, enabling subsequent use of less toxic and/or more effective antibiotics than would otherwise be possible, if sepsis develops. The generalisability of this approach and its potential applications in bioremediation of animal and environmental microbiomes should now be systematically explored.

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Section: Discussionmentioning

confidence: 99%

Plasmid interference for curing antibiotic resistance plasmids in vivo

et al. 2017

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“…The additional 6-bp repeat resulted in an increase in expression of the mobB-mobA/repB operon and it was the increase in expression of the RepB primase that resulted in a higher plasmid copy number. The altered promoter could either increase the efficiency of initiation of mobBmobA/repB transcription or decrease autorepression by RepB (14). Swapping the region with the repeats between pRAS3.1 and pRAS3.2 resulted in a corresponding change in copy number.…”

Section: Discussionmentioning

confidence: 99%

Comparative Biology of Two Natural Variants of the IncQ-2 Family Plasmids, pRAS3.1 and pRAS3.2

Loftie-Eaton

Rawlings

2009

J Bacteriol

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Plasmids pRAS3.1 and pRAS3.2 are two closely related, natural variants of the IncQ-2 plasmid family that have identical plasmid backbones except for two differences. Plasmid pRAS3.1 has five 6-bp repeat sequences in the promoter region of the mobB gene and four 22-bp iterons in its oriV region, whereas pRAS3.2 has only four 6-bp repeats and three 22-bp iterons. Plasmid pRAS3.1 was found to have a higher copy number than pRAS3.2, and we show that the extra 6-bp repeat results in an increase in mobB and downstream mobA/repB expression. Placement of repB (primase) behind an arabinose-inducible promoter in trans resulted in an increase in repB expression and an approximately twofold increase in the copy number of plasmids with identical numbers of 22-bp iterons. The pRAS3 plasmids were shown to have a previously unrecognized toxin-antitoxin plasmid stability module within their replicons. The ability of the pRAS3 plasmids to mobilize the oriT regions of two other plasmids of the IncQ-2 family, pTF-FC2 and pTC-F14, suggested that the mobilization proteins pRAS3 are relaxed and can mobilize oriT regions with substantially different sequences. Plasmids pRAS3.1 and pRAS3.2 were highly incompatible with plasmids pTF-FC2 and pTC-F14, and this incompatibility was removed on inactivation of an open reading frame situated downstream of the mobCDE mobilization genes rather than being due to the 22-bp oriV-associated iterons. We propose that the pRAS3 plasmids represent a third, ␥ incompatibility group within the IncQ-2 family plasmids.Plasmids of the IncQ family are small (Ͻ20 kb), have a broad host range, and are highly promiscuous due to their ability to be mobilized very efficiently by self-transmissible plasmids such as the IncP plasmids. They have been divided into two families, IncQ-1 and IncQ-2, based on the amino acid sequence relatedness of their RepA (helicase), RepB (primase), and RepC (DNA-binding) replication proteins and because the mobilization proteins of the two families are unrelated, consisting of three or five genes, respectively (31). IncQ-1 group plasmids include RSF1010 and the near-identical R1162, pDN1, pIE1107, pIE1115, and pIE1130, while IncQ-2 plasmids include pTF-FC2, pTC-F14, and pRAS3.IncQ-2 plasmids pRAS3.1 and pRAS3.2 were isolated in Norway from the fish pathogens Aeromonas salmonicida subsp. salmonicida and atypical A. salmonicida, respectively, while investigating plasmids that conferred resistance to tetracycline (21). The two plasmids encode identical replication and mobilization proteins, with the most important differences in the plasmid backbone being that pRAS3.1 has four 22-bp iterons in its oriV region and five 6-bp repeat sequences upstream of its mobB gene, whereas pRAS3.2 has only three iterons and four 6-bp repeat sequences. No biological studies were carried out in the initial report of the pRAS3 plasmids. As a contribution to our studies on the evolution of IncQ plasmids, our longerterm aim is to address the question of why two natural versions of the plasmid exist. Here we re...

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“…Plasmids pTF-FC2 (IncQ-2a) and pTC-F14 (IncQ-2b) share with other IncQ-family replicons the presence of repB, repA and repC genes encoding the primase, helicase and iteron-binding protein, respectively (Dorrington and Rawlings, 1990;Rohrer and Rawlings, 1992), as well as a 22-bp iteron based oriV (Rawlings and Tietze, 2001). Despite their similarity, their origins of replication are compatible (Gardner et al, 2004). Both plasmids lack an active partitioning system and their stability depends on the toxin-antitoxin system PasAB, which also seem to play a role in copy number control (Matcher and Rawlings, 2009;Deane and Rawlings, 2004;Gardner et al, 2001), resembling CopG-mediated control of crenarchaeal pRN1-family plasmids.…”

Section: ! 242mentioning

confidence: 99%

The Flexible Genome of Acidophilic Prokaryotes

Beard¹,

Ossandon²,

Rawlings³

et al. 2021

Current Issues in Molecular Biology

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Over the last couple of decades there has been considerable progress in the identification and understanding of the mobile genetic elements that are exchanged between microbes in extremely acidic environments, and of the genes piggybacking on them. Numerous plasmid families, unique viruses of bizarre morphologies and lyfe cycles, as well as plasmid-virus chimeras, have been isolated from acidophiles and characterized to varying degrees. Growing evidence provided by omic-studies have shown that the mobile elements repertoire is not restricted to plasmids and viruses, but that a plethora of integrative elements ranging from miniature inverted repeat transposable elements to large integrative conjugative elements populate the genomes of acidophilic bacteria and archaea. This article reviews the diversity of elements that have been found to constitute the flexible genome of acidophiles. Special emphasis is put on the knowledge generated for Sulfolobus (archaea) and species of the bacterial genera Acidithiobacillus and Leptospirillum. Also, recent knowledge on the strategies used by acidophiles to contain deletereous exchanges while allowing innovation, and the emerging details of the molecular biology of these systems, are discussed. Major lacunae in our understanding of the mobilome of acidophilic prokaryotes and topics for further investigations are identified.

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Evolution of compatible replicons of the related IncQ-like plasmids, pTC-F14 and pTF-FC2

Cited by 9 publications

References 28 publications

Plasmid interference for curing antibiotic resistance plasmids in vivo

Plasmid interference for curing antibiotic resistance plasmids in vivo

Comparative Biology of Two Natural Variants of the IncQ-2 Family Plasmids, pRAS3.1 and pRAS3.2

The Flexible Genome of Acidophilic Prokaryotes

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