Actinomycete integrative and conjugative elements

Poele, Evelien M. te; Bolhuis, Henk; Dijkhuizen, Lubbert

doi:10.1007/s10482-008-9255-x

Cited by 59 publications

(74 citation statements)

References 73 publications

(113 reference statements)

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“…The second set of conjugative elements, originally termed "conjugative transposons" and more recently termed "integrative and conjugative elements" (ICEs), are also present in many bacterial and archaeal species (40,41,150,151,152,240,260). These elements are processed for translocation first by excision from the chromosome through the action of a recombinase/excisionase complex and by the formation of a circular intermediate (Fig.…”

Section: Conjugation Systemsmentioning

confidence: 99%

“…In the gram-positive Actinomycetes, some conjugative plasmids and ICEs are translocated from mycelial donor to recipient cells as dsDNA transfer intermediates (116,216,260). These elements code for an unusual T4CP, which is capable of recognizing and translocating dsDNA substrates independently of other Mpf channel subunits.…”

Section: Novel Conjugative Dna Transfer Processing Reactionsmentioning

confidence: 99%

“…This protein is phylogenetically related to B. subtilis SpoIIIE and E. coli FtsK, which mediate the translocation of chromosomal DNA across septal membranes during B. subtilis sporulation and E. coli cell division, respectively (30,187). Not surprisingly, the Actinomycetes ICEs or integrated plasmids can also function as Hfr-like elements and mediate the transfer of large segments of chromosomal DNA across mycelial membranes (116,260).…”

Section: Novel Conjugative Dna Transfer Processing Reactionsmentioning

confidence: 99%

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Biological Diversity of Prokaryotic Type IV Secretion Systems

Martı́nez

Christie

2009

Microbiol Mol Biol Rev

623

780

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SUMMARY Type IV secretion systems (T4SS) translocate DNA and protein substrates across prokaryotic cell envelopes generally by a mechanism requiring direct contact with a target cell. Three types of T4SS have been described: (i) conjugation systems, operationally defined as machines that translocate DNA substrates intercellularly by a contact-dependent process; (ii) effector translocator systems, functioning to deliver proteins or other macromolecules to eukaryotic target cells; and (iii) DNA release/uptake systems, which translocate DNA to or from the extracellular milieu. Studies of a few paradigmatic systems, notably the conjugation systems of plasmids F, R388, RP4, and pKM101 and the Agrobacterium tumefaciens VirB/VirD4 system, have supplied important insights into the structure, function, and mechanism of action of type IV secretion machines. Information on these systems is updated, with emphasis on recent exciting structural advances. An underappreciated feature of T4SS, most notably of the conjugation subfamily, is that they are widely distributed among many species of gram-negative and -positive bacteria, wall-less bacteria, and the Archaea. Conjugation-mediated lateral gene transfer has shaped the genomes of most if not all prokaryotes over evolutionary time and also contributed in the short term to the dissemination of antibiotic resistance and other virulence traits among medically important pathogens. How have these machines adapted to function across envelopes of distantly related microorganisms? A survey of T4SS functioning in phylogenetically diverse species highlights the biological complexity of these translocation systems and identifies common mechanistic themes as well as novel adaptations for specialized purposes relating to the modulation of the donor-target cell interaction.

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Section: Conjugation Systemsmentioning

confidence: 99%

Section: Novel Conjugative Dna Transfer Processing Reactionsmentioning

confidence: 99%

Section: Novel Conjugative Dna Transfer Processing Reactionsmentioning

confidence: 99%

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Biological Diversity of Prokaryotic Type IV Secretion Systems

Martı́nez

Christie

2009

Microbiol Mol Biol Rev

623

780

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“…Analysis of the Glutamicibacter JB182 RUSTI region revealed homologs of each of these protein classes ( Figure 3A): a recombinase of the site-specific tyrosine recombinase XerD family (Ga0099663_102762) (Subramanya et al, 1997), a hexameric ATPase conjugation protein of the VirD4/TraG/TraD family (Ga0099663_102784) (Hamilton et al, 2000), and a homolog of the bi-functional primase-polymerase DNA replication protein family (Ga0099663_102766). Interestingly, Actinobacterial ICE systems typically use conjugation apparatus belonging to the SpoIIE/FtsK family, which allows transfer of double-stranded DNA (te Poele et al, 2008;Bordeleau et al, 2012). However, the conjugation machinery here is more reminiscent of gram-negative and Firmicute systems of single-stranded transfer (Burrus and Waldor, 2004).…”

Section: Iron Acquisition Hgtmentioning

confidence: 99%

Extensive Horizontal Gene Transfer in Cheese-Associated Bacteria

Bonham

Wolfe

Dutton

2016

Preprint

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Acquisition of genes through horizontal gene transfer (HGT) allows microbes to rapidly gain new capabilities and adapt to new or changing environments. Identifying widespread HGT regions within multispecies microbiomes can pinpoint the molecular mechanisms that play key roles in microbiome assembly. We sought to identify horizontally transferred genes within a model microbiome, the cheese rind. Comparing 31 newly sequenced and 134 previously sequenced bacterial isolates from cheese rinds, we identified over 200 putative horizontally transferred genomic regions containing 4733 protein coding genes. The largest of these regions are enriched for genes involved in siderophore acquisition, and are widely distributed in cheese rinds in both Europe and the US. These results suggest that HGT is prevalent in cheese rind microbiomes, and that identification of genes that are frequently transferred in a particular environment may provide insight into the selective forces shaping microbial communities.

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“…A site-specific recombinase (integrase) catalyzes this excision and the formation of a circular plasmid species that is a substrate for conjugative transfer. All functional ICEs that use a type IV secretion system (i.e., ICEs in organisms other than actinomycetes [7]) contain an origin of transfer oriT and encode a cognate relaxase. The relaxase nicks at a site in the oriT and becomes covalently attached to the 5= end of the DNA.…”

mentioning

confidence: 99%

Autonomous Replication of the Conjugative Transposon Tn916

2016

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Integrative and conjugative elements (ICEs), also known as conjugative transposons, are self-transferable elements that are widely distributed among bacterial phyla and are important drivers of horizontal gene transfer. Many ICEs carry genes that confer antibiotic resistances to their host cells and are involved in the dissemination of these resistance genes. ICEs reside in host chromosomes but under certain conditions can excise to form a plasmid that is typically the substrate for transfer. A few ICEs are known to undergo autonomous replication following activation. However, it is not clear if autonomous replication is a general property of many ICEs. We found that Tn916, the first conjugative transposon identified, replicates autonomously via a rolling-circle mechanism. Replication of Tn916 was dependent on the relaxase encoded by orf20 of Tn916. The origin of transfer of Tn916, oriT(916), also functioned as an origin of replication. Using immunoprecipitation and mass spectrometry, we found that the relaxase (Orf20) and the two putative helicase processivity factors (Orf22 and Orf23) encoded by Tn916 likely interact in a complex and that the Tn916 relaxase contains a previously unidentified conserved helix-turn-helix domain in its N-terminal region that is required for relaxase function and replication. Lastly, we identified a functional single-strand origin of replication (sso) in Tn916 that we predict primes second-strand synthesis during rolling-circle replication. Together these results add to the emerging data that show that several ICEs replicate via a conserved, rolling-circle mechanism. IMPORTANCE Integrative and conjugative elements (ICEs) drive horizontal gene transfer and the spread of antibiotic resistances in bacteria.ICEs reside integrated in a host genome but can excise to create a plasmid that is the substrate for transfer to other cells. Here we show that Tn916, an ICE with broad host range, undergoes autonomous rolling-circle replication when in the plasmid form. We found that the origin of transfer functions as a double-stranded origin of replication and identified a single-stranded origin of replication. It was long thought that ICEs do not undergo autonomous replication. Our work adds to the evidence that ICEs replicate autonomously as part of their normal life cycle and indicates that diverse ICEs use the same replicative mechanism. Integrative and conjugative elements (ICEs), also called conjugative transposons, are mobile genetic elements that encode proteins that mediate transfer of the element from the host cell (donor) to a recipient by conjugation. ICEs often contain additional (cargo) genes that can provide a selective advantage to the host cells (reviewed in references 1 and 2). Most ICEs have been identified based on their cargo genes and the phenotypes conferred. For example, many ICEs carry genes encoding antibiotic resistances. The horizontal dissemination of ICEs and their associated cargo genes is a major driver of bacterial genome plasticity and evolution and the s...

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Actinomycete integrative and conjugative elements

Cited by 59 publications

References 73 publications

Biological Diversity of Prokaryotic Type IV Secretion Systems

Biological Diversity of Prokaryotic Type IV Secretion Systems

Extensive Horizontal Gene Transfer in Cheese-Associated Bacteria

Autonomous Replication of the Conjugative Transposon Tn916

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