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Salmonella genomic island 1 (SGI1) reshapes the mating apparatus of IncC conjugative plasmids to promote self-propagation

IncC conjugative plasmids and Salmonella genomic island 1 (SGI1) and relatives are frequently associated with multidrug resistance of clinical isolates of pathogenic Enterobacteriaceae. SGI1 is specifically mobilized in trans by IncA and IncC plasmids (commonly referred to as A/C plasmids) following...

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Autores principales: Carraro, Nicolas, Durand, Romain, Rivard, Nicolas, Anquetil, Charley, Barrette, Catherine, Humbert, Malika, Burrus, Vincent
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5389848/
https://www.ncbi.nlm.nih.gov/pubmed/28355215
http://dx.doi.org/10.1371/journal.pgen.1006705
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author Carraro, Nicolas
Durand, Romain
Rivard, Nicolas
Anquetil, Charley
Barrette, Catherine
Humbert, Malika
Burrus, Vincent
author_facet Carraro, Nicolas
Durand, Romain
Rivard, Nicolas
Anquetil, Charley
Barrette, Catherine
Humbert, Malika
Burrus, Vincent
author_sort Carraro, Nicolas
collection PubMed
description IncC conjugative plasmids and Salmonella genomic island 1 (SGI1) and relatives are frequently associated with multidrug resistance of clinical isolates of pathogenic Enterobacteriaceae. SGI1 is specifically mobilized in trans by IncA and IncC plasmids (commonly referred to as A/C plasmids) following its excision from the chromosome, an event triggered by the transcriptional activator complex AcaCD encoded by these helper plasmids. Although SGI1 is not self-transmissible, it carries three genes, traN(S), traH(S) and traG(S), coding for distant homologs of the predicted mating pore subunits TraN(C), TraH(C) and TraG(C), respectively, encoded by A/C plasmids. Here we investigated the regulation of traN(S) and traHG(S) and the role of these three genes in the transmissibility of SGI1. Transcriptional fusion of the promoter sequences of traN(S) and traHG(S) to the reporter gene lacZ confirmed that expression of these genes is inducible by AcaCD. Mating experiments using combinations of deletion mutants of SGI1 and the helper IncC plasmid pVCR94 revealed complex interactions between these two mobile genetic elements. Whereas traN(C) and traHG(C) are essential for IncC plasmid transfer, SGI1 could rescue null mutants of each individual gene revealing that TraN(S), TraH(S) and TraG(S) are functional proteins. Complementation assays of individual tra(C) and tra(S) mutants showed that not only do TraN(S)/H(S)/G(S) replace TraN(C)/H(C)/G(C) in the mating pore encoded by IncC plasmids but also that traG(S) and traH(S) are both required for SGI1 optimal transfer. In fact, remodeling of the IncC-encoded mating pore by SGI1 was found to be essential to enhance transfer rate of SGI1 over the helper plasmid. Furthermore, traG(S) was found to be crucial to allow DNA transfer between cells bearing IncC helper plasmids, thereby suggesting that by remodeling the mating pore SGI1 disables an IncC-encoded entry exclusion mechanism. Hence tra(S) genes facilitate the invasion by SGI1 of cell populations bearing IncC plasmids.
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spelling pubmed-53898482017-05-03 Salmonella genomic island 1 (SGI1) reshapes the mating apparatus of IncC conjugative plasmids to promote self-propagation Carraro, Nicolas Durand, Romain Rivard, Nicolas Anquetil, Charley Barrette, Catherine Humbert, Malika Burrus, Vincent PLoS Genet Research Article IncC conjugative plasmids and Salmonella genomic island 1 (SGI1) and relatives are frequently associated with multidrug resistance of clinical isolates of pathogenic Enterobacteriaceae. SGI1 is specifically mobilized in trans by IncA and IncC plasmids (commonly referred to as A/C plasmids) following its excision from the chromosome, an event triggered by the transcriptional activator complex AcaCD encoded by these helper plasmids. Although SGI1 is not self-transmissible, it carries three genes, traN(S), traH(S) and traG(S), coding for distant homologs of the predicted mating pore subunits TraN(C), TraH(C) and TraG(C), respectively, encoded by A/C plasmids. Here we investigated the regulation of traN(S) and traHG(S) and the role of these three genes in the transmissibility of SGI1. Transcriptional fusion of the promoter sequences of traN(S) and traHG(S) to the reporter gene lacZ confirmed that expression of these genes is inducible by AcaCD. Mating experiments using combinations of deletion mutants of SGI1 and the helper IncC plasmid pVCR94 revealed complex interactions between these two mobile genetic elements. Whereas traN(C) and traHG(C) are essential for IncC plasmid transfer, SGI1 could rescue null mutants of each individual gene revealing that TraN(S), TraH(S) and TraG(S) are functional proteins. Complementation assays of individual tra(C) and tra(S) mutants showed that not only do TraN(S)/H(S)/G(S) replace TraN(C)/H(C)/G(C) in the mating pore encoded by IncC plasmids but also that traG(S) and traH(S) are both required for SGI1 optimal transfer. In fact, remodeling of the IncC-encoded mating pore by SGI1 was found to be essential to enhance transfer rate of SGI1 over the helper plasmid. Furthermore, traG(S) was found to be crucial to allow DNA transfer between cells bearing IncC helper plasmids, thereby suggesting that by remodeling the mating pore SGI1 disables an IncC-encoded entry exclusion mechanism. Hence tra(S) genes facilitate the invasion by SGI1 of cell populations bearing IncC plasmids. Public Library of Science 2017-03-29 /pmc/articles/PMC5389848/ /pubmed/28355215 http://dx.doi.org/10.1371/journal.pgen.1006705 Text en © 2017 Carraro et al http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
spellingShingle Research Article
Carraro, Nicolas
Durand, Romain
Rivard, Nicolas
Anquetil, Charley
Barrette, Catherine
Humbert, Malika
Burrus, Vincent
Salmonella genomic island 1 (SGI1) reshapes the mating apparatus of IncC conjugative plasmids to promote self-propagation
title Salmonella genomic island 1 (SGI1) reshapes the mating apparatus of IncC conjugative plasmids to promote self-propagation
title_full Salmonella genomic island 1 (SGI1) reshapes the mating apparatus of IncC conjugative plasmids to promote self-propagation
title_fullStr Salmonella genomic island 1 (SGI1) reshapes the mating apparatus of IncC conjugative plasmids to promote self-propagation
title_full_unstemmed Salmonella genomic island 1 (SGI1) reshapes the mating apparatus of IncC conjugative plasmids to promote self-propagation
title_short Salmonella genomic island 1 (SGI1) reshapes the mating apparatus of IncC conjugative plasmids to promote self-propagation
title_sort salmonella genomic island 1 (sgi1) reshapes the mating apparatus of incc conjugative plasmids to promote self-propagation
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5389848/
https://www.ncbi.nlm.nih.gov/pubmed/28355215
http://dx.doi.org/10.1371/journal.pgen.1006705
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