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The extended regulatory networks of SXT/R391 integrative and conjugative elements and IncA/C conjugative plasmids.

Poulin-Laprade D, Carraro N, Burrus V - Front Microbiol (2015)

Bottom Line: Recently, the transcriptional regulators that govern their dissemination through the expression of ICE- or plasmid-encoded transfer genes have been described.Unrelated repressors control the activation of conjugation by preventing the expression of two related master activator complexes in both types of elements, i.e., SetCD in SXT/R391 ICEs and AcaCD in IncA/C plasmids.Finally, in addition to activating ICE- or plasmid-borne genes, these master activators have been shown to specifically activate phylogenetically unrelated mobilizable genomic islands (MGIs) that also disseminate antibiotic resistance genes and other adaptive traits among a plethora of pathogens such as Vibrio cholerae and Salmonella enterica.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Bacterial Molecular Genetics, Département de Biologie, Faculté des Sciences, Université de Sherbrooke , Sherbrooke, QC, Canada.

ABSTRACT
Nowadays, healthcare systems are challenged by a major worldwide drug resistance crisis caused by the massive and rapid dissemination of antibiotic resistance genes and associated emergence of multidrug resistant pathogenic bacteria, in both clinical and environmental settings. Conjugation is the main driving force of gene transfer among microorganisms. This mechanism of horizontal gene transfer mediates the translocation of large DNA fragments between two bacterial cells in direct contact. Integrative and conjugative elements (ICEs) of the SXT/R391 family (SRIs) and IncA/C conjugative plasmids (ACPs) are responsible for the dissemination of a broad spectrum of antibiotic resistance genes among diverse species of Enterobacteriaceae and Vibrionaceae. The biology, diversity, prevalence and distribution of these two families of conjugative elements have been the subject of extensive studies for the past 15 years. Recently, the transcriptional regulators that govern their dissemination through the expression of ICE- or plasmid-encoded transfer genes have been described. Unrelated repressors control the activation of conjugation by preventing the expression of two related master activator complexes in both types of elements, i.e., SetCD in SXT/R391 ICEs and AcaCD in IncA/C plasmids. Finally, in addition to activating ICE- or plasmid-borne genes, these master activators have been shown to specifically activate phylogenetically unrelated mobilizable genomic islands (MGIs) that also disseminate antibiotic resistance genes and other adaptive traits among a plethora of pathogens such as Vibrio cholerae and Salmonella enterica.

No MeSH data available.


Related in: MedlinePlus

Schematic representation of the genetic organization and transcriptional units of the conserved core of SXT/R391 ICEs (integrated in prfC) and pVCR94ΔX (circular map linearized at the start position of gene mobI) adapted from Poulin-Laprade et al. (2015) and Carraro et al. (2014a, 2015a). Genes are represented by arrows and color coded according to their function as indicated in the legend. For clarity, ORF names vcrxXXX were shortened as XXX for pVCR94ΔX. SetCD- and AcaCD-binding motifs located on positive and negative DNA strands are represented by light green and red narrow boxes, respectively. Operons are indicated by arrows positioned above represented genes. SetCD- and AcaCD-regulated promoters and operons are colored in green. Open circles mark operons interruptions generated by the map format. mob1-2, DNA processing; rep, replication; unk1-11, unknown; mpf1-3, mating pore formation; rec, recombination; reg1-2, regulation. P021–as and P140–as: vcrx021 and vcrx140 antisens promoters, respectively. P027–in: vcrx027 internal promoter. Black triangles show the position of variable cargo DNA in SRIs, while variable DNA regions inserted in the conserved core of ACPs are indicated below genes (VR1 to VR8). The origin of replication (oriV) and the origin of transfer (oriT) are indicated. The position of the FRT site resulting from the deletion of the antibiotic resistance gene cluster in pVCR94 is also shown.
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Figure 1: Schematic representation of the genetic organization and transcriptional units of the conserved core of SXT/R391 ICEs (integrated in prfC) and pVCR94ΔX (circular map linearized at the start position of gene mobI) adapted from Poulin-Laprade et al. (2015) and Carraro et al. (2014a, 2015a). Genes are represented by arrows and color coded according to their function as indicated in the legend. For clarity, ORF names vcrxXXX were shortened as XXX for pVCR94ΔX. SetCD- and AcaCD-binding motifs located on positive and negative DNA strands are represented by light green and red narrow boxes, respectively. Operons are indicated by arrows positioned above represented genes. SetCD- and AcaCD-regulated promoters and operons are colored in green. Open circles mark operons interruptions generated by the map format. mob1-2, DNA processing; rep, replication; unk1-11, unknown; mpf1-3, mating pore formation; rec, recombination; reg1-2, regulation. P021–as and P140–as: vcrx021 and vcrx140 antisens promoters, respectively. P027–in: vcrx027 internal promoter. Black triangles show the position of variable cargo DNA in SRIs, while variable DNA regions inserted in the conserved core of ACPs are indicated below genes (VR1 to VR8). The origin of replication (oriV) and the origin of transfer (oriT) are indicated. The position of the FRT site resulting from the deletion of the antibiotic resistance gene cluster in pVCR94 is also shown.

Mentions: All SRIs share 47 kb of DNA corresponding to a highly conserved core set of 52 genes with over 95% identity at the nucleotide level (Wozniak et al., 2009). About half of these genes have been shown to be essential to ensure the basic maintenance, transfer and regulatory functions of SRIs. These essential genes are clustered in four main modules (Figure 1), i.e., the int module which codes for the integrase and excisionase and ensures intracellular mobility, the mob and mpf modules which code for a type IV secretion system (T4SS) and is responsible of the intercellular mobility (DNA processing and mating pore formation), and the reg module coding for the regulatory network governing the expression of the other modules. Each module can contain one to several transcriptional unit(s) (Figure 1; Poulin-Laprade et al., 2015). The reg module of SRIs is the most highly conserved locus amongst members of this family of ICEs (Wozniak et al., 2009).


The extended regulatory networks of SXT/R391 integrative and conjugative elements and IncA/C conjugative plasmids.

Poulin-Laprade D, Carraro N, Burrus V - Front Microbiol (2015)

Schematic representation of the genetic organization and transcriptional units of the conserved core of SXT/R391 ICEs (integrated in prfC) and pVCR94ΔX (circular map linearized at the start position of gene mobI) adapted from Poulin-Laprade et al. (2015) and Carraro et al. (2014a, 2015a). Genes are represented by arrows and color coded according to their function as indicated in the legend. For clarity, ORF names vcrxXXX were shortened as XXX for pVCR94ΔX. SetCD- and AcaCD-binding motifs located on positive and negative DNA strands are represented by light green and red narrow boxes, respectively. Operons are indicated by arrows positioned above represented genes. SetCD- and AcaCD-regulated promoters and operons are colored in green. Open circles mark operons interruptions generated by the map format. mob1-2, DNA processing; rep, replication; unk1-11, unknown; mpf1-3, mating pore formation; rec, recombination; reg1-2, regulation. P021–as and P140–as: vcrx021 and vcrx140 antisens promoters, respectively. P027–in: vcrx027 internal promoter. Black triangles show the position of variable cargo DNA in SRIs, while variable DNA regions inserted in the conserved core of ACPs are indicated below genes (VR1 to VR8). The origin of replication (oriV) and the origin of transfer (oriT) are indicated. The position of the FRT site resulting from the deletion of the antibiotic resistance gene cluster in pVCR94 is also shown.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4542580&req=5

Figure 1: Schematic representation of the genetic organization and transcriptional units of the conserved core of SXT/R391 ICEs (integrated in prfC) and pVCR94ΔX (circular map linearized at the start position of gene mobI) adapted from Poulin-Laprade et al. (2015) and Carraro et al. (2014a, 2015a). Genes are represented by arrows and color coded according to their function as indicated in the legend. For clarity, ORF names vcrxXXX were shortened as XXX for pVCR94ΔX. SetCD- and AcaCD-binding motifs located on positive and negative DNA strands are represented by light green and red narrow boxes, respectively. Operons are indicated by arrows positioned above represented genes. SetCD- and AcaCD-regulated promoters and operons are colored in green. Open circles mark operons interruptions generated by the map format. mob1-2, DNA processing; rep, replication; unk1-11, unknown; mpf1-3, mating pore formation; rec, recombination; reg1-2, regulation. P021–as and P140–as: vcrx021 and vcrx140 antisens promoters, respectively. P027–in: vcrx027 internal promoter. Black triangles show the position of variable cargo DNA in SRIs, while variable DNA regions inserted in the conserved core of ACPs are indicated below genes (VR1 to VR8). The origin of replication (oriV) and the origin of transfer (oriT) are indicated. The position of the FRT site resulting from the deletion of the antibiotic resistance gene cluster in pVCR94 is also shown.
Mentions: All SRIs share 47 kb of DNA corresponding to a highly conserved core set of 52 genes with over 95% identity at the nucleotide level (Wozniak et al., 2009). About half of these genes have been shown to be essential to ensure the basic maintenance, transfer and regulatory functions of SRIs. These essential genes are clustered in four main modules (Figure 1), i.e., the int module which codes for the integrase and excisionase and ensures intracellular mobility, the mob and mpf modules which code for a type IV secretion system (T4SS) and is responsible of the intercellular mobility (DNA processing and mating pore formation), and the reg module coding for the regulatory network governing the expression of the other modules. Each module can contain one to several transcriptional unit(s) (Figure 1; Poulin-Laprade et al., 2015). The reg module of SRIs is the most highly conserved locus amongst members of this family of ICEs (Wozniak et al., 2009).

Bottom Line: Recently, the transcriptional regulators that govern their dissemination through the expression of ICE- or plasmid-encoded transfer genes have been described.Unrelated repressors control the activation of conjugation by preventing the expression of two related master activator complexes in both types of elements, i.e., SetCD in SXT/R391 ICEs and AcaCD in IncA/C plasmids.Finally, in addition to activating ICE- or plasmid-borne genes, these master activators have been shown to specifically activate phylogenetically unrelated mobilizable genomic islands (MGIs) that also disseminate antibiotic resistance genes and other adaptive traits among a plethora of pathogens such as Vibrio cholerae and Salmonella enterica.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Bacterial Molecular Genetics, Département de Biologie, Faculté des Sciences, Université de Sherbrooke , Sherbrooke, QC, Canada.

ABSTRACT
Nowadays, healthcare systems are challenged by a major worldwide drug resistance crisis caused by the massive and rapid dissemination of antibiotic resistance genes and associated emergence of multidrug resistant pathogenic bacteria, in both clinical and environmental settings. Conjugation is the main driving force of gene transfer among microorganisms. This mechanism of horizontal gene transfer mediates the translocation of large DNA fragments between two bacterial cells in direct contact. Integrative and conjugative elements (ICEs) of the SXT/R391 family (SRIs) and IncA/C conjugative plasmids (ACPs) are responsible for the dissemination of a broad spectrum of antibiotic resistance genes among diverse species of Enterobacteriaceae and Vibrionaceae. The biology, diversity, prevalence and distribution of these two families of conjugative elements have been the subject of extensive studies for the past 15 years. Recently, the transcriptional regulators that govern their dissemination through the expression of ICE- or plasmid-encoded transfer genes have been described. Unrelated repressors control the activation of conjugation by preventing the expression of two related master activator complexes in both types of elements, i.e., SetCD in SXT/R391 ICEs and AcaCD in IncA/C plasmids. Finally, in addition to activating ICE- or plasmid-borne genes, these master activators have been shown to specifically activate phylogenetically unrelated mobilizable genomic islands (MGIs) that also disseminate antibiotic resistance genes and other adaptive traits among a plethora of pathogens such as Vibrio cholerae and Salmonella enterica.

No MeSH data available.


Related in: MedlinePlus