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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

Activation by heteromeric complexes SetCD and AcaCD. (A) Experimentally determined recognition motifs of SetCD and AcaCD (Carraro et al., 2014a; Poulin-Laprade et al., 2015). (B) Representation of SetCD targets in SRIs and in MGIs they mobilize. The arrows indicate transcriptional repression by SetR (minus sign) and transcriptional activation by SetCD (plus signs). (C) Representation of AcaCD targets in ACPs and in MGIs from MGIVmi1 and SGI1 families. The arrows indicate transcriptional repression by Acr1 and Acr2 (minus sign) and transcriptional activation by AcaCD (plus signs). In both B and C panels, the modules of DNA processing (mob) and mating pair formation (mpf) are indicated and color-coded as described in Figure 1 legend.
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Figure 3: Activation by heteromeric complexes SetCD and AcaCD. (A) Experimentally determined recognition motifs of SetCD and AcaCD (Carraro et al., 2014a; Poulin-Laprade et al., 2015). (B) Representation of SetCD targets in SRIs and in MGIs they mobilize. The arrows indicate transcriptional repression by SetR (minus sign) and transcriptional activation by SetCD (plus signs). (C) Representation of AcaCD targets in ACPs and in MGIs from MGIVmi1 and SGI1 families. The arrows indicate transcriptional repression by Acr1 and Acr2 (minus sign) and transcriptional activation by AcaCD (plus signs). In both B and C panels, the modules of DNA processing (mob) and mating pair formation (mpf) are indicated and color-coded as described in Figure 1 legend.

Mentions: A similar experimental approach also allowed to establish the list of the promoters targeted by AcaCD in pVCR94ΔX, a prototypical ACP lacking most of its resistance genes (Carraro et al., 2014a,b). The DNA motifs recognized by SetCD and AcaCD were deduced from the multiple targets that were experimentally determined. Operator sites for SetCD and AcaCD fixation greatly differ from each other, and from the DNA motif recognized by E. coli FlhCD (Figure 3A; Carraro et al., 2014a; Fitzgerald et al., 2014; Poulin-Laprade et al., 2015). Despite their functional homology, SetCD, AcaCD, and FlhCD exhibit a high degree of divergence, which is reflected in their respective DNA target preference and specificity (Liu and Matsumura, 1994; Carraro et al., 2014a; Fitzgerald et al., 2014; Poulin-Laprade et al., 2015).


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)

Activation by heteromeric complexes SetCD and AcaCD. (A) Experimentally determined recognition motifs of SetCD and AcaCD (Carraro et al., 2014a; Poulin-Laprade et al., 2015). (B) Representation of SetCD targets in SRIs and in MGIs they mobilize. The arrows indicate transcriptional repression by SetR (minus sign) and transcriptional activation by SetCD (plus signs). (C) Representation of AcaCD targets in ACPs and in MGIs from MGIVmi1 and SGI1 families. The arrows indicate transcriptional repression by Acr1 and Acr2 (minus sign) and transcriptional activation by AcaCD (plus signs). In both B and C panels, the modules of DNA processing (mob) and mating pair formation (mpf) are indicated and color-coded as described in Figure 1 legend.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 3: Activation by heteromeric complexes SetCD and AcaCD. (A) Experimentally determined recognition motifs of SetCD and AcaCD (Carraro et al., 2014a; Poulin-Laprade et al., 2015). (B) Representation of SetCD targets in SRIs and in MGIs they mobilize. The arrows indicate transcriptional repression by SetR (minus sign) and transcriptional activation by SetCD (plus signs). (C) Representation of AcaCD targets in ACPs and in MGIs from MGIVmi1 and SGI1 families. The arrows indicate transcriptional repression by Acr1 and Acr2 (minus sign) and transcriptional activation by AcaCD (plus signs). In both B and C panels, the modules of DNA processing (mob) and mating pair formation (mpf) are indicated and color-coded as described in Figure 1 legend.
Mentions: A similar experimental approach also allowed to establish the list of the promoters targeted by AcaCD in pVCR94ΔX, a prototypical ACP lacking most of its resistance genes (Carraro et al., 2014a,b). The DNA motifs recognized by SetCD and AcaCD were deduced from the multiple targets that were experimentally determined. Operator sites for SetCD and AcaCD fixation greatly differ from each other, and from the DNA motif recognized by E. coli FlhCD (Figure 3A; Carraro et al., 2014a; Fitzgerald et al., 2014; Poulin-Laprade et al., 2015). Despite their functional homology, SetCD, AcaCD, and FlhCD exhibit a high degree of divergence, which is reflected in their respective DNA target preference and specificity (Liu and Matsumura, 1994; Carraro et al., 2014a; Fitzgerald et al., 2014; Poulin-Laprade et al., 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