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An insertion sequence-dependent plasmid rearrangement in Aeromonas salmonicida causes the loss of the type three secretion system.

Tanaka KH, Dallaire-Dufresne S, Daher RK, Frenette M, Charette SJ - PLoS ONE (2012)

Bottom Line: Nine out of the 26 strains had a positive PCR result, suggesting that the rearrangement in these strains were IS-dependent.Our results suggested that pAsa5 rearrangements involve IS11.This is the first study showing that ISs are involved in plasmid instability in A. salmonicida.

View Article: PubMed Central - PubMed

Affiliation: Institut de biologie intégrative et des systèmes, Pavillon Charles-Eugène-Marchand, Université Laval, Quebec City, Quebec, Canada.

ABSTRACT
Aeromonas salmonicida, a bacterial fish pathogen, possesses a functional Type Three Secretion System (TTSS), which is essential for its virulence. The genes for this system are mainly located in a single region of the large pAsa5 plasmid. Bacteria lose the TTSS region from this plasmid through rearrangements when grown in stressful growth conditions. The A. salmonicida genome is rich in insertion sequences (ISs), which are mobile DNA elements that can cause DNA rearrangements in other bacterial species. pAsa5 possesses numerous ISs. Three IS11s from the IS256 family encircle the rearranged regions. To confirm that these IS11s are involved in pAsa5 rearrangements, 26 strains derived from strain A449 and two Canadian isolates (01-B526 and 01-B516) with a pAsa5 rearrangement were tested using a PCR approach to determine whether the rearrangements were the result of an IS11-dependent process. Nine out of the 26 strains had a positive PCR result, suggesting that the rearrangement in these strains were IS-dependent. The PCR analysis showed that all the rearrangements in the A449-derived strains were IS11-dependent process while the rearrangements in 01-B526 and 01-B516 could only be partially coupled to the action of IS11. Unidentified elements that affect IS-dependent rearrangements may be present in 01-B526 and 01-B516. Our results suggested that pAsa5 rearrangements involve IS11. This is the first study showing that ISs are involved in plasmid instability in A. salmonicida.

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Related in: MedlinePlus

IS11-dependent A–C and B–C rearrangements are involved in loss profiles 2 and 1, respectively.A449-R1 derivative strain harboring a loss profile 1 (A) and A449-R2 derivative strain harboring a loss profile 2 (B) were assessed by PCR, using exsD, traC and resD primers as control (Figure 2B). Primers 11B1F and 11CR were used to assess B–C rearrangement while primers 11AF and 11CR were used to assess A–C rearrangement.
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pone-0033725-g003: IS11-dependent A–C and B–C rearrangements are involved in loss profiles 2 and 1, respectively.A449-R1 derivative strain harboring a loss profile 1 (A) and A449-R2 derivative strain harboring a loss profile 2 (B) were assessed by PCR, using exsD, traC and resD primers as control (Figure 2B). Primers 11B1F and 11CR were used to assess B–C rearrangement while primers 11AF and 11CR were used to assess A–C rearrangement.

Mentions: As expected, IS11-dependent rearrangements in pAsa5 that led to the loss of TTSS were detected by PCR. Figure 3 shows that B–C and A–C rearrangements were detected by PCR in the A449 derivatives. Control primers targeting the traC, exsD, and resD genes (Figure 2B) were used to confirm the loss profile previously determined by extended genotyping [10] (Figure 3). The exsD primers confirmed the presence of the TTSS region, while the traC and resD primers confirmed the presence of regions upstream and downstream from TTSS, respectively. The loss of PCR signal for exsD confirmed type 1 loss profile for A449-R1 (Figure 3A), while the loss of PCR signal for exsD and traC confirmed type 2 loss profile for A449-R2 (Figure 3B). The B–C rearrangement was associated with type 1 loss profile of the A449-R1 derivative for which a PCR product was generated with 11B1F-11CR primer pair (Figure 3A). The A-C rearrangement was associated with type 2 loss profile of the A449-R2 derivative for which a PCR product was generated with 11AF-11CR primer pair (Figure 3B). These results indicated that the rearrangements observed in pAsa5 involve IS11s flanking the lost region.


An insertion sequence-dependent plasmid rearrangement in Aeromonas salmonicida causes the loss of the type three secretion system.

Tanaka KH, Dallaire-Dufresne S, Daher RK, Frenette M, Charette SJ - PLoS ONE (2012)

IS11-dependent A–C and B–C rearrangements are involved in loss profiles 2 and 1, respectively.A449-R1 derivative strain harboring a loss profile 1 (A) and A449-R2 derivative strain harboring a loss profile 2 (B) were assessed by PCR, using exsD, traC and resD primers as control (Figure 2B). Primers 11B1F and 11CR were used to assess B–C rearrangement while primers 11AF and 11CR were used to assess A–C rearrangement.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3303853&req=5

pone-0033725-g003: IS11-dependent A–C and B–C rearrangements are involved in loss profiles 2 and 1, respectively.A449-R1 derivative strain harboring a loss profile 1 (A) and A449-R2 derivative strain harboring a loss profile 2 (B) were assessed by PCR, using exsD, traC and resD primers as control (Figure 2B). Primers 11B1F and 11CR were used to assess B–C rearrangement while primers 11AF and 11CR were used to assess A–C rearrangement.
Mentions: As expected, IS11-dependent rearrangements in pAsa5 that led to the loss of TTSS were detected by PCR. Figure 3 shows that B–C and A–C rearrangements were detected by PCR in the A449 derivatives. Control primers targeting the traC, exsD, and resD genes (Figure 2B) were used to confirm the loss profile previously determined by extended genotyping [10] (Figure 3). The exsD primers confirmed the presence of the TTSS region, while the traC and resD primers confirmed the presence of regions upstream and downstream from TTSS, respectively. The loss of PCR signal for exsD confirmed type 1 loss profile for A449-R1 (Figure 3A), while the loss of PCR signal for exsD and traC confirmed type 2 loss profile for A449-R2 (Figure 3B). The B–C rearrangement was associated with type 1 loss profile of the A449-R1 derivative for which a PCR product was generated with 11B1F-11CR primer pair (Figure 3A). The A-C rearrangement was associated with type 2 loss profile of the A449-R2 derivative for which a PCR product was generated with 11AF-11CR primer pair (Figure 3B). These results indicated that the rearrangements observed in pAsa5 involve IS11s flanking the lost region.

Bottom Line: Nine out of the 26 strains had a positive PCR result, suggesting that the rearrangement in these strains were IS-dependent.Our results suggested that pAsa5 rearrangements involve IS11.This is the first study showing that ISs are involved in plasmid instability in A. salmonicida.

View Article: PubMed Central - PubMed

Affiliation: Institut de biologie intégrative et des systèmes, Pavillon Charles-Eugène-Marchand, Université Laval, Quebec City, Quebec, Canada.

ABSTRACT
Aeromonas salmonicida, a bacterial fish pathogen, possesses a functional Type Three Secretion System (TTSS), which is essential for its virulence. The genes for this system are mainly located in a single region of the large pAsa5 plasmid. Bacteria lose the TTSS region from this plasmid through rearrangements when grown in stressful growth conditions. The A. salmonicida genome is rich in insertion sequences (ISs), which are mobile DNA elements that can cause DNA rearrangements in other bacterial species. pAsa5 possesses numerous ISs. Three IS11s from the IS256 family encircle the rearranged regions. To confirm that these IS11s are involved in pAsa5 rearrangements, 26 strains derived from strain A449 and two Canadian isolates (01-B526 and 01-B516) with a pAsa5 rearrangement were tested using a PCR approach to determine whether the rearrangements were the result of an IS11-dependent process. Nine out of the 26 strains had a positive PCR result, suggesting that the rearrangement in these strains were IS-dependent. The PCR analysis showed that all the rearrangements in the A449-derived strains were IS11-dependent process while the rearrangements in 01-B526 and 01-B516 could only be partially coupled to the action of IS11. Unidentified elements that affect IS-dependent rearrangements may be present in 01-B526 and 01-B516. Our results suggested that pAsa5 rearrangements involve IS11. This is the first study showing that ISs are involved in plasmid instability in A. salmonicida.

Show MeSH
Related in: MedlinePlus