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Conjugative transfer of an IncA/C plasmid-borne blaCMY-2 gene through genetic re-arrangements with an IncX1 plasmid.

Wiesner M, Fernández-Mora M, Cevallos MA, Zavala-Alvarado C, Zaidi MB, Calva E, Silva C - BMC Microbiol. (2013)

Bottom Line: The presence of pSTV in the recipients had little effect on the conjugation frequency.The transconjugant plasmids involving pX1 re-arrangements (either via co-integration or ISEcp1-mediated transposition) obtained the capacity to conjugate at very high levels, similar to those found for pX1 (10-1).Two versions of the region containing blaCMY-2 were found to transpose to pX1: the large version was inserted into an intergenic region located where the "genetic load" operons are frequently inserted into pX1, while the short version was inserted into the stbDE operon involved in plasmid addiction system.

View Article: PubMed Central - HTML - PubMed

Affiliation: Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apartado Postal 510-3, Cuernavaca, Morelos, México. csilvamex1@yahoo.com.

ABSTRACT

Background: Our observation that in the Mexican Salmonella Typhimurium population none of the ST19 and ST213 strains harbored both the Salmonella virulence plasmid (pSTV) and the prevalent IncA/C plasmid (pA/C) led us to hypothesize that restriction to horizontal transfer of these plasmids existed. We designed a conjugation scheme using ST213 strain YU39 as donor of the blaCMY-2 gene (conferring resistance to ceftriaxone; CRO) carried by pA/C, and two E. coli lab strains (DH5α and HB101) and two Typhimurium ST19 strains (SO1 and LT2) carrying pSTV as recipients. The aim of this study was to determine if the genetic background of the different recipient strains affected the transfer frequencies of pA/C.

Results: YU39 was able to transfer CRO resistance, via a novel conjugative mechanism, to all the recipient strains although at low frequencies (10-7 to 10-10). The presence of pSTV in the recipients had little effect on the conjugation frequency. The analysis of the transconjugants showed that three different phenomena were occurring associated to the transfer of blaCMY-2: 1) the co-integration of pA/C and pX1; 2) the transposition of the CMY region from pA/C to pX1; or 3) the rearrangement of pA/C. In addition, the co-lateral mobilization of a small (5 kb) ColE1-like plasmid was observed. The transconjugant plasmids involving pX1 re-arrangements (either via co-integration or ISEcp1-mediated transposition) obtained the capacity to conjugate at very high levels, similar to those found for pX1 (10-1). Two versions of the region containing blaCMY-2 were found to transpose to pX1: the large version was inserted into an intergenic region located where the "genetic load" operons are frequently inserted into pX1, while the short version was inserted into the stbDE operon involved in plasmid addiction system. This is the first study to report the acquisition of an extended spectrum cephalosporin (ESC)-resistance gene by an IncX1 plasmid.

Conclusions: We showed that the transfer of the YU39 blaCMY-2 gene harbored on a non- conjugative pA/C requires the machinery of a highly conjugative pX1 plasmid. Our experiments demonstrate the complex interactions a single strain can exploit to contend with the challenge of horizontal transfer and antibiotic selective pressure.

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Examples of pA/C transconjugants recovered in SO1 pSTV::Km and DH5α. Panel A) shows the plasmid profiles of four different transconjugants in SO1 marked within dotted rectangles. The donor YU39 pA/C and the recipient SO1pSTV::Km strains are in the first and last lanes, respectively. Within each dotted rectangle, in the first lane are the SO1 transconjugants; in the second and third lanes the DH5α transformants for the pA/C and pSTV of each transconjugant are shown. Panel B) displays examples of PstI restriction profiles of pA/C transconjugants of SO1 and DH5α compared with wild-type YU39 pA/C (DH5α-pA/C).
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Figure 4: Examples of pA/C transconjugants recovered in SO1 pSTV::Km and DH5α. Panel A) shows the plasmid profiles of four different transconjugants in SO1 marked within dotted rectangles. The donor YU39 pA/C and the recipient SO1pSTV::Km strains are in the first and last lanes, respectively. Within each dotted rectangle, in the first lane are the SO1 transconjugants; in the second and third lanes the DH5α transformants for the pA/C and pSTV of each transconjugant are shown. Panel B) displays examples of PstI restriction profiles of pA/C transconjugants of SO1 and DH5α compared with wild-type YU39 pA/C (DH5α-pA/C).

Mentions: PstI restriction profiles for the thirteen pA/C transconjugants selected for detailed analysis (Table 4) showed that in some cases a distinct profile was generated in comparison with that of the wild-type YU39 pA/C transformed into DH5α (DH5α-pA/C). Examples of the plasmid (Figure 4A) and PstI restriction profiles are shown (Figure 4B).


Conjugative transfer of an IncA/C plasmid-borne blaCMY-2 gene through genetic re-arrangements with an IncX1 plasmid.

Wiesner M, Fernández-Mora M, Cevallos MA, Zavala-Alvarado C, Zaidi MB, Calva E, Silva C - BMC Microbiol. (2013)

Examples of pA/C transconjugants recovered in SO1 pSTV::Km and DH5α. Panel A) shows the plasmid profiles of four different transconjugants in SO1 marked within dotted rectangles. The donor YU39 pA/C and the recipient SO1pSTV::Km strains are in the first and last lanes, respectively. Within each dotted rectangle, in the first lane are the SO1 transconjugants; in the second and third lanes the DH5α transformants for the pA/C and pSTV of each transconjugant are shown. Panel B) displays examples of PstI restriction profiles of pA/C transconjugants of SO1 and DH5α compared with wild-type YU39 pA/C (DH5α-pA/C).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4222815&req=5

Figure 4: Examples of pA/C transconjugants recovered in SO1 pSTV::Km and DH5α. Panel A) shows the plasmid profiles of four different transconjugants in SO1 marked within dotted rectangles. The donor YU39 pA/C and the recipient SO1pSTV::Km strains are in the first and last lanes, respectively. Within each dotted rectangle, in the first lane are the SO1 transconjugants; in the second and third lanes the DH5α transformants for the pA/C and pSTV of each transconjugant are shown. Panel B) displays examples of PstI restriction profiles of pA/C transconjugants of SO1 and DH5α compared with wild-type YU39 pA/C (DH5α-pA/C).
Mentions: PstI restriction profiles for the thirteen pA/C transconjugants selected for detailed analysis (Table 4) showed that in some cases a distinct profile was generated in comparison with that of the wild-type YU39 pA/C transformed into DH5α (DH5α-pA/C). Examples of the plasmid (Figure 4A) and PstI restriction profiles are shown (Figure 4B).

Bottom Line: The presence of pSTV in the recipients had little effect on the conjugation frequency.The transconjugant plasmids involving pX1 re-arrangements (either via co-integration or ISEcp1-mediated transposition) obtained the capacity to conjugate at very high levels, similar to those found for pX1 (10-1).Two versions of the region containing blaCMY-2 were found to transpose to pX1: the large version was inserted into an intergenic region located where the "genetic load" operons are frequently inserted into pX1, while the short version was inserted into the stbDE operon involved in plasmid addiction system.

View Article: PubMed Central - HTML - PubMed

Affiliation: Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apartado Postal 510-3, Cuernavaca, Morelos, México. csilvamex1@yahoo.com.

ABSTRACT

Background: Our observation that in the Mexican Salmonella Typhimurium population none of the ST19 and ST213 strains harbored both the Salmonella virulence plasmid (pSTV) and the prevalent IncA/C plasmid (pA/C) led us to hypothesize that restriction to horizontal transfer of these plasmids existed. We designed a conjugation scheme using ST213 strain YU39 as donor of the blaCMY-2 gene (conferring resistance to ceftriaxone; CRO) carried by pA/C, and two E. coli lab strains (DH5α and HB101) and two Typhimurium ST19 strains (SO1 and LT2) carrying pSTV as recipients. The aim of this study was to determine if the genetic background of the different recipient strains affected the transfer frequencies of pA/C.

Results: YU39 was able to transfer CRO resistance, via a novel conjugative mechanism, to all the recipient strains although at low frequencies (10-7 to 10-10). The presence of pSTV in the recipients had little effect on the conjugation frequency. The analysis of the transconjugants showed that three different phenomena were occurring associated to the transfer of blaCMY-2: 1) the co-integration of pA/C and pX1; 2) the transposition of the CMY region from pA/C to pX1; or 3) the rearrangement of pA/C. In addition, the co-lateral mobilization of a small (5 kb) ColE1-like plasmid was observed. The transconjugant plasmids involving pX1 re-arrangements (either via co-integration or ISEcp1-mediated transposition) obtained the capacity to conjugate at very high levels, similar to those found for pX1 (10-1). Two versions of the region containing blaCMY-2 were found to transpose to pX1: the large version was inserted into an intergenic region located where the "genetic load" operons are frequently inserted into pX1, while the short version was inserted into the stbDE operon involved in plasmid addiction system. This is the first study to report the acquisition of an extended spectrum cephalosporin (ESC)-resistance gene by an IncX1 plasmid.

Conclusions: We showed that the transfer of the YU39 blaCMY-2 gene harbored on a non- conjugative pA/C requires the machinery of a highly conjugative pX1 plasmid. Our experiments demonstrate the complex interactions a single strain can exploit to contend with the challenge of horizontal transfer and antibiotic selective pressure.

Show MeSH
Related in: MedlinePlus