Limits...
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.

Show MeSH

Related in: MedlinePlus

Schematic representation of the outcome of the conjugative transfer of the YU39 IncA/C plasmid-borne blaCMY-2 gene to different recipient strains. On the left side is the donor strain YU39 harboring pA/C, pX1 and pColE1-like plasmids. In the middle, The first round conjugation frequencies are indicated above the black arrows along with the recipient strains involved in the different phenomena. The three different types of transconjugants observed for the first round are depicted. The pSTV and pColE1-like plasmids are shown, although they were not present in all the transconjugants. Electroporation step to DH5α for the transconjugants plasmids is represented with the grey arrows. Following are the range of the second round conjugation frequencies in the “original” and DH5α strains (see text for details).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4222815&req=5

Figure 7: Schematic representation of the outcome of the conjugative transfer of the YU39 IncA/C plasmid-borne blaCMY-2 gene to different recipient strains. On the left side is the donor strain YU39 harboring pA/C, pX1 and pColE1-like plasmids. In the middle, The first round conjugation frequencies are indicated above the black arrows along with the recipient strains involved in the different phenomena. The three different types of transconjugants observed for the first round are depicted. The pSTV and pColE1-like plasmids are shown, although they were not present in all the transconjugants. Electroporation step to DH5α for the transconjugants plasmids is represented with the grey arrows. Following are the range of the second round conjugation frequencies in the “original” and DH5α strains (see text for details).

Mentions: In this paper we describe diverse interactions among pA/C, pX1 and pColE1-like plasmids within a single strain. When strain YU39 was challenged for conjugation different phenomena were recorded, depending on the recipient strain. When blaCMY-2 was transferred, three genetic interactions occurred at very low frequencies: 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. Moreover, the trans-mobilization of the pColE1-like plasmid occurred in most of the cases. The general outcome of these processes was the transfer of the blaCMY-2 gene from a non-conjugative pA/C to a highly conjugative pX1 plasmid. Both the resultant pA/C + pX1 and pX1::CMY plasmids acquired the capacity to spread ESC resistance at very high levels by conjugation (Figure 7). This mode of cis-mobilization and transfer of the blaCMY-2 gene has not been previously reported.


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)

Schematic representation of the outcome of the conjugative transfer of the YU39 IncA/C plasmid-borne blaCMY-2 gene to different recipient strains. On the left side is the donor strain YU39 harboring pA/C, pX1 and pColE1-like plasmids. In the middle, The first round conjugation frequencies are indicated above the black arrows along with the recipient strains involved in the different phenomena. The three different types of transconjugants observed for the first round are depicted. The pSTV and pColE1-like plasmids are shown, although they were not present in all the transconjugants. Electroporation step to DH5α for the transconjugants plasmids is represented with the grey arrows. Following are the range of the second round conjugation frequencies in the “original” and DH5α strains (see text for details).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 7: Schematic representation of the outcome of the conjugative transfer of the YU39 IncA/C plasmid-borne blaCMY-2 gene to different recipient strains. On the left side is the donor strain YU39 harboring pA/C, pX1 and pColE1-like plasmids. In the middle, The first round conjugation frequencies are indicated above the black arrows along with the recipient strains involved in the different phenomena. The three different types of transconjugants observed for the first round are depicted. The pSTV and pColE1-like plasmids are shown, although they were not present in all the transconjugants. Electroporation step to DH5α for the transconjugants plasmids is represented with the grey arrows. Following are the range of the second round conjugation frequencies in the “original” and DH5α strains (see text for details).
Mentions: In this paper we describe diverse interactions among pA/C, pX1 and pColE1-like plasmids within a single strain. When strain YU39 was challenged for conjugation different phenomena were recorded, depending on the recipient strain. When blaCMY-2 was transferred, three genetic interactions occurred at very low frequencies: 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. Moreover, the trans-mobilization of the pColE1-like plasmid occurred in most of the cases. The general outcome of these processes was the transfer of the blaCMY-2 gene from a non-conjugative pA/C to a highly conjugative pX1 plasmid. Both the resultant pA/C + pX1 and pX1::CMY plasmids acquired the capacity to spread ESC resistance at very high levels by conjugation (Figure 7). This mode of cis-mobilization and transfer of the blaCMY-2 gene has not been previously reported.

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