Staphylococcus aureus plasmids without mobilization genes are mobilized by a novel conjugative plasmid from community isolates

O’Brien, Frances; Ramsay, Joshua P.; Monecke, Stefan; Coombs, Geoffrey W.; Robinson, Owen; Htet, Z.; Alshaikh, F. A. M.; Grubb, W.B.

doi:10.1093/jac/dku454

Cited by 27 publications

(34 citation statements)

References 15 publications

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“…Interestingly, the oriT mimic sequence found in pCA347 is identical to a sequence found in pWBG757, a plasmid that could not be mobilized with pWBG749 in studies by O'Brien and colleagues (17). Comparative data such as these may allow us to classify mobilizable plasmids into families related to the relaxase(s) used for transmobilization.…”

Section: Discussionmentioning

confidence: 95%

“…3A and B). Interestingly, within the predicted DNA hairpins of pSK156 and pCA347, nucleotides at the base of the DNA hairpin (G 3 , C 17 , and G 18 ) are conserved with the sequence of pSK41 (Fig. 3A and C to E).…”

Section: Resultsmentioning

confidence: 99%

“…3D and E). Because C 17 and G 18 are conserved in both pSK156 and pCA347, the contacts via G153, N154, and R151 are maintained. The cytosine at position 19 in pSK41 is replaced by a thymine in pSK156 and pCA347; however, the para-oxygen of thymine appears to be capable of receiving a hydrogen bond from Y156 of NES.…”

Section: Resultsmentioning

confidence: 99%

“…Comparative data such as these may allow us to classify mobilizable plasmids into families related to the relaxase(s) used for transmobilization. The oriT mimic sequence of pSK156 is also found in plasmid pWBG747, which could be mobilized by pWBG749, suggesting that pWBG747 harbors two distinct originof-transfer sequences to maximize its ability to be transferred (17,18).…”

Section: Discussionmentioning

confidence: 99%

“…Recently, O'Brien et al showed that another staphylococcal conjugative plasmid, pWBG749, which is unrelated to pSK41, can facilitate the mobilization of other plasmids that lack mob genes (17). They demonstrated that this transfer is facilitated by origin-oftransfer sequences on the mobilizable plasmids that mimic the pWBG749 origin-of-transfer sequence, suggesting a conjugative relaxase in trans mechanism (18).…”

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confidence: 99%

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Processing of Nonconjugative Resistance Plasmids by Conjugation Nicking Enzyme of Staphylococci

et al. 2016

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Antimicrobial resistance in Staphylococcus aureus presents an increasing threat to human health. This resistance is often encoded on mobile plasmids, such as pSK41; however, the mechanism of transfer of these plasmids is not well understood. In this study, we first examine key protein-DNA interactions formed by the relaxase enzyme, NES, which initiates and terminates the transfer of the multidrug resistance plasmid pSK41. Two loops on the NES protein, hairpin loops 1 and 2, form extensive contacts with the DNA hairpin formed at the oriT region of pSK41, and here we establish that these contacts are essential for proper DNA cleavage and religation by the full 665-residue NES protein in vitro. Second, pSK156 and pCA347 are nonconjugative Staphylococcus aureus plasmids that contain sequences similar to the oriT region of pSK41 but differ in the sequence predicted to form a DNA hairpin. We show that pSK41-encoded NES is able to bind, cleave, and religate the oriT sequences of these nonconjugative plasmids in vitro. Although pSK41 could mobilize a coresident plasmid harboring its cognate oriT, it was unable to mobilize plasmids containing the pSK156 and pCA347 variant oriT mimics, suggesting that an accessory protein like that previously shown to confer specificity in the pWBG749 system may also be involved in transmission of plasmids containing a pSK41-like oriT. These data indicate that the conjugative relaxase in trans mechanism recently described for the pWBG749 family of plasmids also applies to the pSK41 family of plasmids, further heightening the potential significance of this mechanism in the horizontal transfer of staphylococcal plasmids. IMPORTANCEUnderstanding the mechanism of antimicrobial resistance transfer in bacteria such as Staphylococcus aureus is an important step toward potentially slowing the spread of antimicrobial-resistant infections. This work establishes protein-DNA interactions essential for the transfer of the Staphylococcus aureus multiresistance plasmid pSK41 by its relaxase, NES. This enzyme also processed variant oriT-like sequences found on numerous plasmids previously considered nontransmissible, suggesting that in conjunction with an uncharacterized accessory protein, these plasmids may be transferred horizontally via a relaxase in trans mechanism. These findings have important implications for our understanding of staphylococcal resistance plasmid evolution.

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Section: Discussionmentioning

confidence: 95%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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