Co-Transduction of Plasmids Mediating Resistance to Tetracycline and Chloramphenicol in Staphylococcus aureus

Transduction of plasmid pC194 and bacteriophage 4llde varied inversely with the multiplicity of infection. As the multiplicity of infection decreased from 10-' to 10-5 PFU/CFU, the transduction frequency of pC194 increased 104-fold; the transduction frequency of 4llde increased 300-fold with a 100-fold decrease in multiplicity of infection. Physical and genetic analysis of the transduced DNA showed that pC194 resided in the phage particle as a random, circularly permuted linear concatemer. In DNA prepared from phage that cotransduced pC194 and 411de, pC194 resided in the transducing phage primarily as a linear multimer of 15.8 kilobases, or about 5.4 pC194 monomers. The pC194 multimer was randomly inserted into the 411 genome.Small staphylococcal plasmids are not transduced by generalized transduction, as are chromosomal determinants (2,27). This was first shown by Grubb et al. (6,7), who demonstrated cotransduction of staphylococcal streptomycin resistance and tetracycline resistance plasmids. Later, Stiffler et al. (26) and Iordanescu (10) extended this observation to include a variety of other small plasmids. These investigations highlight a dilemma that arises because cotransduction of plasmid DNA in Staphylococcus spp. often occurs at frequencies higher than predicted for a random packaging model. Transduction of a single plasmid species occurs at frequencies of about 10-5 to 10-8 per PFU; frequencies vary depending upon the plasmid used and the transducing phage (2). Other unselected plasmids are often cotransduced at between 1 and 10% of the single transduction frequency (9), even though the predicted cotransduction rates for randomly packaged plasmids should be the product of the probabilities of the single transductional events. This high rate leads to the suggestion that cotransducing plasmids are not randomly assorted, but associate in some specific way. Iordanescu (10) suggested that some staphylococcal plasmids become transiently associated during the formation of the transducing particle. Furthermore, this transient association is limited to specific pairs that share short regions of homology (14). Cotransduced plasmids generally resolve into individual replicons in the recipient cell, but occasionally (ca. 1%) the plasmid phenotypes remain associated as stable plasmid cointegrates that arise from site-and orientation-specific recombination (14). Plasmid cointegrates are stable in subsequent transductions or transformations and do not under normal circumstances dissociate into the component replicons (9).Examination of these transient transductional associations has been complicated by the assumption that these events occur at relatively low frequencies in a transducing phage population. However, we have utilized the finding that plasmid transduction occurs at higher rates at very low multiplicity of infection (MOI) (19,20) to directly analyze the transducing DNA in the phage particles. * Corresponding author. t Contribution no. 85-82-J from the Kansas Agricultural Experiment Station, Manhattan. t ...

mentioning

confidence: 76%

mentioning

confidence: 92%

Generation of transducing particles in Staphylococcus aureus

Dyer¹,

Rock²,

Lee³

et al. 1985

“…Indeed, the use of the term "chromosome" with reference to S. aureus is quite properly qualified to refer to "the genophore(s) that corresponds to the chromosome in other bacteria" (9). As the sole means for direct genetic analysis in S. aureus until recently, generalized transduction has nonetheless been immensely useful for fine-structure genetic analysis (15) and for the genetic characterization of plasmids (8,24). Because of the limited size (8) and apparent homogeneity (14) of the transducing fragments, however, generalized transduction has been of limited value in studying the gross organization of the staphylococcal chromosome.…”

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confidence: 99%

Transformation analysis of three linkage groups in Staphylococcus aureus

Pattee¹,

Neveln²

1975

131

While studying a set of multiply marked mutants of Staphylococcus aureus strain 8325 by transformation, several instances of apparent genetic linkage were encountered. After showing that these linked transformations were readily inactivated by shearing of the deoxyribonucleic acid (DNA) but were resistant to dilution of the DNA, and showing that mixtures of DNA failed to form double transformants, it was concluded that the linkages were legitimate rather than the result of congression. Three linkage groups were defined: thy-101-lys-115-trp-103-thr-106, pyr-141-hisGb15-nov-pur-102, and pur-110-ilv-129. The positions of the previously studied trp and his operons corresponded to the trp-103 and hisGbl5 loci. The ilv-129 position adjacent to pur-l10 probably corresponds to the ilv-leu gene cluster. The distance over which linkage was detected was greater by transformation than by generalized transduction. 201 on August 11, 2020 by guest http://jb.asm.org/ Downloaded from for 30 min on a Burrell wrist-action shaker (Burrell distilled (under N2) phenol saturated with 0.01 Corp., Pittsburgh, Pa.). The lysis mixtures were then M Tris(hydroxymethylfaminomethane-hydrochloride extracted three times with equal volumes of freshly buffer, pH 8.

“…The mechanism of the cotransduction of distinct plasmids is not yet clear. The plasmids found in cotransductants were reported to be independent and apparently identical with the original plasmids (5,15). Moreover, no co-integrate forms could be isolated from cells carrying cotransducible plasmids (14,15).…”

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confidence: 98%

“…The simultaneous transduction of several plasmid-borne markers represents an important argument for their presence on the same plasmid (1,13). The cotransduction of independent plasmids was, however, reported in several instances in Escherichia coli (2) as well as in Staphylococcus aureus (4,14,15). In S. aureus, only the plasmids belonging to the small-size class (12) carrying a single resistance marker seem to be implicated in cotransduction.…”

mentioning

confidence: 99%

Relationships between cotransducible plasmids in Staphylococcus aureus

Iordănescu¹

1977

Cotransduction of two or even three plasmids was observed when a Staphylococcus aureus strain, carrying five distinct, compatible plasmids, was used as donor. An active host recombination system did not seem to be indispensable for plasmid cotransduction, since RecA+ and RecA- donors gave similar cotransduction frequencies. Analysis of plasmids carried by cotransductant clones demonstrated that a genetic interaction can take place between cotransduced plasmids, leading to new plasmids. Some of the properties of these new plasmids are discussed. Another set of experiments tested the ability of a cotransducible plasmid to allow a significant degree of multiplication of a temperature-sensitive plasmid at restrictive temperature. In an attempt to explain the results obtained, a working hypothesis suggesting a transient and reversible association of cotransducible plasmids is presented.