Expression of Tn5-encoded streptomycin resistance in E. coli

Mazodier, Philippe; Genilloud, Olga; Giraud, Evelyne; Gasser, F.

doi:10.1007/bf00331016

Cited by 19 publications

(16 citation statements)

References 30 publications

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“…If this differential stability characterizes full-length transcripts in vivo, it would favor a higher ratio of m2 to ml in stationaryphase cells and thus a higher ratio of inhibitor to transposase and so provide an additional level of transposition attenuation. This is particularly interesting since E. coli is probably not the natural host of TnS (20). Since the dam methylation system is rather restricted taxonomically (2), it may well be that the natural host of TnS lacks this system.…”

Section: Discussionmentioning

confidence: 99%

Temporal control of transposition in Tn5

McCommas

Syvanen

1988

J Bacteriol

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ISSOR is an insertion sequence associated with the transposon Tn5. IS50R carries the structural genes for two proteins; one (Pl) is the Tn5 transposase, and the other (P2) is an inhibitor of transposition. These two proteins are translated from two different transcripts, ml and m2. When bacteriophage X::ISSOR DNA was introduced into a bacterial cell, ml and m2 were initially at relative levels of about 1 to 2. As time progressed the amount of ml fell, whereas the amount of m2 continued to increase, until after about 3 h the ratio of ml to m2 was about 1 to 80. The temporal changes in the levels of these transcripts correlated with temporal changes in P1 and P2 levels and Tn5 transposition that have been documented in other studies. We measured the stability of the messages and showed that the differences in the levels of ml and m2 must reflect real differences in the strengths of their promoters and that the changes in transcription kinetics are mediated by the dam methylation system of the cell and are not determined by IS50R products. Our results show that the 5' end of m2 is about twice as stable as that of ml, which raises the possibility that differential message stability does, in part, influence the ratio of inhibitor to transposase.

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Section: Discussionmentioning

confidence: 99%

Temporal control of transposition in Tn5

McCommas

Syvanen

1988

J Bacteriol

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“…These mutations consisted of a 6-base-pair deletion between positions 3519 and 3534, located at the left of the NcoI site (position 3560). A characteristic of this region of str is the repetition of a GGCGA(G or C) sequence (17). Because of these repetitions, the exact position of the deletion could not be localized.…”

Section: Methodsmentioning

confidence: 99%

“…In Escherichia coli, the str gene product is actually synthesized in normal amounts but cells do not express the Smr phenotype (17). However, this expression has been obtained by different means: (i) setting str under the control of a strong promoter (7); (ii) isolating chromosomal mutants which allow expression of str (22); (iii) isolating mutations of the TnS str gene (17,19). These TnS mutations do not affect the levels of transcription and translation of the neo ble str operon.…”

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confidence: 99%

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A clinical isolate of transposon Tn5 expressing streptomycin resistance in Escherichia coli

et al. 1988

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The central region of transposon TnS carries three antibiotic resistance markers: neo, ble, and str. The str gene codes for a phosphotransferase that inactivates streptomycin. This activity is phenotypically expressed in several gram-negative bacteria but not in Escherichia coil. We identified a TnS variant in E. coli clinical isolates that express streptomycin resistance. This transposon carries a 6-base-pair deletion within the str gene, near the 3' end. The same kind of mutation had been previously obtained experimentally from TnS.

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“…The lack of resistance to streptomycin in enteric bacteria carrying transposon Tn5 remains unexplained. Nevertheless, expression of this resistance has been obtained in E. coli by different means: (i) setting str under the control of a strong promoter (8), (ii) selecting chromosomal mutants of E. coli that allow the expression of str (22), and (iii) isolating a Tn5 mutation that is able to express str in E. coli (15). A natural TnS variant that is able to confer streptomycin resistance to E. coli was isolated and characterized in our laboratory (10).…”

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confidence: 99%