Role of the origin of transfer in termination of strand transfer during bacterial conjugation

Bhattacharjee, Mrinal K.; Rao, Xiao‐Mei; Meyer, Richard J.

doi:10.1128/jb.174.20.6659-6665.1992

Cited by 36 publications

(34 citation statements)

References 21 publications

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“…A different termination nicking reaction for R1162 was engineered by placing a second oriT "downstream" from the first, in terms of the direction of DNA transfer. The termination/recircularization event at the second oriT was prevented if the inverted repeat within this oriT was removed, consistent with the hypothesis described above (81).…”

Section: Dna Recircularization Complementary Strand Synthesis and Vsupporting

confidence: 72%

Conjugative transfer in the dissemination of beta-lactam and aminoglycoside resistance

Waters¹

1999

Front Biosci

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The dissemination of antibiotic resistance among pathogenic bacteria can be attributed largely to conjugative DNA transfer. The general category of conjugative transfer includes both bacterial plasmid conjugation and the transfer of nonreplicative conjugative transposons. Prototypes for these two systems are the plasmid RK2 and the conjugative transposon Tn916. To address the long-term problem of the increasing prevalence and severity of antibiotic resistance, strategies aimed against conjugative transfer are needed, but their development will require a greater understanding of conjugative resistance gene acquisition. Overviews of the two conjugative transfer systems are presented, to summarize and compare current concepts. Observations regarding transfer of conjugative transposons is consistent with the prevailing model for plasmid conjugation, that is, by the transfer of a single-stranded DNA molecule from the donor to the recipient bacterium, and the generation of the single strand by rolling circle DNA replication. The relevance of vegetative plasmid replication and host range to the spread of multiple drug resistance is discussed, and clinical examples of conjugative transfer of multiple antibiotic resistance illustrate the severity of the current situation. Possible directions, traditional and innovative, are offered to address the conjugative transfer problem in drug resistance, and potentially to break the cycle of antibiotic development followed by the bacterial resistance gene acquisition.

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Section: Dna Recircularization Complementary Strand Synthesis and Vsupporting

confidence: 72%

Conjugative transfer in the dissemination of beta-lactam and aminoglycoside resistance

Waters¹

1999

Front Biosci

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“…We have suggested that these steps involve the same reaction, carried out by the MobA protein and requiring a similar substrate (Zhang and Meyer, 1995). In each case, MobA cleaves within a single-stranded region, but requires adjacent duplex DNA at the inner arm of the inverted repeat for tight binding (Bhattacharjee et al, 1992;Bhattacharjee and Meyer, 1993). In the case of the single, transferred strand, a duplex structure adjacent to the cleavage site is generated by basepairing between the arms of the inverted repeat (Barlett et al, 1990;Bhattacharjee and Meyer, 1993).…”

Section: Discussionmentioning

confidence: 99%

“…Plasmids used in this study are listed in Table 3. Conjugal matings were carried out on semi-solid media essentially as described in previous publications (Brasch and Meyer, 1986;Bhattacharjee et al, 1992), with donor MV10 or LE316 cells containing the IncP-1 plasmid R751 as mobilizing vector (Willetts and Crowther, 1981). The recipient strain was DF1019, a C600 derivative resistant to nalidixic acid (Figurski et al, 1976).…”

Section: Strains Plasmids and Bacteriological Proceduresmentioning

confidence: 99%

The relaxosome protein MobC promotes conjugal plasmid mobilization by extending DNA strand separation to the nick site at the origin of transfer

Zhang

Meyer

1997

Molecular Microbiology

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SummaryThe frequency of conjugal mobilization of plasmid R1162 is decreased approximately 50-fold if donor cells lack MobC, one of the plasmid-encoded proteins making up the relaxosome at the origin of transfer (oriT ). The absence of MobC has several different effects on oriT DNA. Site-and strand-specific nicking by MobA protein is severely reduced, accounting for the lower frequency of mobilization. The localized DNA strand separation required for this nicking is less affected, but becomes more sensitive to the level of active DNA gyrase in the cell. In addition, strand separation is not efficiently extended through the region containing the nick site. These effects suggest a model in which MobC acts as a molecular wedge for the relaxosome-induced melting of oriT DNA. The effect of MobC on strand separation may be partially complemented by the helical distortion induced by supercoiling. However, MobC extends the melted region through the nick site, thus providing the single-stranded substrate required for cleavage by MobA.

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“…Three R1162 proteins, MobA, MobB, and MobC, form a protein-DNA complex called the relaxosome at oriT (27). From the mobilization experiments with recombinant plasmids containing two tandemly repeated oriT sequences with or without mutations, the 10-bp inverted repeat structure as well as the sequence around the nick site was shown to be required for termination, while the nick site-distal arm of the inverted repeat was not required for initiation (1). From the analyses of mutations introduced into the 10-bp repeat, it has been postulated that during termination of DNA transfer, formation of a hairpin loop structure by the inverted repeat is required for the resealing of the transferred DNA by the R1162 MobA relaxase (32).…”

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confidence: 99%

Initiation and Termination of DNA Transfer during Conjugation of IncI1 Plasmid R64: Roles of Two Sets of Inverted Repeat Sequences within oriT in Termination of R64 Transfer

Furuya

Komano

2000

J Bacteriol

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Intercellular transfer of plasmid DNA during bacterial conjugation initiates and terminates at a specific origin of transfer, oriT. We have investigated the oriT structure of conjugative plasmid R64 with regard to the initiation and termination of DNA transfer. Using recombinant plasmids containing two tandemly repeated R64 oriT sequences with or without mutations, the subregions required for initiation and termination were determined by examining conjugation-mediated deletion between the repeated oriTs. The oriT subregion required for initiation was found to be identical to the 44-bp oriT core sequence consisting of two units, the conserved nick region sequence and the 17-bp repeat A sequence, that are recognized by R64 relaxosome proteins NikB and NikA, respectively. In contrast, the nick region sequence and two sets of inverted repeat sequences within the 92-bp minimal oriT sequence were required for efficient termination. Mutant repeat A sequences lacking NikA-binding ability were found to be sufficient for termination, suggesting that the inverted repeat structures are involved in the termination process. A duplication of the DNA segment between the repeated oriTs was also found after mobilization of the plasmid carrying initiation-deficient but terminationproficient oriT and initiation-proficient but termination-deficient oriT, suggesting that the 3 terminus of the transferred strand is elongated by rolling-circle-DNA synthesis.Intercellular transfer of plasmid DNA during bacterial conjugation is accomplished by the function of transfer genes borne on each conjugative plasmid (for reviews, see references 4 and 15). All conjugative and mobilizable plasmids, such as R64, F, RP4, and R1162, contain oriT sites as cis elements which function as the origin of transfer of plasmid DNA. At the initiation stage of DNA transfer, a site-and strand-specific nick is introduced into the oriT site with a covalent attachment of the cognate relaxase protein to the 5Ј terminus of the nicked strand. The nicked strand is transferred from donor to recipient cells with the 5Ј terminus leading through a putative channel. In the donor cells, replacement strand DNA synthesis reconstitutes the double-stranded plasmid DNA. After one round of DNA transfer, the relaxase-attached 5Ј terminus of the transferred-strand DNA is religated to its 3Ј terminus to reconstitute the circular structure, and complementary-strand synthesis establishes double-stranded plasmid DNA in the recipient cells. Among these steps, the mechanisms by which initiation and termination of conjugative DNA transfer occur are important issues which remain to be elucidated.Initiation and termination of conjugative DNA transfer at the oriT site were extensively studied using a small mobilizable plasmid, R1162 (RSF1010). R1162 oriT consists of a specific nick site and a 10-bp inverted repeat with one mismatch, which is situated 8 bp from the nick site (3, 27). Three R1162 proteins, MobA, MobB, and MobC, form a protein-DNA complex called the relaxosome at oriT (27). From ...

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Role of the origin of transfer in termination of strand transfer during bacterial conjugation

Cited by 36 publications

References 21 publications

Conjugative transfer in the dissemination of beta-lactam and aminoglycoside resistance

Conjugative transfer in the dissemination of beta-lactam and aminoglycoside resistance

The relaxosome protein MobC promotes conjugal plasmid mobilization by extending DNA strand separation to the nick site at the origin of transfer

Initiation and Termination of DNA Transfer during Conjugation of IncI1 Plasmid R64: Roles of Two Sets of Inverted Repeat Sequences within oriT in Termination of R64 Transfer

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