Conjugal Transfer in Anaerobic Bacteria

Macrina, Francis L.

doi:10.1007/978-1-4757-9357-4_13

Cited by 9 publications

(9 citation statements)

References 59 publications

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“…A distinctive group of conjugative transposons, which are completely unrelated to Tn916, have been found in the gram-negative anaerobes, especially Bacteroides spp. (22,23,40,44,62,72). The Bacteroides conjugative transposons range in size from 65 to over 150 kbp (3,44).…”

Section: Gram-negative Bacteriamentioning

confidence: 99%

“…Some of the Tc r ERL type elements have an additional segment (about 10 kbp) that contains and Em r gene, ermF (23). Tc r Em r 12256 (also called Tn5030 [23,40]) is a hybrid element, which consists of a Tc r Em r DOT type element inserted into another conjugative transposon not related to the Tc r ERL type conjugative transposons (3,66). XBU4422 is a cryptic element, whose ends resemble those of Tc r ERL but whose interior regions have only scattered regions of homology with Tc r ERL (66).…”

Section: What's In a Name? The Nomenclatural Dilemmamentioning

confidence: 99%

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Conjugative transposons: an unusual and diverse set of integrated gene transfer elements.

Salyers

Shoemaker

Stevens

et al. 1995

Microbiological Reviews

286

127

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Section: Gram-negative Bacteriamentioning

confidence: 99%

Section: What's In a Name? The Nomenclatural Dilemmamentioning

confidence: 99%

Conjugative transposons: an unusual and diverse set of integrated gene transfer elements.

Salyers

Shoemaker

Stevens

et al. 1995

Microbiological Reviews

286

127

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“…Conjugal genetic exchange of these resistance markers in Bacteroides spp. is now well documented (16,(29)(30)(31)(32). Various genetic elements have been shown to be involved, including (i) large conjugative plasmids like pBF4, a 41-kb plasmid from Bacteroides fragilis, or pBI136, an 80-kb plasmid from Bacteroides ovatus; (ii) small mobilizable plasmids like pBFTM10, a 15-kb plasmid from B. fragilis; and (iii) conjugative transposons (Tc r / Tc r Em r elements).…”

mentioning

confidence: 99%

Conjugal transfer of the 5-nitroimidazole resistance plasmid pIP417 from Bacteroides vulgatus BV-17: characterization and nucleotide sequence analysis of the mobilization region

1996

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Three small 5-nitroimidazole (5-Ni) resistance plasmids (pIP417, pIP419, and pIP421) from Bacteroides clinical isolates are transferable by a conjugative process during homologous or heterologous matings. The mobilization properties of pIP417 originated from strain BV-17 of Bacteroides vulgatus were studied. The plasmid was successfully introduced by in vitro conjugation into different strains of Bacteroides and Prevotella species and could be transferred back from these various strains to a plasmid-free 5-Ni-sensitive Bacteroides fragilis strain, indicating that in vivo spread of the resistance gene may occur. The transfer of plasmid pIP417 harbored by the Tc r strain BF-2 of B. fragilis was stimulated by low concentrations of tetracycline or chlorotetracycline. This suggests a possible role for coresident conjugative transposons in the dissemination of 5-Ni resistance among gram-negative anaerobes. The nucleotide sequence of the 2.1-kb DNA mobilization region was determined. It contains a putative origin of transfer (oriT) in an A؉T-rich-region, including three inverted repeats, and two integration host factor binding sites. The two identified mobilization genes (mobA and mobB) are organized in one operon and were both required for efficient transfer. Southern blotting indicated that the mobilization region of plasmid pIP417 is closely related to that of both the erythromycin resistance plasmid pBFTM10 and the 5-Ni resistance plasmid pIP419 but not to that of the 5-Ni resistance plasmid pIP421.The dissemination of drug resistance determinants among bacteria of medical importance is currently a major problem for the prescription of efficient antibiotic regimens. This is particularly true for Bacteroides spp., a prevalent anaerobic bacterial genus causing human infections, since the majority of the strains are now frequently resistant to commonly used antibiotics. The resistance determinants of tetracycline (TET) and macrolides-lincosamides-streptogramin B (MLS), which were first described in 1979 (24, 41, 45), have been disseminated by specific efficient conjugal transfer systems. Conjugal genetic exchange of these resistance markers in Bacteroides spp. is now well documented (16,(29)(30)(31)(32). Various genetic elements have been shown to be involved, including (i) large conjugative plasmids like pBF4, a 41-kb plasmid from Bacteroides fragilis, or pBI136, an 80-kb plasmid from Bacteroides ovatus; (ii) small mobilizable plasmids like pBFTM10, a 15-kb plasmid from B. fragilis; and (iii) conjugative transposons (Tc r / Tc r Em r elements). Bacteroides conjugative transposons are large chromosomal self-transmissible elements, ranging in size from 65 to more than 150 kb, which can also drive the mobilization of other elements, such as small coresident plasmids, either in trans or in cis. Three distinct families have been described: the Tc r Em r DOT family that usually carries both tetQ and ermF genes but includes at least one cryptic element, XBU4422; the Tc r Em r 12256 element (also called Tn5030) that consists...

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“…A further reduction of the mating time to 1 h, with the addition of fresh antibodies every 15 min, still had no effect on the transfer frequency of pBF4. Macrina, 1993). Structural and molecular genetic studies defined a compound transposon carrying the ermF antibiotic-resistance gene on pBF4 (Rasmussen et al, 1986Shoemaker et al, 1986).…”

Section: Attempted Localization Of Bctamentioning

confidence: 99%

bctA: a novel pBF4 gene necessary for conjugal transfer in Bacteroides spp.

Morgan

Macrina

1997

Microbiology

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pBF4 is a 41 kb conjugative R-plasmid that confers MLS (macrolide-lincosamidestreptogramin B) resistance in Bademides spp. T o identify pBF4 genes governing conjugation, recombinational mutagenesis using a suicide vector carrying fragments of the pBF4 plasmid was employed. One of six independent insertion mutants of pBF4 isolated using this method was found to be conjugation-def icient. Nucleotide sequence analysis around the insertion site on this plasmid revealed a 2.8 kb ORF that encoded a putative 110 kDa protein.A corresponding protein was observed when a 12 kb DNA fragment containing this ORF was used to program an in vitm transcription-translation system. Both the ORF and the predicted protein were novel when compared to available database sequences. This gene was designated bctA (Baderaides -conjugal transfer). Polyclonal rabbit antibodies that recognized a sub-sequence polypeptide of BctA reacted with a 55 kDa protein in Western blot analysis using a total protein extract from Bademides fragilis containing pBF4. The protein was not present in a B. fragilis strain containing the conjugationdeficient insertion mutant of pBF4. The 55 kDa protein was associated with the membrane fraction of B. fragilis. Although the cellular and biochemical basis of bctA-promoted conjugation remains unknown, this work demonstrates the existence of a heretofore unrecognized gene in bacterial conjugation, and the mutagenesis system used provides the means to isolate and characterize other genes involved in conjugal transfer in Bademides spp.USA

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Conjugal Transfer in Anaerobic Bacteria

Cited by 9 publications

References 59 publications

Conjugative transposons: an unusual and diverse set of integrated gene transfer elements.

Conjugative transposons: an unusual and diverse set of integrated gene transfer elements.

Conjugal transfer of the 5-nitroimidazole resistance plasmid pIP417 from Bacteroides vulgatus BV-17: characterization and nucleotide sequence analysis of the mobilization region

bctA: a novel pBF4 gene necessary for conjugal transfer in Bacteroides spp.

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