Mobile genetic elements in the genus Bacteroides, and their mechanism(s) of dissemination

Nguyen, Mai Thi Thanh; Vedantam, Gayatri

doi:10.4161/mge.1.3.18448

Cited by 34 publications

(34 citation statements)

References 128 publications

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“…These human gut bacteria are known to have a very plastic genome and a plethora of autonomous and non-autonomous mobile elements that are transferred mostly by conjugation [14]. They also carry numerous DGRs that cluster in two separate clades according to the RT phylogeny (Figure 2).…”

Section: Resultsmentioning

confidence: 99%

Analysis of a comprehensive dataset of diversity generating retroelements generated by the program DiGReF

et al. 2012

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BackgroundDiversity Generating Retroelements (DGRs) are genetic cassettes that can introduce tremendous diversity into a short, defined region of the genome. They achieve hypermutation through replacement of the variable region with a strongly mutated cDNA copy generated by the element-encoded reverse transcriptase. In contrast to “selfish” retroelements such as group II introns and retrotransposons, DGRs impart an advantage to their host by increasing its adaptive potential. DGRs were discovered in a bacteriophage, but since then additional examples have been identified in some bacterial genomes.ResultsHere we present the program DiGReF that allowed us to comprehensively screen available databases for DGRs. We identified 155 DGRs which are found in all major classes of bacteria, though exhibiting sporadic distribution across species. Phylogenetic analysis and sequence comparison showed that DGRs move between genomes by associating with various mobile elements such as phages, transposons and plasmids. The DGR cassettes exhibit high flexibility in the arrangement of their components and easily acquire additional paralogous target genes. Surprisingly, the genomic data alone provide new insights into the molecular mechanism of DGRs. Most notably, our data suggest that the template RNA is transcribed separately from the rest of the element.ConclusionsDiGReF is a valuable tool to detect DGRs in genome data. Its output allows comprehensive analysis of various aspects of DGR biology, thus deepening our understanding of the role DGRs play in prokaryotic genome plasticity, from the global down to the molecular level.

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Section: Resultsmentioning

confidence: 99%

Analysis of a comprehensive dataset of diversity generating retroelements generated by the program DiGReF

et al. 2012

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“…Although rare, Bacteroides can also cause endocarditis, meningitis, and septic arthritis (15). Bacteroides infections are becoming increasingly difficult to treat due to the prevalence of antibiotic resistance among members of this genus, which makes Bacteroides infections a serious public health threat (18). The problem of increasing antibiotic resistance in this genus is illustrated by tetracycline (Tc), which used to be a frontline antibiotic used for the treatment of Bacteroides infections due to its broad spectrum, ease of use, low incidence of side effects, and cost (19).…”

Section: Introductionmentioning

confidence: 99%

Regulation of CTnDOT Conjugative Transfer Is a Complex and Highly Coordinated Series of Events

Waters

Salyers

2013

mBio

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CTnDOT is a 65-kb conjugative transposon that is found in Bacteroides spp., which are one of the more abundant members within the lower human gastrointestinal tract. CTnDOT encodes resistance to the antibiotics erythromycin and tetracycline (Tc). An interesting feature of CTnDOT is that exposure to low levels of Tc induces a cascade of events that ultimately results in CTnDOT conjugative transfer. However, Tc is apparently not a switch that activates transfer but rather a signal that appears to override a series of negative regulators that inhibit premature excision and transfer of CTnDOT. In this minireview, we summarize over 20 years of research that focused on elucidating the highly coordinated regulation of excision, mobilization, and transfer of CTnDOT.

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“…can be detrimental to the host if they escape the colon, causing opportunistic infections that may be difficult to treat. These infections may not respond well to antibiotic therapy due to the increasing prevalence of antibiotic resistance within Bacteroides, which is often linked to mobile genetic elements (3)(4)(5). One such element is CTnDOT, a 65-kb conjugative transposon that confers resistance to the antibiotics erythromycin (ermF) and tetracycline (tetQ).…”

mentioning

confidence: 99%

Tetracycline-Related Transcriptional Regulation of the CTnDOT Mobilization Region

2013

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CTnDOT is a 65-kb conjugative transposon (CTn) in Bacteroides spp. that confers resistance to the antibiotics erythromycin and tetracycline (Tc). Conjugative transfer of CTnDOT is regulated upon exposure of cells to Tc. In the absence of Tc, no transfer is detectable; however, a cascade of regulatory events results in the conjugative transfer of CTnDOT upon Tc induction. Previous studies addressing regulation of CTnDOT conjugative transfer focused primarily on the 13-kb transfer (tra) operon, which encodes the proteins required for assembly of the mating apparatus. We report here that the mob operon that encodes the relaxase and coupling proteins required for mobilization of CTnDOT are regulated at the transcriptional level upon Tc induction. The Xis2d and Exc excision proteins are required for the upregulation of mob transcription upon Tc induction, and yet a deletion of xis2c has no effect. We also show preliminary evidence suggesting that the integrase, IntDOT, may play a regulatory role, as pLYL72 transfer is not detectable when intDOT is provided in trans.

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Mobile genetic elements in the genus Bacteroides, and their mechanism(s) of dissemination

Cited by 34 publications

References 128 publications

Analysis of a comprehensive dataset of diversity generating retroelements generated by the program DiGReF

Analysis of a comprehensive dataset of diversity generating retroelements generated by the program DiGReF

Regulation of CTnDOT Conjugative Transfer Is a Complex and Highly Coordinated Series of Events

Tetracycline-Related Transcriptional Regulation of the CTnDOT Mobilization Region

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