A host factor absent from <i>Lactococcus lactis</i> subspecies <i>lactis</i> MG1363 is required for conjugative transposition

Bringel, Françoise; Alstine, G L Van; Scott, June R.

doi:10.1111/j.1365-2958.1991.tb01858.x

Cited by 31 publications

(21 citation statements)

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“…On one hand, ImmR was shown to bind diverse loci in the chromosome of B. subtilis, which could have a significant impact on host gene expression, and consequently on the fitness of the organism (78). On the other hand, several studies have reported the implication of host factors in the modulation of ICE dynamics, in both Grampositive and Gram-negative bacteria (48,90,91). At least three host factors are known to influence ICEBs1 mobility.…”

Section: Immr/imma As a Central Regulatory System Of Icebs1mentioning

confidence: 99%

Biology of Three ICE Families: SXT/R391, ICE Bs1 , and ICE St1 /ICE St3

Carraro

Burrus

2014

Microbiol Spectr

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Integrative and Conjugative Elements (ICEs) are bacterial mobile genetic elements that play a key role in bacterial genomes dynamics and evolution. ICEs are widely distributed among virtually all bacterial genera. Recent extensive studies have unraveled their high diversity and complexity. The present review depicts the general conserved features of ICEs and describes more precisely three major families of ICEs that have been extensively studied in the past decade for their biology, their evolution and their impact on genomes dynamics. First, the large SXT/R391 family of ICEs disseminates antibiotic resistance genes and drives the exchange of mobilizable genomic islands (MGIs) between many enteric pathogens such as Vibrio cholerae. Second, ICEBs1 of Bacillus subtilis is the most well understood ICE of Gram-positive bacteria, notably regarding the regulation of its dissemination and its initially unforeseen extrachromosomal replication, which could be a common feature of ICEs of both Gram-positive and Gram-negative bacteria. Finally, ICESt1 and ICESt3 of Streptococcus thermophilus are the prototypes of a large family of ICEs widely distributed among various streptococci. These ICEs carry an original regulation module that associates regulators related to those of both SXT/R391 and ICEBs1. Study of ICESt1 and ICESt3 uncovered the cis-mobilization of related genomic islands (CIMEs) by a mechanism called accretion-mobilization, which likely represents a paradigm for the evolution of many ICEs and genomic islands. These three major families of ICEs give a glimpse about ICEs dynamics and their high impact on bacterial adaptation.

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Section: Immr/imma As a Central Regulatory System Of Icebs1mentioning

confidence: 99%

Biology of Three ICE Families: SXT/R391, ICE Bs1 , and ICE St1 /ICE St3

Carraro

Burrus

2014

Microbiol Spectr

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“…Bacterial hosts, such as Lactococcus lactis, in which Tn916 cannot excise, are unable to promote conjugative transposition (Bringel et al, 1991). Thus, in addition to their transfer functions, transfer of this class of elements requires transposon-encoded excision and integration functions.…”

Section: Introductionmentioning

confidence: 99%

Circularization of Tn916 is required for expression of the transposon‐encoded transfer functions: characterization of long tetracycline‐inducible transcripts reading through the attachment site

Celli

Trieu‐Cuot

1998

Molecular Microbiology

153

129

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SummaryA detailed transcriptional analysis of the conjugative transposon Tn916 was carried out, which revealed that transcription of the transfer functions requires excision of the element and dramatically increases in the presence of tetracycline. The key components of this regulatory system are two contiguous transposon-borne genes, orf7 and orf8, located downstream from and having the same polarity of transcription as the tetracycline resistance determinant tetM. The gene orf7 encodes a 140-amino-acid (aa) protein exhibiting limited homology with F of Bacillus subtilis, whereas orf8 encodes a 76-aa peptide that does not share any sequence homology with any cognate proteins. In the presence of tetracycline, an attenuation mechanism enables the transcription of orf7 and orf8 from the tetM promoter. The resulting increased synthesis of ORF7 and ORF8 activates the promoter P orf7 located upstream from orf7, which then directs the expression of the transfer functions in the transposon circular intermediate through long transcripts encompassing the attachment site. The apparently non-regulated promoter P xis located upstream of the excisionase encoding gene xis could also participate in the expression of the tra genes. We also demonstrate that Tn916 carries another regulated promoter, P orf9 , which directs transcription of a single gene, orf9, located downstream from and transcribed counterclockwise to tetM. This gene encodes a 117-aa putative transcriptional repressor, but the exact role of this protein in the mobility of Tn916, as well as the regulation of its expression, remains to be elucidated. Our results constitute the molecular basis for the observation that tetracycline increased the transfer frequency of this type of element.

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“…lactis (herein referred to as L. lactis) MG1363. In this gram-positive organism, Tn916 and Tn919 do not excise (3). Although it can act as a recipient for conjugative transposition from another genus, L. lactis MG1363 cannot donate conjugative transposons in plate matings with Bacillus subtilis, Enterococcus faecalis, or Streptococcus pyogenes.…”

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confidence: 99%