Regulation of Horizontal Gene Transfer in
            <i>Bacillus subtilis</i>
            by Activation of a Conserved Site-Specific Protease

Bose, Baundauna; Grossman, Alan D.

doi:10.1128/jb.01143-10

Cited by 56 publications

(69 citation statements)

References 17 publications

(24 reference statements)

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“…5) (87). Activated by the SOS response via an unknown mechanism, ImmA directly interacts with ImmR and cleaves it site specifically (86,87). Cleavage of ImmR by ImmA could result from the stimulation of ImmA proteolytic activity but also from its stabilization (86).…”

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

confidence: 99%

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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%

“…ICEBs1 is tightly regulated by the central ICE-encoded regulatory system ImmR/ImmA which is itself regulated by the host SOS response and quorum sensing (75,77,86).…”

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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“…ICEBs1 contains approximately two dozen open reading frames (ORFs), many of which have been characterized previously for their roles in regulation, DNA processing, DNA replication, and conjugation ( Fig. 1a) (9,(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28). ICEBs1 normally resides stably integrated in trnS-leu2, the gene for a leucine tRNA, unless its major operon is derepressed (20).…”

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confidence: 99%

Critical Components of the Conjugation Machinery of the Integrative and Conjugative Element ICE Bs1 of Bacillus subtilis

et al. 2015

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Conjugation, or mating, plays a profound role in bacterial evolution by spreading genes that allow bacteria to adapt to and colonize new niches. ICEBs1, an integrative and conjugative element of Bacillus subtilis, can transfer itself and mobilize resident plasmids. DNA transfer is mediated by a type IV secretion system (T4SS). Characterized components of the ICEBs1 T4SS include the conserved VirB4-like ATPase ConE, the bifunctional cell wall hydrolase CwlT, and the presumed VirD4-like coupling protein ConQ. A fusion of ConE to green fluorescent protein (GFP) localizes to the membrane preferentially at the cell poles. One or more ICEBs1 proteins are required for ConE's localization at the membrane, as ConE lacks predicted transmembrane segments and ConE-GFP is found dispersed throughout the cytoplasm in cells lacking ICEBs1. Here, we analyzed five ICEBs1 genes to determine if they are required for DNA transfer and/or ConE-GFP localization. We found that conB, conC, conD, and conG, but not yddF, are required for both ICEBs1 transfer and plasmid mobilization. All four required genes encode predicted integral membrane proteins. conB and, to some extent, conD were required for localization of ConE-GFP to the membrane. Using an adenylate cyclase-based bacterial two-hybrid system, we found that ConE interacts with ConB. We propose a model in which the ICEBs1 conjugation machinery is composed of ConB, ConC, ConD, ConE, ConG, CwlT, ConQ, and possibly other ICEBs1 proteins, and that ConB interacts with ConE, helping to recruit and/or maintain ConE at the membrane. IMPORTANCEConjugation is a major form of horizontal gene transfer and has played a profound role in bacterial evolution by moving genes, including those involved in antibiotic resistance, metabolism, symbiosis, and infectious disease. During conjugation, DNA is transferred from cell to cell through the conjugation machinery, a type of secretion system. Relatively little is known about the conjugation machinery of Gram-positive bacteria. Here, we analyzed five genes of the integrative and conjugative element ICEBs1 of Bacillus subtilis. Our research identifies four new components of the ICEBs1 conjugation machinery (ConB, ConC, ConD, and ConG) and shows an interaction between ConB and ConE that is required for ConE to associate with the cell membrane. Conjugation is a major form of horizontal gene transfer and plays a profound role in bacterial evolution and the acquisition of new traits (1-3). Conjugation can spread antibiotic resistance and disseminate genes involved in symbiosis, degradation of pollutants, metabolism, and pathogenesis. Conjugative elements encode specialized DNA translocation channels classified as type IV secretion systems (T4SSs) (4-7). T4SSs are composed of many interacting proteins that span the envelope of the donor cell. In addition to transferring the conjugative DNA element, the conjugation machinery also can mobilize resident plasmids or other DNA elements that do not encode their own machinery.There is a rich body of mechanis...

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“…The members of the ICESt1/ICESt3 family carry closely related conjugation modules found in various streptococci and harbour a peculiar regulation module. This module encodes two regulatory systems related to lambdoid prophage cI repressor (Beaber et al, 2004) and related to ImmA/ImmR regulatory systems (Bose & Grossman, 2011), suggesting a particularly complex regulation (Carraro & Burrus, 2014). Exposure of S. thermophilus to the DNA-damaging agent mitomycin C was found to promote not only excision and transfer of ICESt3 (Bellanger et al, 2009;Carraro et al, 2011), but also its adoption of a multicopy state, suggesting its capacity to replicate (Carraro et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Plasmid-like replication of a minimal streptococcal integrative and conjugative element

et al. 2016

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Integrative and conjugative elements (ICEs) are mobile genetic elements encoding their own excision from a replicon of their bacterial host, transfer by conjugation to a recipient bacterium and reintegration for maintenance. The conjugation, recombination and regulation modules of ICEs of the ICESt3 family are grouped together in a region called the ICE 'core region'. In addition to this core region, elements belonging to this family carry a highly variable region including cargo genes that could be involved in bacterial adaptation or in the maintenance of the element. Although ICEs are a major class of mobile elements through bacterial genomes, the functionality of an element encoding only its excision, transfer, integration and regulation has never been demonstrated experimentally. We engineered MiniICESt3, an artificial ICE derived from ICESt3, devoid of its cargo genes and thus only harbouring the core region. The functionality of this minimal element was assessed. MiniICESt3 was found to be able to excise at a rate of 3.1 %, transfer with a frequency of 1.0610 25 transconjugants per donor cell and stably maintain by site-specific integration into the 39 end of the fda gene, the same as ICESt3. Furthermore, MiniICESt3 was found in ,10 copies per chromosome, this multicopy state likely contributing to its stability for .100 generations even in the absence of selection. Therefore, although ICEs were primarily assumed to only replicate along with the chromosome, our results uncovered extrachromosomal rolling-circle replicating plasmid-like forms of MiniICESt3.

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Regulation of Horizontal Gene Transfer in Bacillus subtilis by Activation of a Conserved Site-Specific Protease

Cited by 56 publications

References 17 publications

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

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

Critical Components of the Conjugation Machinery of the Integrative and Conjugative Element ICE Bs1 of Bacillus subtilis

Plasmid-like replication of a minimal streptococcal integrative and conjugative element

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