Identification and characterization of the immunity repressor (ImmR) that controls the mobile genetic element ICEBs1 of Bacillus subtilis

Abstract

SummaryICEBs1 is a mobile genetic element found in the chromosome of Bacillus subtilis. Excision and transfer of ICEBs1 is regulated by the global DNA damage response and intercellular peptide signalling. We identified and characterized a repressor, ImmR (formerly YdcN), encoded by ICEBs1. ImmR represses transcription of genes required for excision and transfer, and both activates and represses its own transcription. ImmR regulates transcription within ICEBs1 by binding to several sites in the region of DNA that contains promoters for both immR and xis (encoding excisionase). In addition, we found that ImmR confers immunity from acquisition of additional copies of ICEBs1. ImmR-mediated regulation serves to keep a single copy of ICEBs1 stably maintained in the absence of induction, allows a rapid response to inducing signals, and helps limit acquisition of additional copies of ICEBs1.

Biological Diversity of Prokaryotic Type IV Secretion Systems

“…One particularly interesting ICE recently identified in B. subtilis, ICEBs1, efficiently transfers between cells in response to global DNA damage, and transfer among donor cell populations is also inhibited by a quorumsensing immunity system (13,14). Once the element excises from the chromosome, NicK relaxase catalyzes nicking at the oriT sequence in the absence of other factors (170,171).…”

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

“…MDNA3-0008-2014.f5 It is mediated by the integrase and triggered by the expression the RDF gene xis. Although int seems to be constitutively expressed, the expression of xis is repressed from its σ A -recognized promoter P xis and depends on a complex regulatory system described below (77,78).…”

“…The only well characterized cI-like regulator, ImmR, is encoded by ICEBs1 (Fig. 5) (78,87). ImmR regulates its own expression and represses the expression of the RDF Xis from P xis , thereby repressing the expression of the whole operon encoding the T4SS and DNA processing functions (78).…”

“…ImmR regulates its own expression and represses the expression of the RDF Xis from P xis , thereby repressing the expression of the whole operon encoding the T4SS and DNA processing functions (78). A constant intracellular level of ImmR protein is maintained by the dose-dependent regulation of ImmR on its own promoter, leading to its autorepression when the amount of intracellular ImmR is high (78). ImmR is associated with ImmA, a protease encoded by the same operon that allows the derepression of the mobility of ICEBs1 (Fig.…”

Fatores envolvidos com a mobilização de PAPI-1

“…Foi documentado que proteínas H-NS reprimem mais de 400 genes em Salmonella, sendo que aproximadamente 90% destes foram provavelmente adquiridos por transferência horizontal (Navarre, et al 2007). Em ICEBs1, encontrado em Bacillus subtilis, um membro da família das proteínas H-NS conhecida como ImmR, reprime os genes necessários para a transferência deste elemento para outras células bacterianas (Auchtung, et al 2007). Recentemente, foi demonstrado que um membro da família H-NS presente no plasmídeo R27 de Salmonella restringiu-se apenas em regular uma pequena quantidade de genes que foram provavelmente adquiridos por transferência horizontal, em comparação com as centenas de genes regulados pela H-NS codificada pelo cromossomo (Baños, et al 2009).…”