Dataset Information

The Bacillus subtilis Conjugative Plasmid pLS20 Encodes Two Ribbon-Helix-Helix Type Auxiliary Relaxosome Proteins That Are Essential for Conjugation.

ABSTRACT: Bacterial conjugation is the process by which a conjugative element (CE) is transferred horizontally from a donor to a recipient cell via a connecting pore. One of the first steps in the conjugation process is the formation of a nucleoprotein complex at the origin of transfer (oriT), where one of the components of the nucleoprotein complex, the relaxase, introduces a site- and strand specific nick to initiate the transfer of a single DNA strand into the recipient cell. In most cases, the nucleoprotein complex involves, besides the relaxase, one or more additional proteins, named auxiliary proteins, which are encoded by the CE and/or the host. The conjugative plasmid pLS20 replicates in the Gram-positive Firmicute bacterium Bacillus subtilis. We have recently identified the relaxase gene and the oriT of pLS20, which are separated by a region of almost 1 kb. Here we show that this region contains two auxiliary genes that we name aux1LS20 and aux2LS20 , and which we show are essential for conjugation. Both Aux1LS20 and Aux2LS20 are predicted to contain a Ribbon-Helix-Helix DNA binding motif near their N-terminus. Analyses of the purified proteins show that Aux1LS20 and Aux2LS20 form tetramers and hexamers in solution, respectively, and that they both bind preferentially to oriTLS20 , although with different characteristics and specificities. In silico analyses revealed that genes encoding homologs of Aux1LS20 and/or Aux2LS20 are located upstream of almost 400 relaxase genes of the RelLS20 family (MOBL) of relaxases. Thus, Aux1LS20 and Aux2LS20 of pLS20 constitute the founding member of the first two families of auxiliary proteins described for CEs of Gram-positive origin.

SUBMITTER: Miguel-Arribas A

PROVIDER: S-EPMC5675868 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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The <i>Bacillus subtilis</i> Conjugative Plasmid pLS20 Encodes Two Ribbon-Helix-Helix Type Auxiliary Relaxosome Proteins That Are Essential for Conjugation.

Miguel-Arribas Andrés A Hao Jian-An JA Luque-Ortega Juan R JR Ramachandran Gayetri G Val-Calvo Jorge J Gago-Córdoba César C González-Álvarez Daniel D Abia David D Alfonso Carlos C Wu Ling J LJ Meijer Wilfried J J WJJ

Frontiers in microbiology 20171103

Bacterial conjugation is the process by which a conjugative element (CE) is transferred horizontally from a donor to a recipient cell via a connecting pore. One of the first steps in the conjugation process is the formation of a nucleoprotein complex at the origin of transfer (<i>oriT</i>), where one of the components of the nucleoprotein complex, the relaxase, introduces a site- and strand specific nick to initiate the transfer of a single DNA strand into the recipient cell. In most cases, the ...[more]

PMID: 29163424

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Project description:A major virulence factor in Clostridium sordellii-mediated infection is the toxin TcsL, which is encoded within a region of the genome called the pathogenicity locus (PaLoc). C. sordellii isolates carry the PaLoc on the pCS1 family of plasmids, of which there are four characterized members. Here, we determined the potential mobility of pCS1 plasmids and characterized a fifth unique pCS1 member. Using a derivative of the pCS1-1 plasmid from strain ATCC 9714 which had been marked with the ermB erythromycin resistance gene, conjugative transfer into a recipient C. sordellii isolate, R28058, was demonstrated. Bioinformatic analysis of pCS1-1 identified a novel conjugation gene cluster defined as the C. sordellii transfer (cst) locus. Interruption of genes within the cst locus resulted in loss of pCS1-1 transfer, which was restored upon complementation in trans These studies provided clear evidence that genes within the cst locus are essential for the conjugative transfer of pCS1-1. The cst locus is present on all pCS1 subtypes, and homologous loci were identified on toxin-encoding plasmids from Clostridium perfringens and Clostridium botulinum and also carried within genomes of Clostridium difficile isolates, indicating that it is a widespread clostridial conjugation locus. The results of this study have broad implications for the dissemination of toxin genes and, potentially, antibiotic resistance genes among members of a diverse range of clostridial pathogens, providing these microorganisms with a survival advantage within the infected host.IMPORTANCEC. sordellii is a bacterial pathogen that causes severe infections in humans and animals, with high mortality rates. While the pathogenesis of C. sordellii infections is not well understood, it is known that the toxin TcsL is an important virulence factor. Here, we have shown the ability of a plasmid carrying the tcsL gene to undergo conjugative transfer between distantly related strains of C. sordellii, which has far-reaching implications for the ability of C. sordellii to acquire the capacity to cause disease. Plasmids that carry tcsL encode a previously uncharacterized conjugation locus, and individual genes within this locus were shown to be required for conjugative transfer. Furthermore, homologues on toxin plasmids from other clostridial species were identified, indicating that this region represents a novel clostridial conjugation locus. The results of this study have broad implications for the dissemination of virulence genes among members of a diverse range of clostridial pathogens.

Dataset Information

The Bacillus subtilis Conjugative Plasmid pLS20 Encodes Two Ribbon-Helix-Helix Type Auxiliary Relaxosome Proteins That Are Essential for Conjugation.

Publications

The <i>Bacillus subtilis</i> Conjugative Plasmid pLS20 Encodes Two Ribbon-Helix-Helix Type Auxiliary Relaxosome Proteins That Are Essential for Conjugation.

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