Sequential induction of three recombination directionality factors directs assembly of tripartite integrative and conjugative elements
MetadataShow full item record
Tripartite integrative and conjugative elements (ICE3) are a novel form of ICE that exist as three separate DNA regions integrated within the genomes of Mesorhizobium spp. Prior to conjugative transfer the three ICE3 regions of M. ciceri WSM1271 ICEMcSym1271 combine and excise to form a single circular element. This assembly requires three coordinated recombination events involving three site-specific recombinases IntS, IntG and IntM. Here, we demonstrate that three excisionases–or recombination directionality factors—RdfS, RdfG and RdfM are required for ICE3 excision. Transcriptome sequencing revealed that expression of ICE3 transfer and conjugation genes was induced by quorum sensing. Quorum sensing activated expression of rdfS, and in turn RdfS stimulated transcription of both rdfG and rdfM. Therefore, RdfS acts as a “master controller” of ICE3 assembly and excision. The dependence of all three excisive reactions on RdfS ensures that ICE3 excision occurs via a stepwise sequence of recombination events that avoids splitting the chromosome into a non-viable configuration. These discoveries expose a surprisingly simple control system guiding molecular assembly of these novel and complex mobile genetic elements and highlight the diverse and critical functions of excisionase proteins in control of horizontal gene transfer.
Showing items related by title, author, creator and subject.
Delineation of the integrase-attachment and origin-of-transfer regions of the symbiosis island ICEMlSymR7A.Ramsay, Joshua; Verdonk, Callum J; Sullivan, John T; Williman, Kate M; Nicholson, Leila; Bastholm, Tahlia R; Hynes, Michael F; Ronson, Clive W; Bond, Charles S (2019)Integrative and conjugative elements (ICEs) are chromosomally-integrated mobile genetic elements that excise from their host chromosome and transfer to other bacteria via conjugation. ICEMlSymR7A is the prototypical member ...
Ribosomal frameshifting and dual-target antiactivation restrict quorum-sensing-activated transfer of a mobile genetic elementRamsay, Joshua; Tester, L.; Major, A.; Sullivan, J.; Edgar, C.; Kleffmann, T.; Patterson-House, Jackson; Hall, D.; Tate, W.; Hynes, M.; Ronson, C. (2015)Symbiosis islands are integrative and conjugative mobile genetic elements that convert nonsymbiotic rhizobia into nitrogen-fixing symbionts of leguminous plants. Excision of the Mesorhizobium loti symbiosis island ICEMlSymR7A ...
Udo, Edet Ekpenyong (1991)Fifty three Staphylococcus aureus isolates were obtained from three centres, two hospitals and a private pathology laboratory, and studied for susceptibility to bacteriophages, resistance to antimicrobial agents and plasmid ...