Details

Autor(en) / Beteiligte

• Ramsay, Joshua P
• Bastholm, Tahlia R
• Verdonk, Callum J
• Tambalo, Dinah D
• Sullivan, John T
• Harold, Liam K
• Panganiban, Beatrice A
• Colombi, Elena
• Perry, Benjamin J
• Jowsey, William
• Morris, Calum
• Hynes, Michael F
• Bond, Charles S
• Cameron, Andrew D S
• Yost, Christopher K
• Ronson, Clive W

Titel

An epigenetic switch activates bacterial quorum sensing and horizontal transfer of an integrative and conjugative element

Ist Teil von

• Nucleic acids research, 2022-01, Vol.50 (2), p.975-988

Ort / Verlag

England

Erscheinungsjahr

2022

Quelle

MEDLINE

Beschreibungen/Notizen

• Horizontal transfer of the integrative and conjugative element ICEMlSymR7A converts non-symbiotic Mesorhizobium spp. into nitrogen-fixing legume symbionts. Here, we discover subpopulations of Mesorhizobium japonicum R7A become epigenetically primed for quorum-sensing (QS) and QS-activated horizontal transfer. Isolated populations in this state termed R7A* maintained these phenotypes in laboratory culture but did not transfer the R7A* state to recipients of ICEMlSymR7A following conjugation. We previously demonstrated ICEMlSymR7A transfer and QS are repressed by the antiactivator QseM in R7A populations and that the adjacently-coded DNA-binding protein QseC represses qseM transcription. Here RNA-sequencing revealed qseM expression was repressed in R7A* cells and that RNA antisense to qseC was abundant in R7A but not R7A*. Deletion of the antisense-qseC promoter converted cells into an R7A*-like state. An adjacently coded QseC2 protein bound two operator sites and repressed antisense-qseC transcription. Plasmid overexpression of QseC2 stimulated the R7A* state, which persisted following curing of this plasmid. The epigenetic maintenance of the R7A* state required ICEMlSymR7A-encoded copies of both qseC and qseC2. Therefore, QseC and QseC2, together with their DNA-binding sites and overlapping promoters, form a stable epigenetic switch that establishes binary control over qseM transcription and primes a subpopulation of R7A cells for QS and horizontal transfer.