Transcriptome analysis revealed that a quorum sensing system regulates the transfer of the pAt megaplasmid in Agrobacterium tumefaciens

Abstract

BackgroundAgrobacterium tumefaciens strain P4 is atypical, as the strain is not pathogenic and produces a for this species unusual quorum sensing signal, identified as N-(3-hydroxy-octanoyl)-homoserine lactone (3OH,C8-HSL).ResultsBy sequence analysis and cloning, a functional luxI-like gene, named cinI, has been identified on the At plasmid of A. tumefaciens strain P4. Insertion mutagenesis in the cinI gene and transcriptome analyses permitted the identification of 32 cinI-regulated genes in this strain, most of them encoding proteins responsible for the conjugative transfer of pAtP4. Among these genes were the avhB genes that encode a type 4 secretion system (T4SS) involved in the formation of the conjugation apparatus, the tra genes that encode the DNA transfer and replication (Dtr) machinery and cinI and two luxR orthologs. These last two genes, cinR and cinX, exhibit an unusual organization, with the cinI gene surrounded by the two luxR orthologs. Conjugation experiments confirmed that the conjugative transfer of pAtP4 is regulated by 3OH,C8-HSL. Root colonization experiments indicated that the quorum sensing regulation of the conjugation of the pAtP4 does not confer a gain or a loss of fitness to the bacterial host in the tomato plant rhizosphere.ConclusionThis work is the first identification of the occurrence of a quorum sensing regulation of the pAt conjugation phenomenon in Agrobacterium.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-3007-5) contains supplementary material, which is available to authorized users.

Regulation of conjugative transfer of plasmids and integrative conjugative elements

“…Bioinformatic data have shown the presence of rctA and rctB homologues in the A. tumefaciens pAT plasmid, and recent transcriptomic data suggest that, at least in the pAT plasmid of strain P4, the regulation by RctA-RctB is under QS control (Mhedbi-Hajri et al, 2016;Nogales et al, 2013). A different regulatory system has been described for pESI from Salmonella enterica sv infantis (Aviv et al, 2016).…”

Transcriptional response of Nautella italica R11 towards its macroalgal host uncovers new mechanisms of host–pathogen interaction

“…Therefore, despite finding no difference in attachment or biofilm formation under laboratory conditions (Figure 2), RaiR may nevertheless play a role (via the regulation of a Atse homolog) in the initial colonization of D. pulchra. This possibility is further supported by findings that Atse expression is positively controlled by QS and is important for virulence in the plant pathogen A. tumefaciens (Matthysse, Yarnall, Boles, & McMahan, 2000;Mhedbi-Hajri et al, 2016). Previous proteomic studies indicated that the N. italica R11 gene regulator…”

Transcriptome Profiling Reveals the EanI/R Quorum Sensing Regulon in Pantoea Ananatis LMG 2665T

“…A recent transcriptome analysis study showed that QS regulates conjugative transfer in Agrobacterium tumefaciens [ 46 ]. Transcriptome profiling showed that the EanI/R up regulates a conjugal transfer gene traF , a gene important for plasmid transfer in P. ananatis LMG 2665 T ( Table 3 ).…”