Concerted transfer of the virulence Ti plasmid and companion At plasmid in the Agrobacterium tumefaciens‐induced plant tumour. Issue 6 (31st October 2013)

• Record Type: Journal Article
• Authors: Lang, Julien; Planamente, Sara; Mondy, Samuel; Dessaux, Yves; Moréra, Solange; Faure, Denis
• Is Part Of: Molecular microbiology. Volume 90:Issue 6(2013)
• Page Start: 1178
• Page End: 1189
• Publication Date: 2013-10-31
• Subjects: Molecular microbiology -- Periodicals; 572.829
• DOI: 10.1111/mmi.12423
• Languages: English
• ISSNs: 0950-382X

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p>The plant pathogen <italic>Agrobacterium tumefaciens</italic> C58 harbours three independent type IV secretion (T4SS) machineries. T4SS<sub>T‐DNA</sub> promotes the transfer of the T‐DNA to host plant cells, provoking tumour development and accumulation of opines such as nopaline and agrocinopines. T4SS<sub>pTi</sub> and T4SS<sub>pAt</sub> control the bacterial conjugation of the Ti and At plasmids respectively. Expression of T4SS<sub>pTi</sub> is controlled by the agrocinopine‐responsive transcriptional repressor AccR. In this work, we compared the genome‐wide transcriptional profile of the wild‐type <italic>A. tumefaciens</italic> strain C58 with that of its <italic>accR</italic> KO‐mutant to delineate the AccR regulon. In addition to the genes that encode agrocinopine catabolism and T4SS<sub>pTi</sub>, we found that AccR also regulated genes coding for nopaline catabolism and T4SS<sub>pAt</sub>. Further opine detection and conjugation assays confirmed the enhancement of nopaline consumption and At plasmid conjugation frequency in <italic>accR</italic>. Moreover, co‐regulation of the T4SS<sub>pTi</sub> and T4SS<sub>pAt</sub> correlated with the co‐transfer of the At and Ti plasmids both <italic>in vitro</italic> and in plant tumours. Finally, unlike T4SS<sub>pTi</sub>, T4SS<sub>pAt</sub> activation does not require quorum‐sensing. Overall this study highlights the regulatory interplays between opines, At and Ti plasmids that contribute to a concerted dissemination of the two replicons in bacterial populations colonizing the plant tumour.</p> </abstract>