AUTHOR=Faure Denis , Lang Julien 

TITLE=Functions and regulation of quorum-sensing in Agrobacterium tumefaciens

JOURNAL=Frontiers in Plant Science

VOLUME=5

YEAR=2014

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2014.00014

DOI=10.3389/fpls.2014.00014

ISSN=1664-462X

ABSTRACT=<p>In <italic>Agrobacterium tumefaciens</italic>, horizontal transfer and vegetative replication of oncogenic Ti plasmids involve a cell-to-cell communication process called quorum-sensing (QS). The determinants of the QS-system belong to the LuxR/LuxI class. The LuxI-like protein TraI synthesizes <italic>N</italic>-acyl-homoserine lactone molecules which act as diffusible QS-signals. Beyond a threshold concentration, these molecules bind and activate the LuxR-like transcriptional regulator TraR, thereby initiating the QS-regulatory pathway. For the last 20 years, <italic>A. tumefaciens</italic> has stood as a prominent model in the understanding of the LuxR/LuxI type of QS systems. A number of studies also unveiled features which are unique to <italic>A. tumefaciens</italic> QS, some of them being directly related to the phytopathogenic lifestyle of the bacteria. In this review, we will present the current knowledge of QS in <italic>A. tumefaciens</italic> at both the genetic and molecular levels. We will also describe how interactions with plant host modulate the QS pathway of <italic>A. tumefaciens</italic>, and discuss what could be the advantages for the agrobacteria to use such a tightly regulated QS-system to disseminate the Ti plasmids.</p>