RosR is a transcriptional regulator important for determining cell-surface
characteristics and nodulation competitiveness in Rhizobium etli CE3, We id
entified a 15-kb region that contains genes with similarity to members of t
he virB, virC, virG, and virE operons of Agrobacterium tumefaciens and demo
nstrated that RosR directly regulates one operon in this region. These gene
s were located on plasmid pa of R. etli CE3, which is self-transmissible be
tween R. etli and A. tumefaciens.