Transcription in vitro promoted by the Agrobacterium VirG protein

Abstract

Expression of the virulence genes (vir) on the hairy-root-inducing plasmid pRiA4 is induced by plant signals in Agrobucterium cells through a two-component regulatory system, the VirA-VirG system. We constructed an in vitro transcription system that consisted of the purified VirG protein and the Agrobacterium RNA polymerase holoenzyme. Both versions of VirG, the non-phosphorylated form and the VirA-phosphorylated form, were active but showed different patterns of the pa-dependency for transcriptional activation.

Linker insertion scanning of regA, an activator of exotoxin A production in Pseudomonas aeruginosa

“…A final piece of evidence supporting the identity of a transcriptional activation domain in RegA similar to those of ToxR, VirG and OmpR is that all of these regulators, with the exception of ToxR, have been shown to promote transcription through an association with RNAP holoenzyme (Slauch et al, 1991;Endoh et al, 1993;Tsuzuki et al, 1994;Walker et al, 1994). VirG has been demonstrated to promote in vitro transcription of vir -regulated genes in conjunction with the Agrobacterium tumefaciens RNAP holoenzyme (Endoh et al, 1993). Similarly, RegA can promote in vitro transcription of toxA in association with P. aeruginosa RNAP holoenzyme (Walker et al, 1994).…”