Proteomic analysis of Agrobacterium tumefaciens response to the vir gene inducer acetosyringone

Abstract

Agrobacterium tumefaciens causes crown gall disease in a wide range of plants by transforming plants through the transfer and integration of its transferred DNA (T-DNA) into the host genome. In the present study, we used two-dimensional gel electrophoresis to examine the protein expression profiles of A. tumefaciens in response to the phenolic compound acetosyringone (AS), a known plant-released virulence (vir) gene inducer. Using mass spectrometry, we identified 11 proteins consisting of 9 known AS-induced Vir proteins and 2 newly discovered AS-induced proteins, an unknown protein Y4mC (Atu6162) and a small heat shock protein HspL (Atu3887). Further expression analysis revealed that the AS-induced expression of Y4mC and HspL is regulated by the VirA/VirG two-component system. This report presents the first proteomics study successfully identifying both known and new AS-induced proteins that are implicated in Agrobacterium virulence.

Agrobacterium in the Genomics Age

“…Although incubation with root segments induced ChvE, AttK, and AttM (all proteins involved in virulence), their experiments detected no induced Ti-plasmid-encoded virulence proteins. Because, for example, VirE2 is a major virulence protein induced by phenolic molecules such as AS (Engstrom et al, 1987;Lai et al, 2006), the results of this study indicate either that vir gene induction did not efficiently occur or that it occurred in only a small percentage of the bacteria.…”

“…More recently, Lai et al (2006) investigated Agrobacterium proteins induced by the phenolic vir regulon inducer AS. Using two-dimensional gel electrophoresis coupled with mass spectrometry, they identified 11 ASinduced proteins.…”

Transfer and expression of the rabbit defensin NP-1 gene in lettuce (Lactuca sativa)

“…Xu et al (1988) first demonstrated that the excitation and efficient expression of the virulence (Vir) gene, which is necessary for the Ti plasmid of the Agrobacterium transfer into the host cell, was activated by AS trauma-induced molecules. Lai et al (2006) identified 11 AS-induced proteins, which were implicated in Agrobacterium virulence. Therefore, 100 mM AS was added in this experiment.…”

The Small Heat-shock Protein HspL Is a VirB8 Chaperone Promoting Type IV Secretion-mediated DNA Transfer

“…HspL Co-fractionates with VirB Complexes and Interacts with VirB8, a Key T4SS Assembly Factor-HspL is predicted to be a soluble protein without signal peptide or transmembrane domain (23), and therefore, its co-fractionation with membranes may be due to its association with membrane-associated VirB protein complexes. To assess this possibility, we extracted membrane proteins with the mild detergent DDM and then size-fractionated the DDMextracted proteins by SEC (Fig.…”

“…Multiple ␣-Hsp genes are present in rhizobial bacteria (19 -21) including A. tumefaciens containing at least four members of ␣-Hsp genes (hspC; hspL; hspAT1; hspAT2) (22). The latter three were induced by heat shock (22), whereas only hspL was up-regulated by the virulence gene inducer acetosyringone (AS) (18,23).…”