Phosphorylation of the VirG protein of Agrobacterium tumefaciens by the autophosphorylated VirA protein: essential role in biological activity of VirG

Jin, Shouguang; Prusti, Rabi K.; Roitsch, Thomas; Ankenbauer, Robert G.; Nester, Eugene W.

doi:10.1128/jb.172.9.4945-4950.1990

Cited by 176 publications

(92 citation statements)

References 37 publications

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“…as long as several generation times of the organism (for OmpR and VirG [65,66]; for review see [14]). In combination with the amplification of the signalling machinery, which is observable in some signal transfer pathways (see below), the extremely long lifetime of a number of the phosphorylated response regulators provides the cell with some sort of memory.…”

Section: Monomers Versus Dimers and The Mechanism Of Transmembrane Simentioning

confidence: 99%

Signal transduction in bacteria: phospho-neural network(s) in Escherichia coli?

Hellingwerf

1995

FEMS Microbiology Reviews

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The molecular basis of many forms of signal transfer in living organisms is provided via the transient phosphorylation of regulatory proteins by transfer of phosphoryl groups between these proteins. The dominant form of signal transduction in prokaryotic microorganisms proceeds via so-called two-component regulatory systems. These systems constitute phosphoryl transfer pathways, consisting of two or more components. Most of these pathways are linear, but some converge and some are divergent. The molecular properties of some of the well-characterised representatives of two-component systems comply with the requirements to be put upon the elements of a neural network: they function as logical operators and show the phenomenon of autoamplification. Because there are many phosphoryl transfer pathways in parallel and because there also appears to be cross-talk between these pathways, the total of all two-component regulatory systems in a single prokaryotic cell may show the typical characteristics of a 'phospho-neural network'. This may well lead to signal amplification, associative responses and memory effects, characteristics which are typical for neural networks. One of the main challenges in molecular microbial physiology is to determine the extent of the connectivity of the constituting elements of this presumed 'phospho-neural network', and to outline the extent of intelligence-like behaviour this network can generate. Escherichia coli is the organism of choice for this characterization.

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Section: Monomers Versus Dimers and The Mechanism Of Transmembrane Simentioning

confidence: 99%

Signal transduction in bacteria: phospho-neural network(s) in Escherichia coli?

Hellingwerf

1995

FEMS Microbiology Reviews

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“…Autophosphorylation in the C-terminal cytoplasmic domain of VirA (9, 10) and subsequent phosphate transfer to the transcriptional regulator, VirG (11), have been demonstrated in vitro and together constitute a phenol-activated signaling pathway. At least two other environmental stimuli, acidic pH and monosaccharides, act synergistically with the phenolic signals to activate vir gene expression (2).…”

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confidence: 99%

Mechanism of activation of Agrobacterium virulence genes: identification of phenol-binding proteins.

Lee

Dudley

Hess

et al. 1992

Proc. Natl. Acad. Sci. U.S.A.

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Agrobacterium tumefaciens initiates the expression of pathogenic genes (vir genes) in response to hostderived phenolic signals through a two-component regulatory system consisting of VirA and VirG. a-Bromoacetosyringone (ASBr) was developed as an inhibitor of this induction process and found to be a specific and irreversible inhibitor of vir gene induction in this pathogen. Formal replacement of one of the methoxy groups of ASBr with Iodine gave an equally effective inhibitor that could carry an 'mI label. We report here that the resulting radiolabeled inhibitor does not react with the sensory component of this system, VirA, either in vivo or in vitro. Rather, two small proteins, p1O and p2l, bind labeled inhibitor in vivo in a time period that is consistent with the exposure time required for the inhibition of vir gene expression. Labeling to these proteins was protected by preexposure to ASBr but not by a-bromo-3,5-dlmethoxyacetophenone, a compound of comparable chemical reactivity but previously shown not to inhibit vir gene expression. Our findings suggest that proteins that are not tumor-inducing plasmid-encoded mediate vir gene activation in a step prior to the VirA/VirG two-component regulatory system. Agrobacterium tumefaciens is the causative agent of crown gall tumors, a neoplastic disease of many dicotyledonous plants (1,2). A small oncogenic segment [transferred DNA (T-DNA)] of the tumor-inducing (Ti) plasmid harbored by these bacteria is transferred to the host cell, inducing the disease state. Many ofthe genes of the virulence regulon (vir) of the Ti plasmid required for this transfer are only expressed in the presence of host-derived phenolic compounds (3), one of which has been implicated in the control of division in the host cell (4-6).Sequence homology of two constitutively expressed genes of the vir regulon, virA and virG, with what now appears to be a large family of procaryotic two-component regulatory proteins (7) led to the proposal that these proteins served as the sensor/response elements controlling vir expression (8).This model predicts that VirA would interact with the phenolic inducer as the initiation step. Autophosphorylation in the C-terminal cytoplasmic domain of VirA (9, 10) and subsequent phosphate transfer to the transcriptional regulator, VirG (11), have been demonstrated in vitro and together constitute a phenol-activated signaling pathway. At least two other environmental stimuli, acidic pH and monosaccharides, act synergistically with the phenolic signals to activate vir gene expression (2).The dissection of the structures of these phenolic inducers has provided sufficient insight for the development of specific, irreversible inhibitors of vir gene expression (12). We now provide evidence that these inhibitors do not interact directly with VirA but rather with two other proteins, p10 and p21. We propose that these chromosomally encoded proteins modulate the signal transduction pathway prior to the autophosphorylation of VirA. MATERIALS AND METHODS Syntheses. a-Bro...

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“…These systems have been found in over 20 different functional contexts including chemotaxis, nitrogen and phosphate regula- Deutscher and Engelmann, 1984Deutscher et al, 1984Mimura et al, 1987Deutscher and Engelmann, 1984Waygood et al, 1986Dobrova et al, 1990Hong et al, 1991Deutscher and Saier, 1988Skorko, 1984Sykora and Charles, 1991Mann et al, 1991Schuster et al, 1984Sanders et al. 1989Karr et al, 1989Nixon et al. 1986 tion, porin gene expression, sporulation, competence, virulence, alginate production, and exoprotein synthesis, among others.…”

Section: Protel N-h Lstl Dine Ki Nasesmentioning

confidence: 99%

ATP‐dependent protein kinases in bacteria

Cozzone

1993

J of Cellular Biochemistry

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Protein phosphorylation has been shown to occur in over fifty different bacterial species and, therefore, seems to be a universal device among prokaryotes. Most of the protein kinases responsible for this modification of proteins share the common property of using adenosine triphosphate as phosphoryl donnor. However, they differ from one another in a number of structural and functional aspects. Namely, they exhibit a varying acceptor amino acid specificity and can be classified, on this basis, in three main groups: protein-histidine kinases, protein-serine/threonine kinases and protein-tyrosine kinases.

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Phosphorylation of the VirG protein of Agrobacterium tumefaciens by the autophosphorylated VirA protein: essential role in biological activity of VirG

Cited by 176 publications

References 37 publications

Signal transduction in bacteria: phospho-neural network(s) in Escherichia coli?

Signal transduction in bacteria: phospho-neural network(s) in Escherichia coli?

Mechanism of activation of Agrobacterium virulence genes: identification of phenol-binding proteins.

ATP‐dependent protein kinases in bacteria

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