A chromosomal Agrobacterium tumefaciens gene required for effective plant signal transduction

Huang, Meei‐Li; Cangelosi, Gerard A.; Halperin, Walter; Nester, Eugene W.

doi:10.1128/jb.172.4.1814-1822.1990

Cited by 114 publications

(83 citation statements)

References 51 publications

(43 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Putative chvE mutants were characterized by examining their ability to be complemented for pathogenicity on tomato plants by a strategy already developed for virA and virG mutants (see above). The clones used in this complementation analysis contained the chromosomal chvE region from strain C58, either intact in pMWH146 or with chvE inactivated by a transposon insertion in pMWH102 (11).…”

Section: Methodsmentioning

confidence: 99%

“…Conceivably, nonpathogenic mutants produced by A. tumefaciens in association with the host plant could be altered either in the vir or T region of the Ti plasmid or in the chromosome. Chromosomal genes that are required for efficient plant transformation include chvE, which encodes a protein that potentiates the effect of plant phenolic compounds on vir gene induction (11).…”

mentioning

confidence: 99%

See 1 more Smart Citation

Genetic analysis of nonpathogenic Agrobacterium tumefaciens mutants arising in crown gall tumors

et al. 1995

View full text Add to dashboard Cite

Little is known about the effect of the host on the genetic stability of bacterial plant pathogens. Crown gall, a plant disease caused by Agrobacterium tumefaciens, may represent a useful model to study this effect. Indeed, our previous observations on the natural occurrence and origin of nonpathogenic agrobacteria suggest that the host plant might induce loss of pathogenicity in populations of A. tumefaciens. Here we report that five different A. tumefaciens strains initially isolated from apple tumors produced up to 99% nonpathogenic mutants following their reintroduction into axenic apple plants. Two of these five strains were also found to produce mutants on pear and/or blackberry plants. Generally, the mutants of the apple isolate D10B/87 were altered in the tumor-inducing plasmid, harboring either deletions in this plasmid or point mutations in the regulatory virulence gene virG. Most of the mutants originating from the same tumor appeared to be of clonal origin, implying that the host plants influenced agrobacterial populations by favoring growth of nonpathogenic mutants over that of wild-type cells. This hypothesis was confirmed by coinoculation of apple rootstocks with strain D10B/87 and a nonpathogenic mutant.The virulence (vir) and transferred (T) regions of Agrobacterium tumefaciens Ti plasmids contain genes directly involved in plant transformation. Expression of the vir genes by the bacterium is induced through the action of the virA-virG twocomponent regulatory system in response to plant phenolic compounds such as acetosyringone. The T-DNA, produced from the T region at the direction of the vir genes, becomes integrated into plant chromosomal DNA, where it determines the synthesis of plant growth hormones responsible for crown gall tumor development. The T-DNA also confers on tumor cells the capacity to produce unusual metabolites called opines. One of these opines, nopaline, is synthesized through the reductive condensation of arginine and ␣-ketoglutaric acid. Other Ti plasmid-encoded genes, which are not transferred to plant cells, enable the bacterial pathogen to utilize opines for growth and tumor colonization (for reviews, see references 5, 6, and 20). In spite of the enhanced colonization potential associated with expression of the opine catabolic genes, pathogenic Agrobacterium strains are difficult to recover from certain types of tumors in which nonpathogenic, opine-utilizing agrobacteria often prevail (4, 14). To account for the frequent occurrence of nonpathogenic agrobacteria, it is proposed here that some plant infections with A. tumefaciens result in the modification of the bacterial genome. Conceivably, nonpathogenic mutants produced by A. tumefaciens in association with the host plant could be altered either in the vir or T region of the Ti plasmid or in the chromosome. Chromosomal genes that are required for efficient plant transformation include chvE, which encodes a protein that potentiates the effect of plant phenolic compounds on vir gene induction (11).Our recent observatio...

show abstract

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

Genetic analysis of nonpathogenic Agrobacterium tumefaciens mutants arising in crown gall tumors

et al. 1995

View full text Add to dashboard Cite

show abstract

“…Wild-type A. tumefaciens strain A723 (C58 chromosome, pTiB6806) and its derivatives A1059 (chvE::TnS), A1068 (chvE::TnS), and A1030 (virA::TnS) have been described (12,15). Wild-type strain A348 (C58 chromosome, pTiA6NC) (16) and its derivatives A348-MX1 (chvE::TnS) (12) and A348-MX226 (virA::Tn3-HoHol) (17) were substituted for A723 and its derivatives when indicated.…”

Section: Methodsmentioning

confidence: 99%

“…Sequence analysis of chvE showed that it codes for a protein of at least 31.5 kDa that is homologous to the periplasmic ribose-binding protein and galactose/glucosebinding protein (GBP) of Escherichia coli (12). Upon binding their respective sugars, these proteins in E. coli interact with separate sites in the periplasmic domain of the methylaccepting transmembrane signal protein Trg, resulting in chemotaxis toward the sugars.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Sugars induce the Agrobacterium virulence genes through a periplasmic binding protein and a transmembrane signal protein.

Cangelosi

Ankenbauer

Nester

1990

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

Self Cite

302

269

View full text Add to dashboard Cite

Phenolic plant metabolites such as acetosyringone induce transcription of the virulence (vir) genes of Agrobactrium tumefaciens through the transmembrane VirA protein. We report here that certain sugars induce the vir genes synergistically with phenolic inducers by way of a distinct regulatory pathway that includes VirA and a chromosomally encoded virulence protein, ChvE. Sequence comparison showed that ChvE is a periplasmic galactose-binding protein corresponding to the GBP1 protein isolated from Agrobacterium radiobacter. Like homologous sugar-binding proteins in Escherichia coli, ChvE was required for chemotaxis toward galactose and several other -sugars. These sugars strongly induced vir gene expression in wild-type cells when acetosyringone was absent or present in low concentrations. Mutations in chvE abolished vir gene induction by sugars and resulted in a limited host range for infection but did not affect vir gene induction by acetosyringone. A mutant lacking the periplasmic domain of VirA exhibited the same regulatory phenotype and limited host range as chvE mutants. These data show that the vir genes are regulated by two separate classes of plant-derived inducers by way of distinct regulatory pathways that can be separated by mutation. Induction by sugars is essential for infection of some but not all plant hosts.Ti plasmids in Agrobacterium tumefaciens strains carry >20 virulence (vir) genes that code for most of the proteins involved in crown gall infection of wound sites on dicotyledonous plants. The biology of crown gall tumorigenesis, which involves transfer and integration of a piece of bacterial DNA into the host plant genome, has been reviewed recently (1,2). The vir genes are induced by phenolic plant metabolites such as acetosyringone. Two Ti plasmid gene products, the

show abstract

Synthesis of high specific radioactivity 3,5-[3H6]dimethoxy-4-hydroxyacetophenone, an inducing compound of the vir gene in Agrobacterium tumefaciens

Lee

Morimoto

Williams

1997

J Label Compd Radiopharm

View full text Add to dashboard Cite

Acetosyringone (3,5‐dimethoxy‐4‐hydroxyacetophenone, 1) is one of the plant signals that induce the vir genes of Agrobacterium tumefaciens which causes crown gall tumours on dicotyledonous plants. Vir gene induction is enhanced by other environmental factors like specific monosaccarides and acidic pH. However, it is still unclear how the inducer interacts with Agrobacterium. To identify the receptor(s) in Agrobacterium tumefaciens to which the plant signal binds, highly radioactive acetosyringone (3,5‐[3H6]dimethoxy‐4‐hydroxyacetophenone 6) was synthesized using C3H3I which was generated by two different methods. In Method 1, C3H3I was generated from 4‐[methyl‐3H]methoxy biphenyl to give methyl species with tritium NMR peak intensity ratios (C3H3: C3H2: C3HH2 = 44 : 42 : 14), and a calculated specific radioactivity of 56.1 Ci/mmole. Method 2 gave higher specific radioactivity reagent (72.6 Ci/mmole), with measured NMR peak intensity ratios of (3H3: C3H2: C3HH2 = 87 : 7 : 6). © John Wiley & Sons, Ltd.

show abstract

A chromosomal Agrobacterium tumefaciens gene required for effective plant signal transduction

Cited by 114 publications

References 51 publications

Genetic analysis of nonpathogenic Agrobacterium tumefaciens mutants arising in crown gall tumors

Genetic analysis of nonpathogenic Agrobacterium tumefaciens mutants arising in crown gall tumors

Sugars induce the Agrobacterium virulence genes through a periplasmic binding protein and a transmembrane signal protein.

Synthesis of high specific radioactivity 3,5-[3H6]dimethoxy-4-hydroxyacetophenone, an inducing compound of the vir gene in Agrobacterium tumefaciens

Contact Info

Product

Resources

About