Mapping of Agrobacterium tumefaciens chromosomal genes affecting cellulose synthesis and bacterial attachment to host cells

Robertson, Jennifer L.; Holliday, Trenton W.; Matthysse, Ann G.

doi:10.1128/jb.170.3.1408-1411.1988

Cited by 36 publications

(24 citation statements)

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“…Our laboratory has previously identified and mapped three closely-linked chromosomal Tn5 mutants of A. tumefaciens which were avirulent and unable to bind to plant cells (16,22). Random clones from a library of A. tumefaciens DNA were transferred to one of these mutants, Att-C43.…”

Section: Resultsmentioning

confidence: 99%

“…We have previously isolated three Tn5 nonattaching mutants (16). These mutants all mapped to the same region of the bacterial chromosome (close to met6) and contained Tn5 insertions in a large EcoRI fragment (22). In order to characterize the process of bacterial attachment and to identify the genes involved, we examined this region of chromosomal DNA in greater detail.…”

Section: Infections Of Wound Sites In Dicotyledonous Plants Bymentioning

confidence: 99%

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Requirement for genes with homology to ABC transport systems for attachment and virulence of Agrobacterium tumefaciens

1996

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Transposon mutants of Agrobacterium tumefaciens which were avirulent and unable to attach to plant cells were isolated and described previously. A clone from a library of Agrobacterium tumefaciens DNA which was able to complement these chromosomal att mutants was identified. Tn3HoHo1 insertions in this clone were made and used to replace the wild-type genes in the bacterial chromosome by marker exchange. The resulting mutants were avirulent and showed either no or very much reduced attachment to carrot suspension culture cells. We sequenced a 10-kb region of this clone and found a putative operon containing nine open reading frames (ORFs) (attA1A2BCDEFGH). The second and third ORFs (attA2 and attB) showed homology to genes encoding the membrane-spanning proteins (potB and potH; potC and potI) of periplasmic binding proteindependent (ABC) transport systems from gram-negative bacteria. The homology was strongest to proteins involved in the transport of spermidine and putrescine. The first and fifth ORFs (attA1 and attE) showed homology to the genes encoding ATP-binding proteins of these systems including potA, potG, and cysT from Escherichia coli; occP from A. tumefaciens; cysA from Synechococcus spp.; and ORF-C from an operon involved in the attachment of Campylobacter jejuni. The ability of mutants in these att genes to bind to host cells was restored by addition of conditioned medium during incubation of the bacteria with host cells. Infections of wound sites in dicotyledonous plants byAgrobacterium tumefaciens result in the formation of crown gall tumors. The mechanism of pathogenesis involves the transfer of a DNA fragment (T-DNA) from the bacterial Ti plasmid to the plant host cell (4). An early step in tumor formation is attachment of bacteria to the plant cell surface (15). This attachment is required for pathogenesis since all known nonattaching mutants are avirulent (3,5,16,25). We have previously isolated three Tn5 nonattaching mutants (16). These mutants all mapped to the same region of the bacterial chromosome (close to met6) and contained Tn5 insertions in a large EcoRI fragment (22). In order to characterize the process of bacterial attachment and to identify the genes involved, we examined this region of chromosomal DNA in greater detail. MATERIALS AND METHODSBacterial strains, plasmids, and growth conditions. Bacterial strains and plasmids used in this study were as previously described (14,16,19). Bacteria were grown in Luria broth, nutrient broth, or minimal medium, and viable cell counts were determined as previously described (14). A. tumefaciens was grown at 25ЊC. Escherichia coli was grown at 37ЊC. Antibiotics were used at the following concentrations: carbenicillin, 50 mg/liter; tetracycline, 10 mg/liter; chloramphenicol, 100 mg/liter; neomycin, 20 mg/liter for liquid media and 60 mg/liter for agar media; and gentamycin, 50 mg/liter. A library of A. tumefaciens NT1 DNA cloned as Sau3a partial digestion products into the BamHI site of pCP13 was obtained from S. Farrand. A library of A. tumef...

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Section: Resultsmentioning

confidence: 99%

Section: Infections Of Wound Sites In Dicotyledonous Plants Bymentioning

confidence: 99%

Requirement for genes with homology to ABC transport systems for attachment and virulence of Agrobacterium tumefaciens

1996

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“…The second binding step requires the synthesis of bacterial cellulose, which causes a tight, irreversible binding and formation of bacterial aggregates on the host surface (314,413). Mutants with mutations of the A. tumefaciens celABCDE operon no longer synthesize cellulose and can be readily dissociated from cultured plant cells by vortexing.…”

Section: Binding To Host Surfacesmentioning

confidence: 99%

Detection of and Response to Signals Involved in Host-Microbe Interactions by Plant-Associated Bacteria

Brencic

Winans

2005

Microbiol Mol Biol Rev

339

208

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Diverse interactions between hosts and microbes are initiated by the detection of host-released chemical signals. Detection of these signals leads to altered patterns of gene expression that culminate in specific and adaptive changes in bacterial physiology that are required for these associations. This concept was first demonstrated for the members of the family Rhizobiaceae and was later found to apply to many other plant-associated bacteria as well as to microbes that colonize human and animal hosts. The family Rhizobiaceae includes various genera of rhizobia as well as species of Agrobacterium. Rhizobia are symbionts of legumes, which fix nitrogen within root nodules, while Agrobacterium tumefaciens is a pathogen that causes crown gall tumors on a wide variety of plants. The plant-released signals that are recognized by these bacteria are low-molecular-weight, diffusible molecules and are detected by the bacteria through specific receptor proteins. Similar phenomena are observed with other plant pathogens, including Pseudomonas syringae, Ralstonia solanacearum, and Erwinia spp., although here the signals and signal receptors are not as well defined. In some cases, nutritional conditions such as iron limitation or the lack of nitrogen sources seem to provide a significant cue. While much has been learned about the process of host detection over the past 20 years, our knowledge is far from being complete. The complex nature of the plant-microbe interactions makes it extremely challenging to gain a comprehensive picture of host detection in natural environments, and thus many signals and signal recognition systems remain to be described

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“…Mapping of the location on the chromosome of the TnS insertions in each of the three mutants was done by the R' mapping procedure of Robertson et al (22).…”

Section: Methodsmentioning

confidence: 99%

Characterization of three Agrobacterium tumefaciens avirulent mutants with chromosomal mutations that affect induction of vir genes

et al. 1991

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Three Agrobacterium tumefaciens mutants with chromosomal mutations that affect bacterial virulence were isolated by transposon mutagenesis. Two of the mutants were avirulent on all hosts tested. The third mutant, Ivr-211, was a host range mutant which was avirulent on BryophyUum diagremontiana, Nicotiana tabacum, N. Infection of susceptible dicotyledonous plants by Agrobacterium tumefaciens results in crown gall tumor formation. The mechanism by which the bacterium infects the plant is not fully understood. An early step in tumor formation involves the attachment of the bacterium to host plant cells (12). Once attached to the plant, the bacterium begins a process that results in the movement of tumor-inducing (Ti) plasmid DNA sequences from the bacterium into the plant host genome (2, 28). Depicker et al. have identified the DNA sequences transferred and termed them T-DNA (5). Without successful transfer of the T-DNA from the bacterium to the plant, tumor formation cannot occur. This paper examines the properties of three avirulent TnS insertion mutants of A. tumefaciens,. These TnS insertions are contained within the chromosome of the bacterium; thus, the insertions have no direct affect on the vir region of the Ti plasmid which is responsible for T-DNA transfer. The only previously identified chromosomal genes required for virulence are chvA and chvB (6), att (16), pscA (27) (also called exoC [1]), chvD (32), and chvE (9). Mutations in each of the first four genes listed result in the inability of the bacteria to attach to host cells and the consequent loss of bacterial virulence. Mutations in chvD result in reduced virulence on Bryophyllum diagremontiana (visible tumors were still formed) and reduced induction of virG by acetosyringone (32). Transposon insertions in chvE result in a * Corresponding author.

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Mapping of Agrobacterium tumefaciens chromosomal genes affecting cellulose synthesis and bacterial attachment to host cells

Cited by 36 publications

References 14 publications

Requirement for genes with homology to ABC transport systems for attachment and virulence of Agrobacterium tumefaciens

Requirement for genes with homology to ABC transport systems for attachment and virulence of Agrobacterium tumefaciens

Detection of and Response to Signals Involved in Host-Microbe Interactions by Plant-Associated Bacteria

Characterization of three Agrobacterium tumefaciens avirulent mutants with chromosomal mutations that affect induction of vir genes

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