The exbD2 gene as well as the iron-uptake genes tonB, exbB and exbD1 of Xanthomonas campestris pv. campestris are essential for the induction of a hypersensitive response on pepper (Capsicum annuum)

Wiggerich, Heinrich-G.; Pühler, Alfred

doi:10.1099/00221287-146-5-1053

Cited by 39 publications

(32 citation statements)

References 37 publications

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“…To our knowledge, only two reports have previously described two ExbD proteins encoded within the same TonB cluster in other Gram-negative microorganisms (43,44). In both cases, it was found that only one of the two ExbD proteins was involved in iron uptake functions, an observation that contrasts with our results showing that both exbD products are required for iron acquisition.…”

Section: Discussioncontrasting

confidence: 57%

Functional Features of TonB Energy Transduction Systems of Acinetobacter baumannii

et al. 2013

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Acinetobacter baumannii is an opportunistic pathogen that causes severe nosocomial infections. Strain ATCC 19606 T utilizes the siderophore acinetobactin to acquire iron under iron-limiting conditions encountered in the host. Accordingly, the genome of this strain has three tonB genes encoding proteins for energy transduction functions needed for the active transport of nutrients, including iron, through the outer membrane. Phylogenetic analysis indicates that these tonB genes, which are present in the genomes of all sequenced A. baumannii strains, were acquired from different sources. Two of these genes occur as components of tonB-exbB-exbD operons and one as a monocistronic copy; all are actively transcribed in ATCC 19606T . The abilities of components of these TonB systems to complement the growth defect of Escherichia coli W3110 mutants KP1344 (tonB) and RA1051 (exbBD) under iron-chelated conditions further support the roles of these TonB systems in iron acquisition. Mutagenesis analysis of ATCC 19606 T tonB 1 (subscripted numbers represent different copies of genes or proteins) and tonB 2 supports this hypothesis: their inactivation results in growth defects in iron-chelated media, without affecting acinetobactin biosynthesis or the production of the acinetobactin outer membrane receptor protein BauA. In vivo assays using Galleria mellonella show that each TonB protein is involved in, but not essential for, bacterial virulence in this infection model. Furthermore, we observed that TonB 2 plays a role in the ability of bacteria to bind to fibronectin and to adhere to A549 cells by uncharacterized mechanisms. Taken together, these results indicate that A. baumannii ATCC 19606 T produces three independent TonB proteins, which appear to provide the energy-transducing functions needed for iron acquisition and cellular processes that play a role in the virulence of this pathogen.

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Section: Discussioncontrasting

confidence: 57%

Functional Features of TonB Energy Transduction Systems of Acinetobacter baumannii

et al. 2013

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“…In Xanthomonas campestris pv. campestris, which causes black rot of cruciferous plants, a tonB mutant is impaired for ferric ion uptake and exhibits increased extracellular siderophore production and reduced disease symptoms (72,73). In Xanthomonas oryzae pv.…”

mentioning

confidence: 99%

Role of the FeoB Protein and Siderophore in Promoting Virulence ofXanthomonas oryzaepv. oryzae on Rice

Pandey

Sonti

2010

J Bacteriol

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Xanthomonas oryzae pv. oryzae causes bacterial blight, a serious disease of rice. Our analysis revealed that the X. oryzae pv. oryzae genome encodes genes responsible for iron uptake through FeoB (homolog of the major bacterial ferrous iron transporter) and a siderophore. A mutation in the X. oryzae pv. oryzae feoB gene causes severe virulence deficiency, growth deficiency in iron-limiting medium, and constitutive production of a siderophore. We identified an iron regulated xss gene cluster, in which xssABCDE (Xanthomonas siderophore synthesis) and xsuA (Xanthomonas siderophore utilization) genes encode proteins involved in biosynthesis and utilization of X. oryzae pv. oryzae siderophore. Mutations in the xssA, xssB, and xssE genes cause siderophore deficiency and growth restriction under iron-limiting conditions but are virulence proficient. An xsuA mutant displayed impairment in utilization of native siderophore, suggesting that XsuA acts as a specific receptor for a ferric-siderophore complex. Histochemical and fluorimetric assays with gusA fusions indicate that, during in planta growth, the feoB gene is expressed and that the xss operon is not expressed. This study represents the first report describing a role for feoB in virulence of any plant-pathogenic bacterium and the first functional characterization of a siderophore-biosynthetic gene cluster in any xanthomonad.

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“…The TonB system also mediates the signal transduction from the cellular surface to the cytoplasm, as reported in E. coli and Pseudomonas putida (Harle et al, 1995;Koster et al, 1994). In X. campestris, the genes involved in the uptake of Fe are essential for the induction of a hypersensitive response (Wiggerich and Puhler, 2000).…”

Section: Mehta and Rosato 145mentioning

confidence: 99%

Identification of differentially expressed genes of Xanthomonas axonopodis pv. citri by representational difference analysis of cDNA

Mehta

Rosato

2005

Genet. Mol. Biol.

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Xanthomonas axonopodis pv. citri is a phytopathogenic bacterium responsible for citrus canker, a serious disease which causes severe losses in citriculture around the world. In this study we report the differential expression of X. axonopodis pv. citri in response to specific treatments by using Representational Difference Analysis of cDNA (cDNA RDA). cDNAs from X. axonopodis pv. citri cultured in the presence of leaf extract of the host plant (Citrus sinensis), in vivo, as well as in the complex medium were hybridized against cDNA of the bacterium grown in the minimal medium. Sequencing of the difference products obtained after the second and third hybridizations revealed a total of 37 distinct genes identified by homology searches in the genome of X. axonopodis pv. citri. These genes were distributed in different functional categories, including genes that encode hypothetical proteins, genes involved in metabolism, cellular processes and pathogenicity, and mobile genetic elements. Most of these genes are likely related to growth and/or acquisition of nutrients in specific treatments whereas others might be important for the bacterium pathogenicity.

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The exbD2 gene as well as the iron-uptake genes tonB, exbB and exbD1 of Xanthomonas campestris pv. campestris are essential for the induction of a hypersensitive response on pepper (Capsicum annuum)

Cited by 39 publications

References 37 publications

Functional Features of TonB Energy Transduction Systems of Acinetobacter baumannii

Functional Features of TonB Energy Transduction Systems of Acinetobacter baumannii

Role of the FeoB Protein and Siderophore in Promoting Virulence ofXanthomonas oryzaepv. oryzae on Rice

Identification of differentially expressed genes of Xanthomonas axonopodis pv. citri by representational difference analysis of cDNA

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