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  • 1
    Online Resource
    Online Resource
    Mutational Analysis of Xanthomonas Harpin HpaG Identifies a Key Functional Region That Elicits the Hypersensitive Response in Nonhost Plants
    American Society for Microbiology ; 2004
    In:  Journal of Bacteriology Vol. 186, No. 18 ( 2004-09-15), p. 6239-6247
    Details
    In: Journal of Bacteriology, American Society for Microbiology, Vol. 186, No. 18 ( 2004-09-15), p. 6239-6247
    Abstract: HpaG is a type III-secreted elicitor protein of Xanthomonas axonopodis pv. glycines. We have determined the critical amino acid residues important for hypersensitive response (HR) elicitation by random and site-directed mutagenesis of HpaG and its homolog XopA. A plasmid clone carrying hpaG was mutagenized by site-directed mutagenesis, hydroxylamine mutagenesis, and error-prone PCR. A total of 52 mutants were obtained, including 51 single missense mutants and 1 double missense mutant. The HR elicitation activity was abolished in the two missense mutants [HpaG(L50P) and HpaG(L43P/L50P)]. Seven single missense mutants showed reduced activity, and the HR elicitation activity of the rest of the mutants was similar to that of wild-type HpaG. Mutational and deletion analyses narrowed the region essential for elicitor activity to the 23-amino-acid peptide (H 2 N-NQGISEKQLDQLLTQLIMALLQQ-COOH). A synthetic peptide of this sequence possessed HR elicitor activity at the same concentration as the HpaG protein. This region has 78 and 74% homology with 23- and 27-amino-acid regions of the HrpW harpin domains, respectively, from Pseudomonas and Erwinia spp. The secondary structure of the peptide is predicted to be an α-helix, as is the HrpW region that is homologous to HpaG. The predicted α-helix of HpaG is probably critical for the elicitation of the HR in tobacco plants. In addition, mutagenesis of a xopA gene yielded two gain-of-function mutants: XopA(F48L) and XopA(F48L/M52L). These results indicate that the 12 amino acid residues between L39 and L50 of HpaG have critical roles in HR elicitation in tobacco plants.
    Type of Medium: Online Resource
    ISSN: 0021-9193 , 1098-5530
    URL: Article
    DOI: 10.1128/JB.186.18.6239-6247.2004
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2004
    detail.hit.zdb_id: 1481988-0
    SSG: 12
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  • 2
    Online Resource
    Online Resource
    Biochemical Evidence for ToxR and ToxJ Binding to the tox Operons of Burkholderia glumae and Mutational Analysis of ToxR
    American Society for Microbiology ; 2009
    In:  Journal of Bacteriology Vol. 191, No. 15 ( 2009-08), p. 4870-4878
    Details
    In: Journal of Bacteriology, American Society for Microbiology, Vol. 191, No. 15 ( 2009-08), p. 4870-4878
    Abstract: Burkholderia glumae produces toxoflavin, a phytotoxin with a broad host range, which is a key virulence factor in bacterial rice grain rot. Based on genetic analysis, we previously reported that ToxR, a LysR-type regulator, activates both the toxABCDE (toxoflavin biosynthesis genes) and toxFGHI (toxoflavin transporter genes) operons in the presence of toxoflavin as a coinducer. Quorum sensing regulates the expression of the transcriptional activator ToxJ that is required for tox gene expression. Here, we used gel mobility shift and DNase I protection analyses to demonstrate that both ToxR and ToxJ bind simultaneously to the regulatory regions of both tox operons. ToxR and ToxJ both bound to the toxA and toxF regulatory regions, and the sequences for the binding of ToxR to the regulatory regions of both tox operons possessed T-N 11 -A motifs. Following random mutagenesis of toxR , 10 ToxR mutants were isolated. We constructed a reporter strain, S6K34 ( toxR ′ A ′::Ω toxF ::Tn 3 - gusA34 ) to evaluate which amino acid residues are important for ToxR activity. Several single amino acid substitutions identified residues that might be important for ToxR binding to DNA and toxoflavin binding. When various toxoflavin derivatives were tested to determine whether toxoflavin is a specific coinducer of ToxR in the S6K34 strain, ToxR, together with toxoflavin, conferred toxF expression, whereas 4,8-dihydrotoxoflavin did so only slightly. With these results, we have demonstrated biochemically that B. glumae cells control toxoflavin production tightly by the requirement of both ToxJ and toxoflavin as coinducers of ToxR.
    Type of Medium: Online Resource
    ISSN: 0021-9193 , 1098-5530
    URL: Article
    DOI: 10.1128/JB.01561-08
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2009
    detail.hit.zdb_id: 1481988-0
    SSG: 12
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  • 3
    Online Resource
    Online Resource
    Amyloidogenesis of Type III-dependent Harpins from Plant Pathogenic Bacteria
    Elsevier BV ; 2007
    In:  Journal of Biological Chemistry Vol. 282, No. 18 ( 2007-05), p. 13601-13609
    Details
    In: Journal of Biological Chemistry, Elsevier BV, Vol. 282, No. 18 ( 2007-05), p. 13601-13609
    Type of Medium: Online Resource
    ISSN: 0021-9258
    URL: Article
    DOI: 10.1074/jbc.M602576200
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2007
    detail.hit.zdb_id: 2141744-1
    detail.hit.zdb_id: 1474604-9
    SSG: 12
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  • 4
    Online Resource
    Online Resource
    Characterization of the Xanthomonas axonopodis pv. glycines Hrp Pathogenicity Island
    American Society for Microbiology ; 2003
    In:  Journal of Bacteriology Vol. 185, No. 10 ( 2003-05-15), p. 3155-3166
    Details
    In: Journal of Bacteriology, American Society for Microbiology, Vol. 185, No. 10 ( 2003-05-15), p. 3155-3166
    Abstract: We sequenced an approximately 29-kb region from Xanthomonas axonopodis pv. glycines that contained the Hrp type III secretion system, and we characterized the genes in this region by Tn 3-gus mutagenesis and gene expression analyses. From the region, hrp (hypersensitive response and pathogenicity) and hrc ( hrp and conserved) genes, which encode type III secretion systems, and hpa ( hrp -associated) genes were identified. The characteristics of the region, such as the presence of many virulence genes, low G+C content, and bordering tRNA genes, satisfied the criteria for a pathogenicity island (PAI) in a bacterium. The PAI was composed of nine hrp , nine hrc , and eight hpa genes with seven plant-inducible promoter boxes. The hrp and hrc mutants failed to elicit hypersensitive responses in pepper plants but induced hypersensitive responses in all tomato plants tested. The Hrp PAI of X. axonopodis pv. glycines resembled the Hrp PAIs of other Xanthomonas species, and the Hrp PAI core region was highly conserved. However, in contrast to the PAI of Pseudomonas syringae , the regions upstream and downstream from the Hrp PAI core region showed variability in the xanthomonads. In addition, we demonstrate that HpaG, which is located in the Hrp PAI region of X. axonopodis pv. glycines, is a response elicitor. Purified HpaG elicited hypersensitive responses at a concentration of 1.0 μM in pepper, tobacco, and Arabidopsis thaliana ecotype Cvi-0 by acting as a type III secreted effector protein. However, HpaG failed to elicit hypersensitive responses in tomato, Chinese cabbage, and A. thaliana ecotypes Col-0 and Ler. This is the first report to show that the harpin-like effector protein of Xanthomonas species exhibits elicitor activity.
    Type of Medium: Online Resource
    ISSN: 0021-9193 , 1098-5530
    URL: Article
    DOI: 10.1128/JB.185.10.3155-3166.2003
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2003
    detail.hit.zdb_id: 1481988-0
    SSG: 12
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  • 5
    Online Resource
    Online Resource
    Comparative analysis of three indigenous plasmids from Xanthomonas axonopodis pv. glycines
    Elsevier BV ; 2006
    In:  Plasmid Vol. 56, No. 2 ( 2006-9), p. 79-87
    Details
    In: Plasmid, Elsevier BV, Vol. 56, No. 2 ( 2006-9), p. 79-87
    Type of Medium: Online Resource
    ISSN: 0147-619X
    URL: Article
    DOI: 10.1016/j.plasmid.2006.03.001
    RVK:
    WA 15000
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2006
    detail.hit.zdb_id: 1471554-5
    SSG: 12
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