Structural and functional characterization of the lexA gene of Xanthomonas campestris pathovar citri.

Yang, Y C; Yang, M K; Kuo, T T; Tu, J

Yang, Y C; Yang, M K; Kuo, T T; Tu, J.

Afiliación

Yang YC; Institute of Life Science, National Defense Medical Center, Taipei, Taiwan, Republic of China.

Mol Genet Genomics ; 265(2): 316-26, 2001 Apr.

Article en En | MEDLINE | ID: mdl-11361343

RESUMEN

The role of the LexA protein and, specifically, its effect on recA expression were analyzed in Xanthomonas campestris pathovar citri (X.c. pv. citri). Overexpression of LexA from X.c. pv. citri, in the plant pathogen, as well as in Escherichia coli, results in increased sensitivity to the DNA-damaging agents mitomycin C and ultraviolet radiation, indicating that the recombinant X.c. pv. citri LexA protein is functional in a different bacterial species. Immunoblot analysis revealed that the overexpressed LexA protein functioned as a repressor of recA expression in X.c. pv. citri, and that the mitomycin C-induced increase in the abundance of RecA was accompanied by specific proteolysis of LexA that required RecA. Although the LexA protein from X.c. pv. citri also blocked the expression of recA in E. coli, the E. coli RecA protein was not able to support the autocatalytic cleavage of LexA from the plant pathogen. The transcription start site of the X.c. pv. citri lexA gene was identified, and the region upstream of this gene was shown to confer responsiveness to mitomycin C on a luciferase reporter gene construct. Electrophoretic mobility-shift assays demonstrated that X.c. pv. citri LexA interacts with the promoter region of X.c. pv. citri lexA, as well as with those of the recA genes of X.c. pv. citri and E. coli. These results indicate that LexA functions as a repressor of gene expression in X.c. pv. citri just as it does in E. coli.

Asunto(s)

Proteínas Bacterianas/fisiología; Proteínas de Unión al ADN; Regulación Bacteriana de la Expresión Génica; Rec A Recombinasas/genética; Proteínas Represoras/fisiología; Serina Endopeptidasas/fisiología; Xanthomonas campestris/genética; Proteínas Bacterianas/genética; Proteínas Bacterianas/metabolismo; Secuencia de Bases; Daño del ADN; ADN Bacteriano; Escherichia coli; Genes Bacterianos; Mitomicina/farmacología; Datos de Secuencia Molecular; Inhibidores de la Síntesis del Ácido Nucleico/farmacología; Regiones Promotoras Genéticas; Rec A Recombinasas/metabolismo; Proteínas Represoras/genética; Proteínas Represoras/metabolismo; Serina Endopeptidasas/genética; Serina Endopeptidasas/metabolismo; Xanthomonas campestris/efectos de los fármacos; Xanthomonas campestris/efectos de la radiación

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Colección: 01-internacional Base de datos: MEDLINE Asunto principal: Rec A Recombinasas / Proteínas Represoras / Proteínas Bacterianas / Serina Endopeptidasas / Regulación Bacteriana de la Expresión Génica / Xanthomonas campestris / Proteínas de Unión al ADN Tipo de estudio: Prognostic_studies Idioma: En Revista: Mol Genet Genomics Asunto de la revista: BIOLOGIA MOLECULAR / GENETICA Año: 2001 Tipo del documento: Article País de afiliación: China Pais de publicación: Alemania

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