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1.
Mol Plant Microbe Interact ; 20(3): 313-20, 2007 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-17378434

RESUMO

Salicylic acid (SA) is an important signaling molecule in local and systemic plant resistance. Following infection by microbial pathogens and the initial oxidative burst in plants, SA accumulation functions in the amplification of defense gene expression. Production of pathogenesis-related proteins and toxic antimicrobial chemicals serves to protect the plant from infection. Successful microbial pathogens utilize a variety of mechanisms to rid themselves of toxic antimicrobial compounds. Important among these mechanisms are multidrug-resistance pumps that bring about the active efflux of toxic compounds from microbial cells. Here, we show that a combination SA and its precursors, t-cinnamic acid and benzoic acid, can activate expression of specific multidrug efflux pump-encoding genes in the plant pathogen Erwinia chrysanthemi and enhance survival of the bacterium in the presence of model as well as plant-derived antimicrobial chemicals. This ability of plant-pathogenic bacteria to co-opt plant defense-signaling molecules to activate multidrug efflux pumps may have evolved to ensure bacterial survival in susceptible host plants.


Assuntos
Proteínas de Bactérias/genética , Dickeya chrysanthemi/genética , Genes Bacterianos , Proteínas de Bactérias/metabolismo , Ácido Benzoico/farmacologia , Transporte Biológico/efeitos dos fármacos , Cichorium intybus/microbiologia , Cinamatos/farmacologia , Dickeya chrysanthemi/crescimento & desenvolvimento , Dickeya chrysanthemi/metabolismo , Resistência Microbiana a Medicamentos/genética , Resistência a Múltiplos Medicamentos/genética , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Immunoblotting , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Análise de Sequência com Séries de Oligonucleotídeos , Folhas de Planta/microbiologia , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Ácido Salicílico/farmacologia
2.
J Bacteriol ; 185(19): 5772-8, 2003 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-13129948

RESUMO

TolC is the outer-membrane component of several multidrug resistance (MDR) efflux pumps and plays an important role in the survival and virulence of many gram-negative bacterial animal pathogens. We have identified and characterized the outer-membrane protein-encoding gene tolC in the bacterial plant pathogen Erwinia chrysanthemi EC16. The gene was found to encode a 51-kDa protein with 70% identity to its Escherichia coli homologue. The E. chrysanthemi gene was able to functionally complement the E. coli tolC gene with respect to its role in MDR efflux pumps. A tolC mutant of E. chrysanthemi was found to be extremely sensitive to antimicrobial agents, including several plant-derived chemicals. This mutant was unable to grow in planta and its ability to cause plant tissue maceration was severely compromised. The tolC mutant was shown to be defective in the efflux of berberine, a model antimicrobial plant chemical. These results suggest that by conferring resistance to the antimicrobial compounds produced by plants, the E. chrysanthemi tolC plays an important role in the survival and colonization of the pathogen in plant tissue.


Assuntos
Proteínas da Membrana Bacteriana Externa/metabolismo , Berberina/farmacologia , Dickeya chrysanthemi/patogenicidade , Farmacorresistência Bacteriana , Plantas/química , Antibacterianos/farmacologia , Proteínas da Membrana Bacteriana Externa/genética , Cichorium intybus/microbiologia , Dickeya chrysanthemi/efeitos dos fármacos , Dickeya chrysanthemi/genética , Dickeya chrysanthemi/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Proteínas de Escherichia coli , Proteínas de Membrana Transportadoras , Testes de Sensibilidade Microbiana , Mutação , Doenças das Plantas/microbiologia , Folhas de Planta/microbiologia , Virulência
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