Identificação de genes com expressão modulada por estreptomicina e de genes associados à virulência e patogenicidade em Xylella fastidiosa [thesis]

Patrícia Isabela Pessoa da Silva
Agradecimentos Agradeço primeiramente a Deus, pela força e por guiar meus caminhos. Aos meus pais, Dalva e Valdo, por todos os ensinamentos, valores e dedicação. Às minhas irmãs, Renata e Fernanda, por serem presentes em minha vida e por serem pessoas com quem verdadeiramente sempre poderei contar. Ao Henrique, por existir e tornar nossas vidas mais felizes. Ao Chico, por ter facilitado em todos os sentidos essa minha longa jornada. Aos tios (Darcy, Ademar, Déa, Aparecida, Piedade, Cleiner e
more » ... edade, Cleiner e Rose) e primos (Kátia, Daniela, Anna Clara e Bruno), pelos bons momentos que me proporcionaram cada vez que retornei à minha cidade, fazendo com que eu me sentisse importante e amada. A Cida Palavras chave: Fitopatógeno, Clorose Variegada dos Citros, Estreptomicina, Perfil de expressão gênica, Pirosequenciamento, Genômica comparativa. Abstract Abstract DA SILVA, P.I.P. Identification of genes modulated by streptomycin and of genes related to virulence and pathogenicity in Xylella fastidiosa. 2010. 138 f. PhD Thesis -Instituto de Química, Universidade de São Paulo, São Paulo. At sublethal concentrations, antimicrobials compounds modulate bacterial gene expression and the gene set that is modulated depends not only on the bacterial strain but also on the nature of antimicrobial agent. In this study, we evaluated changes in gene expression profile of Xylella fastidiosa strain 9a5c exposed up to 60 min to sublethal concentration of streptomycin. This a virulent strain originally isolated from orange trees with symptoms of citrus variegated chlorosis. Hybridization of DNA microarrays representing 2,608 out of 2848 coding sequences (CDS) previously annotated in strain 9a5c genome revealed 136 CDS differentially expressed upon streptomycin treatment. Of which 109 were down-regulated and 27 up-regulated. Differential expression for a subset of 21 CDS was further evaluated by reverse transcription-quantitative PCR (RT-qPCR). In addition, we performed an integrated analysis of the gene expression profile of X. fastidiosa in response to streptomycin along with other gene expression profiles available for this bacterium. Among the up-regulated CDS, we highlight those encoding chaperonins GroEL and GroES, which are associated with heat shock response, and those CDS related to translation, such as ribosomal proteins and translation factors. Interestingly, exposure to streptomycin induces the expression of a CDS encoding polygalacturonase, which is a virulence factor for some X. fastidiosa strains. Furthermore, treatment with streptomycin down-regulates some CDS related to biofilm formation oppositely to treatment with gomesin, an antimicrobial peptide. Together, these observations suggest that exposure to sublethal dose of streptomycin might promote a higher virulent phenotype, in contrast to the effect previously observed with gomesin. In the present work, we also describe the pyrosequencing of J1a12 genome, a X. fastidiosa strain that exhibits a less virulent phenotype in citrus and tobacco if compared to strain 9a5c. A comparison of genome sequences of these two strains confirms differences previously observed using DNA microarrays and highlights important genes for virulence of X. fastidiosa.
doi:10.11606/t.46.2010.tde-01032011-140806 fatcat:rzulqlgy2ndr3ifdqjznhrlsqe