Project description:Genome sequence analysis of the bacterium Xylella fastidiosa revealed the presence of two genes, named rpoE and rseA, predicted to encode an ECF sigma factor and an anti-sigma factor, respectively. In this work, an rpoE null mutant was constructed in the citrus strain J1a12 and shown to be sensitive to exposure to heat shock and ethanol. To identify the X. fastidiosa σE regulon, global gene expression profiles were obtained by DNA microarray analysis of bacterial cells under heat shock identifying 23 sigmaE-dependent genes. Keywords: stress response, heat shock, rpoE mutant strain
Project description:This is the study of the Heat Shock response of phytopathogenic bacteria Xylella fastidiosa. This series keeps the 25 minutes 40oC stimulus response (Aug 2005). Keywords: stress response; heat shock response
Project description:Investigation of whole genome gene expression level changes in Xylella fastidiosa grown in minimal media XFM and XFM supplied with pectin or glucan (Host polysaccharides) , compared to cell grown in the complex media PWG. The cells grown in the minimal medium XFM supplied with host polysaccharides specially pectin are transmissible by the insect vector when delivered to the vector through artificial diet system. This does not happen with cells grown in the complex media. 4 (4 plex chips) study using total RNA recovered from 4 independents replicates for Xylella fastidiosa grown on PWG, XFM, XFM-glucan and XFM-pectin.
Project description:Xylella fastidiosa is the etiologic agent of a wide range of plant diseases including citrus variegated chlorosis (CVC), a major threat to the Brazilian citrus industry. Genome sequences of several strains of this phytopathogen are accessible, enabling large-scale functional studies. Transcript levels in different iron availabilities were assessed with DNA microarrays representing 2608 (91.6%) coding sequences (CDS) of X. fastidiosa CVC strain 9a5c. When treated with the iron chelator 2,2-dipyridyl, 193 CDS were considered as up-regulated and 216 as down-regulated. In the presence of 100uM of ferric pyrophosphate, 218 and 256 CDS were considered as up- and down-regulated, respectively. Differential expression for a subset of 44 CDS was further evaluated by reverse transcription - quantitative PCR that showed a Pearson correlation of 0.77 with array results. The CDS differentially expressed upon the iron concentration shift participate in diverse cellular functions. Many CDS involved with regulatory functions, pathogenicity and cell structure, were modulated in both conditions tested suggesting that major changes in cell architecture and metabolism occur when X. fastidiosa cells are exposed to extreme variations in iron concentration. Interestingly, the modulated CDS include those related to colicin V-like bacteriocin synthesis and secretion and to pili/fimbriae functions. We also investigated the contribution of the ferric uptake regulator Fur to the iron regulon of X. fastidiosa. The promoter regions of strain 9a5c genome were screened for putative Fur boxes and candidates were analyzed by electrophoretic mobility shift assays. Taken together, our data support the hypothesis that Fur is not solely responsible for the modulation of the iron regulon of X. fastidiosa and present novel evidence for iron regulation of pathogenicity determinants. Keywords: stress response; response to iron-replete condition
