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:Xylella fastidiosa is a phytopathogenic bacterium responsible for diseases in many economically important crops. Although different strains have been studied, little is known about X. fastidiosa stress responses. One of the best characterized stresses in bacteria is the heat shock response, which induces the expression of specific genes to prevent protein misfolding and aggregation, and to promote degradation of the irreversibly denatured polypeptides. To investigate X. fastidiosa genes involved in the heat shock response, we performed a whole genome microarray analysis in a time-course experiment. Globally, 261 genes were induced (9.7%) and 222 genes were repressed (8.3%). The expression profiles of the differentially expressed genes were grouped and their expression patterns were validated by quantitative RT-PCR experiments. As expected, genes that presented the higher induction rates encoded chaperones and proteases. We determined the transcription start site of six heat shock inducible genes and analyzed their promoter regions, which allowed us to propose a putative consensus for 32 promoters in Xylella and suggest additional genes as putative members of this regulon. Besides the induction of classical heat shock protein genes, we observed the up-regulation of virulence-associated genes such as vapD, hemagglutinins, hemolysin and xylan degrading enzymes, which may indicate the importance of heat stress to bacterial pathogenesis. In addition, we observed the repression of genes related to fimbriae, aerobic respiration, protein biosynthesis, and the induction of genes related to the extracytoplasmic stress response and some phage-related genes, revealing the complex network of genes that work together in response to heat shock. Keywords: stress response; heat shock response
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:To investigate the role(s) of a cold shock protein homolog (Csp1) in plant pathogenic bacteria Xylella fastidiosa, we compared transcriptome profiles between wild type and a csp1 deletion mutant (Δcsp1) using long read Nanopore RNA sequencing.
Project description:The global transcriptional response of the phytopathogenic bacterium X. fastidiosa to a sudden increase in salinity and osmolarity of the medium was investigated using DNA microarrays. Time-course experiments were carried out by exposing bacterial cells to high salinity (250 mM NaCl) and high osmolarity (300 mM sucrose) conditions revealing 142 upregulated genes under both stresses, including pathogenicity related genes, genes encoding transcriptional regulators, as well as genes related to DNA metabolism and mobile genetic elements. In addition, 38 genes were downregulated under both conditions, most of them related to ribosomal and heat shock proteins. A total of 192 genes were upregulated exclusively in the presence of NaCl, including genes encoding transporters, genes involved in oxidative-stress response and genes related to cell structure. A smaller number of genes (44 genes) were induced only in the presence of sucrose, most of them encoding hypothetical and conserved hypothetical proteins. Interestingly, 57% of the genes differentially expressed under both stress conditions have no putative function assigned, emphasizing the importance of high-throughput experiments to start the characterization of these genes in X. fastidiosa. Keywords: stress response, osmotic and salt stress
Project description:In the xylem vessels of susceptible hosts, such as citrus trees or grapevines, Xylella fastidiosa forms biofilm like-colonies that can block water transport, which appears to correlate to disease symptoms. Besides helping host colonization, bacterial biofilms play an important role in resistance against antimicrobial agents, for instance antimicrobial peptides (AMP). Here we show that gomesin, a potent AMP from a Brazilian tarantula spider, modulates X. fastidiosa gene expression profile upon 60 min treatment with a sublethal concentration. Data from DNA microarray hybridizations revealed that among the up-regulated coding sequences (CDS), some are related to biofilm production. In addition, we show that the biofilm formed by gomesin-treated bacteria is thicker than that formed by non-treated cells or cells exposed to streptomycin. We have also observed that treatment of X. fastidiosa with sublethal concentration of gomesin before inoculation in tobacco plants correlates with reduction in CVC symptoms, an effect possibly due to trapping of bacterial cells to fewer xylem vessels given the enhancement in biofilm production. Together, our results suggest that X. fastidiosa can selectively sense a sublethal concentration of gomesin modulating its gene expression to produce a stronger biofilm that may protect itself against the toxic effects of this AMP.
Project description:The global transcriptional response of the phytopathogenic bacterium X. fastidiosa to a sudden increase in salinity and osmolarity of the medium was investigated using DNA microarrays. Time-course experiments were carried out by exposing bacterial cells to high salinity (250 mM NaCl) and high osmolarity (300 mM sucrose) conditions revealing 142 upregulated genes under both stresses, including pathogenicity related genes, genes encoding transcriptional regulators, as well as genes related to DNA metabolism and mobile genetic elements. In addition, 38 genes were downregulated under both conditions, most of them related to ribosomal and heat shock proteins. A total of 192 genes were upregulated exclusively in the presence of NaCl, including genes encoding transporters, genes involved in oxidative-stress response and genes related to cell structure. A smaller number of genes (44 genes) were induced only in the presence of sucrose, most of them encoding hypothetical and conserved hypothetical proteins. Interestingly, 57% of the genes differentially expressed under both stress conditions have no putative function assigned, emphasizing the importance of high-throughput experiments to start the characterization of these genes in X. fastidiosa. Keywords: stress response, osmotic and salt stress Direct comparison between osmotic or salt stress condition and control (29oC) condition. Some hybridizations are dye-swaped. There are at least 3 biological replicates (independent harvest) and 2 technical replicates of each array (L - left and R - right).