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:Xylella fastidiosa regulates traits important to both virulence of grape as well as colonization of sharpshooter vectors via its production of a fatty acid signal molecule known as DSF whose production is dependent on rpfF. While X. fastidiosa rpfF mutants exhibit increased virulence to plants they are unable to be spread from plant to plant by insect vectors. To gain more insight into the traits that contribute to these processes, a DNA microarray for this species was designed and utilized to determine the RpfF-dependent regulon by transcriptional profiling. A total of 447 genes whose expression was significantly different between the wild type and an rpfF mutant (FDR<0.05) were identified when cells were grown in PW liquid medium. Among them, 165 genes were down-regulated in the rpfF mutant compared to the wild type strain whereas 282 genes were over-expressed. RpfF function was required for regulation of eleven regulatory and sigma factors including rpfE, yybA, PD1177, glnB, rpfG, PD0954, PD0199, PD2050, colR, rpoH, and rpoD. In general, RpfF is required for regulation of genes involved in attachment and biofilm formation, enhancing expression of hemagglutinin genes hxfA and hxfB and suppressing most type IV pili and gum genes. A large number of other RpfF-dependent genes that might contribute to virulence or insect colonization were also identified such as those encoding hemolysin, colicin V, as well as genes with unknown functions.
Project description:Xylella fastidiosa regulates traits important to both virulence of grape as well as colonization of sharpshooter vectors via its production of a fatty acid signal molecule known as DSF whose production is dependent on rpfF. While X. fastidiosa rpfF mutants exhibit increased virulence to plants they are unable to be spread from plant to plant by insect vectors. To gain more insight into the traits that contribute to these processes, a DNA microarray for this species was designed and utilized to determine the RpfF-dependent regulon by transcriptional profiling. A total of 447 genes whose expression was significantly different between the wild type and an rpfF mutant (FDR<0.05) were identified when cells were grown in PW liquid medium. Among them, 165 genes were down-regulated in the rpfF mutant compared to the wild type strain whereas 282 genes were over-expressed. RpfF function was required for regulation of eleven regulatory and sigma factors including rpfE, yybA, PD1177, glnB, rpfG, PD0954, PD0199, PD2050, colR, rpoH, and rpoD. In general, RpfF is required for regulation of genes involved in attachment and biofilm formation, enhancing expression of hemagglutinin genes hxfA and hxfB and suppressing most type IV pili and gum genes. A large number of other RpfF-dependent genes that might contribute to virulence or insect colonization were also identified such as those encoding hemolysin, colicin V, as well as genes with unknown functions. Two samples and one time-points experiment. Two biological and dye-swap replicates of each strain were used.
Project description:Background: Xylella fastidiosa, a Gram-negative fastidious bacterium, grows exclusively in the xylem of several plants, causing diseases such as citrus variegated chlorosis. As the xylem sap contains low concentrations of amino acids and other compounds, X. fastidiosa needs to cope with nitrogen limitation in its natural habitat. Results: In this work, we performed a whole-genome microarray analysis of the X. fastidiosa nitrogen starvation response. A time-course experiment (2, 8 and 12 hours) revealed many differentially expressed genes under nitrogen starvation, such as genes related to transport, nitrogen assimilation, amino acid biosynthesis, transcriptional regulation, and many genes encoding hypothetical proteins. In addition, a decrease in the expression levels of many genes involved in carbon metabolism and energy generation pathways was also observed. Comparison of gene expression profiles between the wild type strain and the rpoN null mutant allowed the identification of genes induced by nitrogen starvation in a σ54-dependent manner. A more complete picture of the σ54 regulon was achieved by combining the transcriptome data with an in silico search for potential σ54-dependent promoters, using a position weight matrix approach. One of these σ54-predicted binding sites, located upstream of the glnA gene (encoding a glutamine synthetase), was validated by primer extension assays, confirming that this gene has a σ54-dependent promoter and contains a predicted NtrC binding site. Conclusions: Together, these results show that nitrogen starvation causes intense changes in the X. fastidiosa transcriptome and some of these differentially expressed genes belong to the σ54 regulon.
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.