Structural insights into Xanthomonas campestris pv. campestris NAD biosynthesis via the NAM salvage pathway.

Nicotinamide phosphoribosyltransferase (NAMPT) plays an important role in the biosynthesis of nicotinamide adenine dinucleotide (NAD) via the nicotinamide (NAM) salvage pathway. While the structural biochemistry of eukaryote NAMPT has been well studied, the catalysis mechanism of prokaryote NAMPT at the molecular level remains largely unclear. Here, we demonstrated the NAMPT-mediated salvage pathway is functional in the Gram-negative phytopathogenic bacterium Xanthomonas campestris pv.

RNase D Is Involved in 5S rRNA Degradation and Exopolysaccharide Production in pv. .

Ribonucleases (RNases) play critical roles in RNA metabolism and are collectively essential for cell viability. However, most knowledge about bacterial RNases comes from the studies on ; very little is known about the RNases in plant pathogens. The crucifer black rot pathogen pv.

Extracellular Amylase Is Required for Full Virulence and Regulated by the Global Posttranscriptional Regulator RsmA in Pathovar .

As with many phytopathogenic bacteria, the virulence of pv. , the causal agent of black rot disease in cruciferous plants, relies on secretion of a suite of extracellular enzymes that includes cellulase (endoglucanase), pectinase, protease, and amylase. Although the role in virulence of a number of these enzymes has been assessed, the contribution of amylase to pv.

Genome-wide screen and functional analysis in Xanthomonas reveal a large number of mRNA-derived sRNAs, including the novel RsmA-sequester RsmU.

Although bacterial small noncoding RNAs (sRNAs) are known to play a critical role in various cellular processes, including pathogenesis, the identity and action of such sRNAs are still poorly understood in many organisms. Here we have performed a genome-wide screen and functional analysis of the sRNAs in Xanthomonas campestris pv. campestris (Xcc), an important phytopathogen.

A SAM-I riboswitch with the ability to sense and respond to uncharged initiator tRNA.

All known riboswitches use their aptamer to senese one metabolite signal and their expression platform to regulate gene expression. Here, we characterize a SAM-I riboswitch (SAM-I) from the Xanthomonas campestris that regulates methionine synthesis via the met operon. In vitro and in vivo experiments show that SAM-I controls the met operon primarily at the translational level in response to cellular S-adenosylmethionine (SAM) levels.

The crystal structure of the phytopathogenic bacterial sensor PcrK reveals different cytokinin recognition mechanism from the plant sensor AHK4.

Plant cytokinins (CKs) are essential for many central cellular processes and play important roles in the interaction between bacteria and plants. Perception of CK is executed by the CHASE domain in the histidine kinase sensors of a class of two-component regulatory systems. Despite advances in understanding the structural basis for CK perception by the sensor AHK4 in Arabidopsis, the molecular mechanism of CK binding by other sensors is unclear.

The Gram-negative phytopathogen Xanthomonas campestris pv. campestris employs a 5'UTR as a feedback controller to regulate methionine biosynthesis.

The synthesis of methionine is critical for most bacteria. It is known that cellular methionine has a feedback effect on the expression of met genes involved in de novo methionine biosynthesis. Previous studies revealed that Gram-negative bacteria control met gene expression at the transcriptional level by regulator proteins, while most Gram-positive bacteria regulate met genes at post-transcriptional level by RNA regulators (riboregulators) located in the 5'UTR of met genes.

The RNA chaperone Hfq is important for the virulence, motility and stress tolerance in the phytopathogen Xanthomonas campestris.

The RNA chaperone, Hfq, is known to play extensive roles in bacterial growth and development. More recently, it has been shown to be required for virulence in many human and animal bacterial pathogens. Despite these studies little is known about the role Hfq plays in phytopathogenic bacteria.

Establishment of an inducing medium for type III effector secretion in Xanthomonas campestris pv. campestris.

It is well known that the type III secretion system (T3SS) and type III (T3) effectors are essential for the pathogenicity of most bacterial phytopathogens and that the expression of T3SS and T3 effectors is suppressed in rich media but induced in minimal media and plants. To facilitate in-depth studies on T3SS and T3 effectors, it is crucial to establish a medium for T3 effector expression and secretion. Xanthomonas campestris pv.

High-resolution transcriptional analysis of the regulatory influence of cell-to-cell signalling reveals novel genes that contribute to Xanthomonas phytopathogenesis.

The bacterium Xanthomonas campestris is an economically important pathogen of many crop species and a model for the study of bacterial phytopathogenesis. In X. campestris, a regulatory system mediated by the signal molecule DSF controls virulence to plants.

Transcriptome profiling of Xanthomonas campestris pv. campestris grown in minimal medium MMX and rich medium NYG.

Xanthomonas campestris pathovar campestris (Xcc) is the causal agent of black rot disease in cruciferous plants worldwide. Although the complete genomes of several Xcc strains have been determined, the gene expression and regulation mechanisms in this pathogen are far from clear. In this work, transcriptome profiling of Xcc 8004 grown in MMX medium (minimal medium for Xanthomonas campestris) and NYG medium (peptone yeast glycerol medium) were investigated by RNA-Seq.

Effect of interactions between Mip and PrtA on the full extracellular protease activity of Xanthomonas campestris pathovar campestris.

Mip (macrophage infectivity potentiator) and Mip-like proteins have been demonstrated to be involved in virulence of several animal pathogens, but as yet none of their native bacterial targets has been identified. Our previous work demonstrated that the Mip-like protein found in the plant pathogen Xanthomonas campestris pv. campestris (Xcc) (hereafter called Mip(Xcc)) is also involved in virulence.

sRNA-Xcc1, an integron-encoded transposon- and plasmid-transferred trans-acting sRNA, is under the positive control of the key virulence regulators HrpG and HrpX of Xanthomonas campestris pathovar campestris.

sRNA-Xcc1 is a trans-acting sRNA recently identified from the plant pathogenic bacterium Xanthomonas campestris pathovar campestris (Xcc). Here, the phylogenetic distribution, predicted secondary structure and regulation of expression of sRNA-Xcc1 were analyzed. The analysis showed (1) a total 81 sRNA-Xcc1 homologs that are found in some bacterial strains that are taxonomically unrelated, belonging to the α-, β-, γ- and δ-proteobacteria (2) that some sRNA-Xcc1 homologs are located in a plasmid-borne transposon or near a transposase coding gene, (3) that sRNA-Xcc1 is encoded by a integron gene cassette in Xcc and sRNA-Xcc1 homologs occur in integron gene cassettes of some uncultured bacteria and (4) that sRNA-Xcc1 homologs have a highly conserved sequence motif and a stable consensus secondary structure.

Systematic mutagenesis of all predicted gntR genes in Xanthomonas campestris pv. campestris reveals a GntR family transcriptional regulator controlling hypersensitive response and virulence.

The GntR family is one of the most abundant and widely distributed groups of helix-turn-helix transcriptional regulators in bacteria. Six open reading frames in the genome of the plant pathogen Xanthomonas campestris pv. campestris were predicted to encode GntR regulators.

Identification of four novel small non-coding RNAs from Xanthomonas campestris pathovar campestris.

Background: In bacteria, small non-coding RNAs (sRNAs) have been recognized as important regulators of various cellular processes. Approximately 200 bacterial sRNAs in total have been reported. However, very few sRNAs have been identified from phytopathogenic bacteria.

Identification of six type III effector genes with the PIP box in Xanthomonas campestris pv. campestris and five of them contribute individually to full pathogenicity.

Xanthomonas campestris pv. campestris is the pathogen of black rot of cruciferous plants. The pathogenicity of the pathogen depends on the type III secretion system (T3SS) that translocates directly effector proteins into plant cells, where they play important roles in the molecular interaction between the pathogen and its hosts.

Glyceraldehyde-3-phosphate dehydrogenase of Xanthomonas campestris pv. campestris is required for extracellular polysaccharide production and full virulence.

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) plays an important role in glucose catabolism, converting glyceraldehyde 3-phosphates to 1,3-bisphosphoglycerates. Open reading frame (ORF) XC_0972 in the genome of Xanthomonas campestris pv. campestris (Xcc) strain 8004 is the only ORF in this strain annotated to encode a GAPDH.

An adenosine kinase exists in Xanthomonas campestris pathovar campestris and is involved in extracellular polysaccharide production, cell motility, and virulence.

Adenosine kinase (ADK) is a purine salvage enzyme and a typical housekeeping enzyme in eukaryotes which catalyzes the phosphorylation of adenosine to form AMP. Since prokaryotes synthesize purines de novo and no endogenous ADK activity is detectable in Escherichia coli, ADK has long been considered to be rare in bacteria. To date, only two prokaryotes, both of which are gram-positive bacteria, have been reported to contain ADK.

The Zur of Xanthomonas campestris is involved in hypersensitive response and positively regulates the expression of the hrp cluster via hrpX but not hrpG.

In bacteria, Zur is a key regulator for zinc homeostasis. Our previous work has shown that, in the phytopathogen Xanthomonas campestris pv. campestris, in addition to regulating zinc homeostasis, Zur is essential for full virulence.

A putative colR(XC1049)-colS(XC1050) two-component signal transduction system in Xanthomonas campestris positively regulates hrpC and hrpE operons and is involved in virulence, the hypersensitive response and tolerance to various stresses.

The ColR-ColS two-component signal transduction system was originally characterized as a regulatory system involved in the capacity of root-colonizing biocontrol bacterium Pseudomonas fluorescens to colonize plant roots. There are three pairs of putative colR-colS two-component regulatory systems annotated in the phytopathogen Xanthomonas campestris pathovar campestris. Mutational studies revealed that one of them, named colR(XC1049) and colS(XC1050), is a global regulatory system involved in various cellular processes, including virulence, hypersensitive response and stress tolerance.

DsbB is required for the pathogenesis process of Xanthomonas campestris pv. campestris.

The DsbA/DsbB oxidation pathway is one of the two pathways that catalyze disulfide bond formation of proteins in the periplasm of gram-negative bacteria. It has been demonstrated that DsbA is essential for multiple virulence factors of several animal bacterial pathogens. In this article, we present genetic evidence to show that the open reading frame XC_3314 encodes a DsbB protein that is involved in disulfide bond formation in periplasm of Xanthomonas campestris pv.