rpfF Mutants of Xanthomonas oryzae pv. oryzae Are Deficient for Virulence and Growth Under Low Iron Conditions

2002 ◽  
Vol 15 (5) ◽  
pp. 463-471 ◽  
Author(s):  
Subhadeep Chatterjee ◽  
Ramesh V. Sonti
Keyword(s):  
Xanthomonas Campestris ◽  
Iron Supplementation ◽  
Extracellular Enzymes ◽  
Phenotypic Expression ◽  
Tetracycline Resistance ◽  
Extracellular Enzyme ◽  
Extracellular Polysaccharide ◽  
Xanthomonas Oryzae ◽  
Uptake System ◽  
Serious Disease

Xanthomonas oryzae pv. oryzae causes bacterial leaf blight, a serious disease of rice. In the related bacterium Xanthomonas campestris pv. campestris, the rpfF gene is involved in production of a diffusible extracellular factor (DSF) that positively regulates synthesis of virulence-associated functions like extracellular polysaccharide (EPS) and extracellular enzymes. Transposon insertions in the rpfF homolog of X. oryzae pv. oryzae are deficient for virulence and production of a DSF but are proficient for EPS and extracellular enzyme production. The rpfF X. oryzae pv. oryzae mutants exhibit an unusual tetracycline susceptibility phenotype in which exogenous iron supplementation is required for phenotypic expression of a tetracycline resistance determinant that is encoded on an introduced plasmid. The rpfF X. oryzae pv. oryzae mutants also overproduce one or more siderophores and exhibit a growth deficiency under low iron conditions as well as in the presence of reducing agents that are expected to promote the conversion of Fe+3 to Fe+2. Exogenous iron supplementation promotes migration of rpfF X. oryzae pv. oryzae mutants in rice leaves. The results suggest that rpfF may be involved in controlling an iron-uptake system of X. oryzae pv. oryzae and that an inability to cope with the conditions of low iron availability in the host may be the reason for the virulence deficiency of the rpfF X. oryzae pv. oryzae mutants.

scholarly journals Stationary-Phase Variation Due to Transposition of Novel Insertion Elements in Xanthomonas oryzae pv. oryzae

2000 ◽  
Vol 182 (17) ◽  
pp. 4797-4802 ◽  
Author(s):  
R. Rajeshwari ◽  
R. V. Sonti
Keyword(s):  
Stationary Phase ◽  
Phase Variation ◽  
Pcr Amplification ◽  
Extracellular Polysaccharide ◽  
Xanthomonas Oryzae ◽  
Is Elements ◽  
Large Numbers ◽  
Insertion Elements ◽  
Multiple Copies ◽  
Serious Disease

ABSTRACT Xanthomonas oryzae pv. oryzae causes bacterial leaf blight, a serious disease of rice. Spontaneous mutants which are deficient for virulence and extracellular polysaccharide (Eps) production accumulate in large numbers in stationary-phase cultures of this bacterium, a phenomenon which we have called stationary-phase variation. A clone (pSD1) carrying the Eps biosynthetic gene (gum) cluster of X. oryzae pv. oryzae restored Eps production and virulence to several spv (for stationary-phase variation) mutants. Data from localized recombination analysis, Southern hybridization, PCR amplification, and sequence analysis showed that the mutations are due to insertion of either one of two novel endogenous insertion sequence (IS) elements, namely, ISXo1 and ISXo2, into gumM, the last gene of the gum gene cluster. The results of Southern analysis indicate the presence of multiple copies of both IS elements in the genome of X. oryzae pv. oryzae. These results demonstrate the role of IS elements in stationary-phase variation in X. oryzae pv. oryzae.

scholarly journals Synthesis of Extracellular Polysaccharide, Extracellular Enzymes, and Xanthomonadin in Xanthomonas campestris: Evidence for the Involvement of Two Intercellular Regulatory Signals

1998 ◽  
Vol 11 (1) ◽  
pp. 68-70 ◽  
Author(s):  
Alan R. Poplawsky ◽  
Wesley Chun ◽  
Holly Slater ◽  
Michael J. Daniels ◽  
J. Maxwell Dow
Keyword(s):  
Xanthomonas Campestris ◽  
Extracellular Enzymes ◽  
Extracellular Polysaccharide ◽  
Transcriptional Unit ◽  
Intercellular Signaling ◽  
Signaling Systems ◽  
Mutant Strains ◽  
Diffusible Factor

In previous work, the pigB transcriptional unit of Xanthomonas campestris was implicated in the generation of a diffusible factor (DF) that regulates xanthomonadin and extracellular polysaccharide (EPS) production. Similarly, the rpfF and rpfB genes were implicated in the generation of a diffusible factor (DSF) that regulates the production of extracellular enzymes and EPS. In this study, extracel-lular cross-feeding studies with rpfF and pigB mutant strains provided evidence for the existence of two separate intercellular signaling systems with overlapping roles in the regulation of EPS production.

scholarly journals The RpfB-Dependent Quorum Sensing Signal Turnover System Is Required for Adaptation and Virulence in Rice Bacterial Blight Pathogen Xanthomonas oryzae pv. oryzae

2016 ◽  
Vol 29 (3) ◽  
pp. 220-230 ◽  
Author(s):  
Xing-Yu Wang ◽  
Lian Zhou ◽  
Jun Yang ◽  
Guang-Hai Ji ◽  
Ya-Wen He
Keyword(s):  
Quorum Sensing ◽  
Bacterial Blight ◽  
Xanthomonas Campestris ◽  
Deletion Mutant ◽  
Extracellular Polysaccharide ◽  
Xanthomonas Oryzae ◽  
Rice Bacterial Blight ◽  
Double Deletion ◽  
Diffusible Signal Factor ◽  
Bacterial Blight Pathogen

Xanthomonas oryzae pv. oryzae, the bacterial blight pathogen of rice, produces diffusible signal factor (DSF) family quorum sensing signals to regulate virulence. The biosynthesis and perception of DSF family signals require components of the rpf (regulation of pathogenicity factors) cluster. In this study, we report that RpfB plays an essential role in DSF family signal turnover in X. oryzae pv. oryzae PXO99A. The production of DSF family signals was boosted by deletion of the rpfB gene and was abolished by its overexpression. The RpfC/RpfG-mediated DSF signaling system negatively regulates rpfB expression via the global transcription regulator Clp, whose activity is reversible in the presence of cyclic diguanylate monophosphate. These findings indicate that the DSF family signal turnover system in PXO99A is generally consistent with that in Xanthomonas campestris pv. campestris. Moreover, this study has revealed several specific roles of RpfB in PXO99A. First, the rpfB deletion mutant produced high levels of DSF family signals but reduced extracellular polysaccharide production, extracellular amylase activity, and attenuated pathogenicity. Second, the rpfB/rpfC double-deletion mutant was partially deficient in xanthomonadin production. Taken together, the RpfB-dependent DSF family signal turnover system is a conserved and naturally presenting signal turnover system in Xanthomonas spp., which plays unique roles in X. oryzae pv. oryzae adaptation and pathogenesis.

scholarly journals The Zinc Uptake Regulator Zur Is Essential for the Full Virulence of Xanthomonas campestris pv. campestris

2005 ◽  
Vol 18 (7) ◽  
pp. 652-658 ◽  
Author(s):  
Dong-Jie Tang ◽  
Xiang-Jiang Li ◽  
Yong-Qiang He ◽  
Jia-Xun Feng ◽  
Baoshan Chen ◽  
...  
Keyword(s):  
Type Strain ◽  
Xanthomonas Campestris ◽  
Wild Type Strain ◽  
Extracellular Polysaccharide ◽  
Zinc Uptake ◽  
Zinc Homeostasis ◽  
Uptake System ◽  
Rich Medium ◽  
Wild Type ◽  
Xanthomonas Campestris Pv Campestris

Zur is a regulator of the high-affinity zinc uptake system in many bacteria. In Xanthomonas campestris pv. campestris 8004, a putative protein encoded by the open reading frame designated as XC1430 shows 42% amino acid similarity with the Zur of Escherichia coli. An XC1430-disrupted mutant 1430nk was constructed by homologous suicide plasmid integration. 1430nk failed to grow in rich medium supplemented with Zn2+ at a concentration of 400 μM and in nonrich medium supplemented with Zn2+ at a concentration of 110 μM, whereas the wild-type strain grew well in the same conditions. In rich medium with 400 μM Zn2+, 1430nk accumulated significantly more Zn2+ than the wild-type strain. 1430nk showed a reduction in virulence on the host plant Chinese radish (Raphanus sativus L. var. radiculus Pers.) and produced less extracellular polysaccharide (EPS) than did the wild-type strain in the absence of added zinc. These results revealed that XC1430 is a functional member of the Zur regulator family that controls zinc homeostasis, EPS production, and virulence in X. campestris pv. campestris.

scholarly journals PhyA, a Secreted Protein of Xanthomonas oryzae pv. oryzae, Is Required for Optimum Virulence and Growth on Phytic Acid as a Sole Phosphate Source

2003 ◽  
Vol 16 (11) ◽  
pp. 973-982 ◽  
Author(s):  
Subhadeep Chatterjee ◽  
Rajan Sankaranarayanan ◽  
Ramesh V. Sonti
Keyword(s):  
Phytic Acid ◽  
Xanthomonas Campestris ◽  
Xanthomonas Oryzae ◽  
Bacillus Species ◽  
Active Site Residues ◽  
Significant Similarity ◽  
Reading Frame ◽  
Predicted Signal Peptide ◽  
Serious Disease ◽  
Phosphate Source

Xanthomonas oryzae pv. oryzae causes bacterial leaf blight, a serious disease of rice. We have identified a novel virulence deficient mutant (BXO1691) of X. oryzae pv. oryzae that has a Tn5 insertion in an open reading frame (phyA; putative phytase A) encoding a 373-amino acid (aa) protein containing a 28-aa predicted signal peptide. Extracellular protein profiles revealed that a 38-kDa band is absent in phyA mutants as compared with phyA+ strains. A BLAST search with phyA and its deduced polypeptide sequence indicated significant similarity with conserved hypothetical proteins in Xanthomonas axonopodis pv. citri and Xanthomonas campestris pv. campestris and limited homology to secreted phytases of Bacillus species. Homology modeling with a Bacillus phytase as the template suggests that the PhyA protein has a similar six-bladed β-propeller architecture and exhibits conservation of certain critical active site residues. Phytases are enzymes that are involved in degradation of phytic acid (inositol hexaphosphate), a stored form of phosphate in plants. The phyA mutants exhibit a growth deficiency in media containing phytic acid as a sole phosphate source. Exogenous phosphate supplementation promotes migration of phyA X. oryzae pv. oryzae mutants in rice leaves. These results suggest that the virulence deficiency of phyA mutants is, at least in part, due to inability to use host phytic acid as a source of phosphate. phyA-like genes have not been previously reported to be involved in the virulence of any plant pathogenic bacterium.

Virulence deficiency caused by a transposon insertion in the purH gene of Xanthomonas oryzae pv. oryzae

2005 ◽  
Vol 51 (7) ◽  
pp. 575-581 ◽  
Author(s):  
Subhadeep Chatterjee ◽  
Ramesh V Sonti
Keyword(s):  
Xanthomonas Campestris ◽  
Pathogenic Bacteria ◽  
Minimal Medium ◽  
Pathogen Resistance ◽  
Xanthomonas Oryzae ◽  
Chromosomal Dna ◽  
Transposon Insertion ◽  
Growth Deficiency ◽  
Related Plant ◽  
Serious Disease

Xanthomonas oryzae pv. oryzae causes bacterial leaf blight, a serious disease of rice. We have identified a Tn5-induced virulence-deficient mutant (BXO1704) of X. oryzae pv. oryzae. The BXO1704 mutant exhibited growth deficiency in minimal medium but was proficient in inducing a hypersensitive response in a non-host tomato plant. Sequence analysis of the chromosomal DNA flanking the Tn5 insertion indicated that the Tn5 insertion is in the purH gene, which is highly homologous to purH genes of other closely related plant pathogenic bacteria Xanthomonas axonopodis pv. citri and Xanthomonas campestris pv. campestris. Purine supplementation reversed the growth deficiency of BXO1704 in minimal medium. These results suggest that the virulence deficiency of BXO1704 may be due to the inability to use sufficient purine in the host.Key words: auxotroph, plant pathogen, resistance.

scholarly journals Mutants of Xanthomonas oryzae pv. oryzae Deficient in General Secretory Pathway Are Virulence Deficient and Unable to Secrete Xylanase

2000 ◽  
Vol 13 (4) ◽  
pp. 394-401 ◽  
Author(s):  
Suvendra K. Ray ◽  
R. Rajeshwari ◽  
Ramesh V. Sonti
Keyword(s):  
Xanthomonas Campestris ◽  
Secretory Pathway ◽  
Genomic Library ◽  
Xanthomonas Oryzae ◽  
Enzyme Assays ◽  
Specific Primers ◽  
Xylanase Production ◽  
Protein Secretion System ◽  
Serious Disease ◽  
Xanthomonas Campestris Pv Campestris

Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial leaf blight, a serious disease of rice. A virulence- and xylanase-deficient mutant of Xoo was isolated following ethyl methane sulfonate (EMS) mutagenesis. A cosmid clone that restored virulence and xylanase secretion was obtained from a genomic library by functional complementation. Trans-poson mutagenesis and marker exchange studies revealed genes on the cloned DNA that were required for xylanase production and virulence. Sequence analysis with trans-poson-specific primers revealed that these genes were homologues of xps F and xps D, which encode components of a protein secretion system in Xanthomonas campestris pv. campestris. Enzyme assays showed xylanase accumulation in the periplasmic space and cytoplasm of the xps F mutant and the complementing clone restored transport to the extracellular space.

Characteristics of stationary-phase variation affecting virulence in Xanthomonas oryzae pv. oryzae

1997 ◽  
Vol 43 (9) ◽  
pp. 862-867 ◽  
Author(s):  
R. Rajeshwari ◽  
J. Yashitola ◽  
R. V. Sonti ◽  
A. P. K. Reddy
Keyword(s):  
Stationary Phase ◽  
Phase Variation ◽  
Extracellular Polysaccharide ◽  
Xanthomonas Oryzae ◽  
Mutant Phenotype ◽  
Bacterial Leaf Blight ◽  
Wild Type ◽  
Serious Disease ◽  
The Stability

Xanthomonas oryzae pv. oryzae is the causal agent of bacterial leaf blight, a serious disease of rice. Spontaneous loss of virulence in X. oryzae pv. oryzae is associated with mutants that produce reduced levels of extracellular polysaccharide. Evidence is presented that these mutants accumulate in long-term stationary phase cultures but are not obtained from exponentially growing cultures. A number of independent spv (stationary-phase variation) mutants have been isolated and characterized. These mutants differ from each other with respect to the stability of the mutant phenotype, extent of loss of virulence, ability to outcompete wild type cells in stationary-phase cocultures, and hypersensitivity to hydrogen peroxide.Key words: stationary-phase variation, spontaneous loss of virulence, Xanthomonas oryzae.

scholarly journals The lolB gene in Xanthomonas campestris pv. campestris is required for bacterial attachment, stress tolerance, and virulence

2022 ◽  
Vol 22 (1) ◽  
Author(s):  
Chao-Tsai Liao ◽  
Chih-En Li ◽  
Hsiao-Ching Chang ◽  
Chien-Hui Hsu ◽  
Ying-Chuan Chiang ◽  
...  
Keyword(s):  
Stress Tolerance ◽  
Outer Membrane ◽  
Xanthomonas Campestris ◽  
Extracellular Enzymes ◽  
Physiological Role ◽  
Extracellular Enzyme ◽  
Bacterial Attachment ◽  
Expression Of Genes ◽  
Functional Understanding

Abstract Background Xanthomonas campestris pv. campestris (Xcc) is a Gram-negative bacterium that can cause black rot disease in crucifers. The lipoprotein outer membrane localization (Lol) system is involved in the lipoprotein sorting to the outer membrane. Although Xcc has a set of annotated lol genes, there is still little known about the physiological role in this phytopathogen. In this study, we aimed to characterize the role of LolB of Xcc in bacterial attachment, stress tolerance, and virulence. Results To characterize the role of LolB, lolB mutant was constructed and phenotypic evaluation was performed. The lolB mutant revealed reductions in bacterial attachment, extracellular enzyme production, and virulence. Mutation of lolB also resulted in reduced tolerance to a myriad of stresses, including heat and a range of membrane-perturbing agents. Trans-complementation of lolB mutant with intact lolB gene reverted these altered phenotypes to the wild-type levels. From subsequent reporter assay and reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) analysis, the expression of genes that encode the major extracellular enzymes and the stress-related proteins was reduced after lolB mutation. Conclusions The results in this work contribute to the functional understanding of lolB in Xanthomonas for the first time, and provide new insights into the function of lolB in bacteria.

scholarly journals Extracellular hydrolytic enzyme production by proteolytic bacteria from the Antarctic

2013 ◽  
Vol 34 (3) ◽  
pp. 253-267 ◽  
Author(s):  
Mauro Tropeano ◽  
Susana Vázquez ◽  
Silvia Coria ◽  
Adrián Turjanski ◽  
Daniel Cicero ◽  
...  
Keyword(s):  
Extracellular Enzymes ◽  
Restriction Analysis ◽  
Hydrolytic Enzyme ◽  
Hydrolytic Enzymes ◽  
Extracellular Enzyme ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Potter Cove ◽  
Starting Point ◽  
Dna Restriction

AbstractCold−adapted marine bacteria producing extracellular hydrolytic enzymes are important for their industrial application and play a key role in degradation of particulate organic matter in their natural environment. In this work, members of a previously−obtained protease−producing bacterial collection isolated from different marine sources from Potter Cove (King George Island, South Shetlands) were taxonomically identified and screened for their ability to produce other economically relevant enzymes. Eighty−eight proteolytic bacterial isolates were grouped into 25 phylotypes based on their Amplified Ribosomal DNA Restriction Analysis profiles. The sequencing of the 16S rRNA genes from representative isolates of the phylotypes showed that the predominant culturable protease−producing bacteria belonged to the class Gammaproteobacteria and were affiliated to the genera Pseudomonas, Shewanella, Colwellia, and Pseudoalteromonas, the latter being the predominant group (64% of isolates). In addition, members of the classes Actinobacteria, Bacilli and Flavobacteria were found. Among the 88 isolates screened we detected producers of amylases (21), pectinases (67), cellulases (53), CM−cellulases (68), xylanases (55) and agarases (57). More than 85% of the isolates showed at least one of the extracellular enzymatic activities tested, with some of them producing up to six extracellular enzymes. Our results confirmed that using selective conditions to isolate producers of one extracellular enzyme activity increases the probability of recovering bacteria that will also produce additional extracellular enzymes. This finding establishes a starting point for future programs oriented to the prospecting for biomolecules in Antarctica.

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