scholarly journals The diffusible signal factor synthase, RpfF, in Xanthomonas oryzae pv. oryzae is required for the maintenance of membrane integrity and virulence

2021 ◽  
Author(s):  
Prashantee Singh ◽  
Raj Kumar Verma ◽  
Subhadeep Chatterjee
Keyword(s):  
Membrane Integrity ◽  
Xanthomonas Oryzae ◽  
Diffusible Signal Factor

scholarly journals Identification and Characterization of a Novel Gene, hshB, in Xanthomonas oryzae pv. oryzicola Co-Regulated by Quorum Sensing and clp

2012 ◽  
Vol 102 (3) ◽  
pp. 252-259 ◽  
Author(s):  
Yancun Zhao ◽  
Guoliang Qian ◽  
Jiaqin Fan ◽  
Fangqun Yin ◽  
Yijin Zhou ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Extracellular Polysaccharide ◽  
Bioinformatic Analysis ◽  
Xanthomonas Oryzae ◽  
Pcr Analysis ◽  
Homologous Gene ◽  
Upstream Gene ◽  
Novel Gene ◽  
Putative Signal Peptide ◽  
Diffusible Signal Factor

Virulence factors of Xanthomonas oryzae pv. oryzicola, the causal agent of bacterial leaf streak in rice, are regulated by a diffusible signal factor (DSF)-dependent quorum-sensing (QS) system. In this study, a novel pathogenicity-related gene, Xoryp_010100018570 (named hshB), of X. oryzae pv. oryzicola was characterized. hshB encodes a hydrolase with a putative signal peptide, which is a homolog of imidazolonepropionase. Bioinformatic analysis showed that hshB is relatively conserved in the genus Xanthomonas but the homologous gene of hshB was not found in X. oryzae pv. oryzae. Reverse-transcription polymerase chain reaction (PCR) analysis showed that hshB and its upstream gene, Xoryp_010100018565 (named hshA), are co-transcribed in X. oryzae pv. oryzicola. Subsequent experimental results indicated that mutation of hshB remarkably impaired the virulence, extracellular protease activity, extracellular polysaccharide production, growth in minimal medium, and resistance to oxidative stress and bismerthiazol of X. oryzae pv. oryzicola. Mutation of clp, encoding a global regulator, resulted in similar phenotypes. Real-time PCR assays showed that hshB transcription is positively regulated by clp and DSF, and induced by poor nutrition. Our study not only found a novel gene hshB regulated by DSF-dependent QS system and clp but also showed that hshB was required for virulence of X. oryzae pv. oryzicola.

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 xrvA gene of Xanthomonas oryzae pv. oryzae, encoding an H-NS-like protein, regulates virulence in rice

Microbiology ◽  
2009 ◽  
Vol 155 (9) ◽  
pp. 3033-3044 ◽  
Author(s):  
Jia-Xun Feng ◽  
Zhi-Zhong Song ◽  
Cheng-Jie Duan ◽  
Shuai Zhao ◽  
Ying-Qiao Wu ◽  
...  
Keyword(s):  
Bacterial Blight ◽  
Extracellular Polysaccharide ◽  
Xanthomonas Oryzae ◽  
Northern Hybridization ◽  
Wild Type ◽  
Glycogen Accumulation ◽  
Diffusible Signal Factor ◽  
In The Wild ◽  
Oil Plant ◽  
Blight Disease

Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial blight disease in rice, one of the most serious rice diseases. The xrvA gene from Xoo strain 13751 encodes a protein containing a histone-like nucleoid-structuring protein (H-NS) domain. The expression of xrvA in strain 13751 was enhanced in XOM2 minimal medium. Mutation of the xrvA gene of strain 13751 led to a significant reduction in virulence in the host plant rice, a delayed hypersensitive response in the nonhost castor-oil plant, a decrease in extracellular polysaccharide and diffusible signal factor production, and an increase in intracellular glycogen accumulation. Northern hybridization analyses revealed that the virulence-associated genes hrpG, hrpX, rpfC, rpfF, rpfG and gumB were downregulated in the xrvA mutant compared to the wild-type and complemented strains. Interestingly, increase of copy number of xrvA in the wild-type strain 13751 resulted in a strain showing similar phenotypes as the xrvA mutant and a reduction of the expression of gumB, hrpX, rpfC, rpfF and rpfG. These findings indicate that the xrvA gene, which is highly conserved in the sequenced strains of Xanthomonas, encodes an important regulatory factor for the virulence of Xoo.

scholarly journals Atypical Regulation of Virulence-Associated Functions by a Diffusible Signal Factor in Xanthomonas oryzae pv. oryzae

2012 ◽  
Vol 25 (6) ◽  
pp. 789-801 ◽  
Author(s):  
Rikky Rai ◽  
Manish Ranjan ◽  
Binod B. Pradhan ◽  
Subhadeep Chatterjee
Keyword(s):  
Biofilm Formation ◽  
Bacterial Blight ◽  
Hydrolytic Enzymes ◽  
Xanthomonas Oryzae ◽  
Enzymatic Assays ◽  
Expression Of Genes ◽  
Associated Functions ◽  
Diffusible Signal Factor ◽  
Bacterial Blight Pathogen ◽  
Transcriptional Changes

In Xanthomonas oryzae pv. oryzae, the bacterial blight pathogen of rice, a secreted fatty acid signaling molecule known as diffusible signal factor (DSF) is required for virulence and growth on low-iron medium. To identify other virulence-associated traits that are regulated by DSF in this pathogen, we have performed microarray analysis of transcriptional changes between the wild type and DSF-deficient mutants of X. oryzae pv. oryzae. Expression of genes that encode secreted hydrolytic enzymes, motility, and chemotaxis functions are negatively regulated by DSF while functions involved in adhesion and biofilm formation are positively regulated. Enzymatic assays for hydrolytic enzymes as well as assays for chemotaxis, motility, attachment, and biofilm formation corroborate these findings. These results demonstrate that, in X. oryzae pv. oryzae, DSF-mediated cell-to-cell signaling coordinates transition from solitary to biofilm lifestyle by promoting expression of attachment functions and negatively regulating expression of motility functions. This is in contrast to X. campestris pv. campestris, a pathogen of crucifers, wherein the DSF system positively regulates motility functions and negatively regulates biofilm formation. These results indicate that virulence-associated functions can be regulated in a completely contrasting fashion by the same signaling system in very closely related bacteria.

scholarly journals Identification and Characterization of Two Novel DSF-Controlled Virulence-Associated Genes Within the nodB-rhgB Locus of Xanthomonas oryzae pv. oryzicola Rs105

2015 ◽  
Vol 105 (5) ◽  
pp. 588-596 ◽  
Author(s):  
Zhiwei Song ◽  
Yancun Zhao ◽  
Xingyang Zhou ◽  
Guichun Wu ◽  
Yuqiang Zhang ◽  
...  
Keyword(s):  
Extracellular Polysaccharide ◽  
Xanthomonas Oryzae ◽  
In Planta ◽  
Inoculation Density ◽  
Xanthomonas Species ◽  
Diffusible Signal Factor ◽  
Visible Effect ◽  
Extracellular Protease Activity ◽  
Epiphytic Survival

Xanthomonas oryzae pv. oryzicola and X. oryzae pv. oryzae are two pathovars of X. oryzae that cause leaf streak and blight in rice, respectively. These two bacterial pathogens cause different disease symptoms by utilizing different infection sites on rice. Compared with X. oryzae pv. oryzae, the molecular virulence mechanism of X. oryzae pv. oryzicola remains largely unknown. Previously, we identified a unique diffusible signal factor (DSF)-controlled virulence-related gene (hshB) in X. oryzae pv. oryzicola Rs105 located in the nodB-rghB locus, which is absent in X. oryzae pv. oryzae PXO99A. In the present study, we identified two additional genes within this locus (hshA and hshC) that were unique to X. oryzae pv. oryzicola Rs105 compared with X. oryzae pv. oryzae PXO99A, and we found that the transcription of these genes was regulated by DSF signaling in X. oryzae pv. oryzicola. The mutation of these genes impaired the virulence of the wild-type Rs105 when using a low inoculation density of X. oryzae pv. oryzicola. In contrast to hshB, the mutation of these genes did not have any visible effect on characterized virulence-related functions, including in vitro growth, extracellular polysaccharide production, extracellular protease activity, and antioxidative ability. However, we found that mutation of hshA or hshC significantly reduced the in planta growth ability and epiphytic survival level of X. oryzae pv. oryzicola cells, which was the probable mechanisms of involvement of these two genes in virulence. Collectively, our studies of X. oryzae pv. oryzicola have identified two novel DSF-controlled virulence-associated genes (hshA and hshC), which will add to our understanding of the regulatory mechanisms of conserved DSF virulence signaling in Xanthomonas species.

scholarly journals OryR Is a LuxR-Family Protein Involved in Interkingdom Signaling between Pathogenic Xanthomonas oryzae pv. oryzae and Rice

2008 ◽  
Vol 191 (3) ◽  
pp. 890-897 ◽  
Author(s):  
Sara Ferluga ◽  
Vittorio Venturi
Keyword(s):  
Quorum Sensing ◽  
Virulence Gene ◽  
Homoserine Lactone ◽  
Xanthomonas Oryzae ◽  
Signal Molecule ◽  
Family Protein ◽  
Diffusible Signal Factor ◽  
Important Regulator ◽  
Interkingdom Communication ◽  
Target Promoters

ABSTRACT Xanthomonas oryzae pv. oryzae, the causal agent of bacterial leaf blight in rice, contains a regulator that is encoded in the genome, designated OryR, which belongs to the N-acyl homoserine lactone (AHL)-dependent quorum-sensing LuxR subfamily of proteins. However, we previously reported that X. oryzae pv. oryzae does not make AHLs and does not possess a LuxI-family AHL synthase and that the OryR protein is solubilized by a compound present in rice. In this study we obtained further evidence that OryR interacts with a rice signal molecule (RSM) and that the OryR concentration increases when rice is infected with X. oryzae pv. oryzae. We also describe three OryR target promoters which are regulated differently: (i) the neighboring proline iminopeptidase (pip) virulence gene, which is positively regulated by OryR in the presence of the RSM; (ii) the oryR promoter, which is negatively autoregulated independent of the RSM; and (iii) the 1,4-β-cellobiosidase cbsA gene, which is positively regulated by OryR independent of the RSM. We also found that the RSM for OryR is small, is not related to AHLs, and is not able to activate the broad-range AHL biosensor Agrobacterium tumefaciens NT1(pZLQR). Furthermore, OryR does not regulate production of the quorum-sensing diffusible signal factor present in the genus Xanthomonas. Therefore, OryR has unique features and is an important regulator involved in interkingdom communication between the host and the pathogen.

scholarly journals epv, Encoding a Hypothetical Protein, Is Regulated by DSF-Mediating Quorum Sensing as Well as Global Regulator Clp and Is Required for Optimal Virulence in Xanthomonas oryzae pv. oryzicola

2012 ◽  
Vol 102 (9) ◽  
pp. 841-847 ◽  
Author(s):  
Guoliang Qian ◽  
Yanbing Zhang ◽  
Yijin Zhou ◽  
Chunhui Liu ◽  
Yancun Zhao ◽  
...  
Keyword(s):  
Phosphoglycerate Kinase ◽  
Extracellular Polysaccharide ◽  
Hypothetical Protein ◽  
Hypersensitive Reaction ◽  
Xanthomonas Oryzae ◽  
Related Gene ◽  
Global Regulator ◽  
Gene Encoding ◽  
Associated Functions ◽  
Diffusible Signal Factor

Xanthomonas oryzae pv. oryzicola causes bacterial leaf streak in rice, a destructive disease worldwide. In this study, six putative hypothetical secreted proteins, which were absent in X. oryzae pv. oryzae, were detected from X. oryzae pv. oryzicola strain BLS256. Disruption-based mutagenesis study revealed that one of them, Xoc_15235, named as extracellular polysaccharide and virulence-related gene (epv), was required for the optimal virulence in host rice but not for the induction of a hypersensitive reaction in nonhost tobacco. Sequence analysis revealed that epv was highly conserved in Xanthomonas spp. (except X. oryzae pv. oryzae). In-frame deletion of epv in X. oryzae pv. oryzicola dramatically impaired pathogen virulence and extracellular polysaccharide (EPS) production, one of the important known virulence-associated functions in Xanthomonas spp. Quantitative real-time reverse-transcription polymerase chain reaction showed that expression of both gumB (a gene encoding exopolysaccharide xanthan biosynthesis export protein) and a known virulence-related gene, pgk (encoding phosphoglycerate kinase), were obviously reduced in the epv-deletion mutant compared with the wild-type strain Rs105. In addition, we observed that epv was positively regulated by both diffusible signal factor and global regulator Clp in X. oryzae pv. oryzicola. Taken together, the novel roles and genetics of epv of X. oryzae pv. oryzicola in the EPS production and virulence were investigated for the first time.

Reversal of cardiomyopathy resulting from prenatal exposure to ethanol

1984 ◽  
Vol 42 ◽  
pp. 716-717
Author(s):  
C. Uphoff ◽  
C. Nyquist-Battie
Keyword(s):  
Prenatal Exposure ◽  
Heart Development ◽  
Membrane Integrity ◽  
Ethanol Exposure ◽  
Prenatal Ethanol Exposure ◽  
Pathological Changes ◽  
Prenatally Exposed ◽  
Inner Mitochondrial Membrane ◽  
Fetal Alcohol ◽  
Newborn Mice

Fetal Alcohol Syndrone (FAS) is a syndrome with characteristic abnormalities resulting from prenatal exposure to ethanol. In many children with FAS syndrome gross pathological changes in the heart are seen with septal defects the most prevalent abnormality recorded. Few studies in animal models have been performed on the effects of ethanol on heart development. In our laboratory, it has been observed that prenatal ethanol exposure of Swiss albino mice results in abnormal cardiac muscle ultrastructure when mice were examined at birth and compared to pairfed and normal controls. Fig. 1 is an example of the changes that are seen in the ethanol-exposed animals. These changes include enlarged mitochondria with loss of inner mitochondrial membrane integrity and loss of myofibrils. Morphometric analysis substantiated the presence of these alterations from normal cardiac ultrastructure. The present work was undertaken to determine if the pathological changes seen in the newborn mice prenatally exposed to ethanol could be reversed with age and abstinence.

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