Role of <scp>DetR</scp> in defence is critical for virulence of <scp>X</scp>anthomonas oryzae pv. oryzae

Nguyen, Minh-Phuong; Park, Jongchan; Cho, Man-Ho; Lee, Sang‐Won

doi:10.1111/mpp.12305

Cited by 9 publications

(15 citation statements)

References 69 publications

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“…B). It is well known that diverse factors, including cell motility and EPS production, are associated with biofilm formation (Danese et al., ; Malamud et al., ; Mattick, ). In a previous study, the expression of proteins related to flagella and pili was positively regulated by Omp1X in a proteomic analysis and XooΔomp1X showed reduced flagella‐dependent motility (Park et al., ).…”

Section: Discussionmentioning

confidence: 99%

Deciphering the functions of the outer membrane porin OprBXo involved in virulence, motility, exopolysaccharide production, biofilm formation and stress tolerance in Xanthomonas oryzae pv. oryzae

Bae

Park

et al. 2018

Molecular Plant Pathology

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Xanthomonas oryzae pv. oryzae (Xoo) is a Gram-negative bacterium causing bacterial leaf blight disease in rice. Previously, proteomic analysis has shown that the outer membrane protein B in Xoo (OprBXo) is more abundant in the wildtype strain than is the outer membrane protein 1 in the Xoo (Omp1X) knockout mutant. OprBXo shows high homology with OprB, which has been well characterized as a carbohydrate-selective porin in X. citri ssp. citri and Pseudomonas species. However, the functions of OprBXo in Xoo have not yet been documented. To elucidate the functions of OprBXo, we generated the OprBXo-overexpressing mutant, Xoo(OprBXo), and the knockout mutant, XooΔoprBXo(EV). We found that the virulence and migration of Xoo(OprBXo), but not XooΔoprBXo(EV), were markedly reduced in rice. To postulate the mechanisms affected by OprBXo, comparative proteomic analysis was performed. Based on the results of proteomics, we employed diverse phenotypic assays to characterize the functions of OprBXo. Abnormal twitching motility and reduction in swarming motility were observed in Xoo(OprBXo). Moreover, Xoo(OprBXo) decreased, but XooΔoprBXo(EV) enhanced, exopolysaccharide production and biofilm formation. The chemotactic ability of XooΔoprBXo(EV) was dramatically lower than that of Xoo(EV) in the presence of glucose and xylose. Xoo(OprBXo) was resistant to sodium dodecylsulphate and hydrogen peroxide, but XooΔoprBXo(EV) was highly sensitive compared with Xoo(EV). Thus, OprBXo is not only essential for chemotaxis and stress tolerance, but also for motility, biofilm formation and exopolysaccharide production, which may contribute to the virulence of Xoo. These results will lead to new insights into the functions of a sugar-selective porin in Xoo.

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Section: Discussionmentioning

confidence: 99%

Deciphering the functions of the outer membrane porin OprBXo involved in virulence, motility, exopolysaccharide production, biofilm formation and stress tolerance in Xanthomonas oryzae pv. oryzae

Bae

Park

et al. 2018

Molecular Plant Pathology

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“…EPS production was determined as described previously [ 38 ]. To obtain maximum EPS, Xoo strains were adjusted to an OD 600 of 0.3, serially diluted (1000-fold), and grown in 5 mL PSB for 5 days.…”

Section: Methodsmentioning

confidence: 99%

“…The chromeazurol S (CAS) assay was used to examine siderophore production as described previously [ 38 ]. PSA-CAS plates were used as the iron-rich medium.…”

Section: Methodsmentioning

confidence: 99%

Elucidating Functions of FleQ in Xanthomonas oryzae pv. oryzae by Comparative Proteomic and Phenotypic Analyses

Bae

Park

et al. 2018

IJMS

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To acclimate to different environments, gene expression has to be controlled using diverse transcriptional activators. FleQ activates σ54-dependent transcription initiation and regulates flagellar biosynthesis and other mechanisms in several bacteria. Xanthomonas oryzae pv. oryzae (Xoo), which is a causal agent of bacterial leaf blight on rice, lacking FleQ loses swimming motility and virulence is not altered. However, other biological mechanisms related with FleQ in Xoo are unknown. In this study, we generated the FleQ-overexpressing strain, Xoo(FleQ), and knockout mutant, XooΔfleQ. To predict the mechanisms affected by FleQ, label-free shotgun comparative proteomics was carried out. Based on proteomic results, we performed diverse phenotypic assays. Xoo(FleQ) had reduced ability to elicit disease symptoms and exopolysaccharide production. Additionally, the ability of XooΔfleQ(EV) (empty vector) and Xoo(FleQ) to form biofilm was decreased. Swarming motility of XooΔfleQ(EV) was abolished, but was only reduced for Xoo(FleQ). Additionally, abnormal twitching motility was observed in both strains. Siderophore production of Xoo(FleQ) was enhanced in iron-rich conditions. The proteomic and phenotypic analyses revealed that FleQ is involved in flagellar-dependent motility and other mechanisms, including symptom development, twitching motility, exopolysaccharide production, biofilm formation, and siderophore production. Thus, this study provides fundamental information about a σ54-dependent transcription activator in Xoo.

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“…This disease causes severe losses and is found most predominantly in tropical Asian countries (Ferluga et al ., ). Xoo infects rice leaves mainly through hydathodes or wounds at the leaf tip, multiplies in the intercellular spaces and enters into xylem vessels (Nguyen et al ., ). Recently, this bacterium has been defined as one of the top 10 plant‐pathogenic bacteria in molecular plant pathology (Mansfield et al ., ).…”

Section: Introductionmentioning

confidence: 97%

Dissecting the virulence‐related functionality and cellular transcription mechanism of a conserved hypothetical protein in Xanthomonas oryzae pv. oryzae

Wang

Zhang

et al. 2018

Molecular Plant Pathology

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Hypothetical proteins without defined functions are largely distributed in all sequenced bacterial genomes. Understanding their potent functionalities is a basic demand for bacteriologists. Xanthomonas oryzae pv. oryzae (Xoo), the causal agent of bacterial leaf blight of rice, is one of the model systems for the study of molecular plant pathology. One-quarter of proteins in the genome of this bacterium are defined as hypothetical proteins, but their roles in Xoo pathogenicity are unknown. Here, we generated in-frame deletions for six hypothetical proteins selected from strain PXO99 and found that one of them (PXO_03177) is required for the full virulence of this strain. PXO_03177 is conserved in Xanthomonas, and is predicted to contain two domains relating to polysaccharide synthesis. However, we found that mutation of this gene did not affect the production or modification of extracellular polysaccharides (EPSs) and lipopolysaccharides (LPSs), two major polysaccharides produced by Xoo relating to its infection. Interestingly, we found that inactivation of PXO_03177 significantly impaired biofilm formation and tolerance to sodium dodecyl sulfate (SDS), both of which are considered to play key roles during Xoo infection in rice leaves. These findings thus enable us to define a function for PXO_03177 in the virulence of Xoo. Furthermore, we also found that the global regulator Clp controls the transcription of PXO_03177 by direct binding to its promoter region, presenting the first cellular regulatory pathway for the modulation of expression of this hypothetical protein gene. Our results provide reference information for PXO_03177 homologues in Xanthomonas.

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Role of DetR in defence is critical for virulence of Xanthomonas oryzae pv. oryzae

Cited by 9 publications

References 69 publications

Deciphering the functions of the outer membrane porin OprBXo involved in virulence, motility, exopolysaccharide production, biofilm formation and stress tolerance in Xanthomonas oryzae pv. oryzae

Deciphering the functions of the outer membrane porin OprBXo involved in virulence, motility, exopolysaccharide production, biofilm formation and stress tolerance in Xanthomonas oryzae pv. oryzae

Elucidating Functions of FleQ in Xanthomonas oryzae pv. oryzae by Comparative Proteomic and Phenotypic Analyses

Dissecting the virulence‐related functionality and cellular transcription mechanism of a conserved hypothetical protein in Xanthomonas oryzae pv. oryzae

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