A two‐component regulatory system VfmIH modulates multiple virulence traits in <i>Dickeya zeae</i>

Lv, Minna; Hu, Ming; Jiang, Zide; Zhang, Lian-Hui; Zhou, Jianuan

doi:10.1111/mmi.14233

Cited by 33 publications

(82 citation statements)

References 51 publications

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“…Furthermore, several regulatory mechanisms associated with c-di-GMP turnover have been implicated in D. zeae virulence from our previous findings; specifically, the two-component system proteins VfmIH and a global transcriptional regulator, SlyA, were reported to regulate some key c-di-GMP turnover enzymes at the transcriptional level, including the primary DGC14945 enzyme (14,16). The AHL quorum sensing signal as well as host-pathogen communication through putrescine signaling were reported to mainly regulate flagellar motility and biofilm formation (17,18).…”

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confidence: 75%

“…In addition, several regulatory mechanisms associated with D. zeae virulence have been uncovered in recent years, including the transcription factors SlyA and Fis (14,15); a two-component regulatory system, VfmHI (16); an acyl-homoserine lactone (AHL)mediated quorum sensing (QS) system (17); a polyamine-mediated host-pathogen communication system (18); and the bacterial second messenger cyclic di-GMP (c-di-GMP) (19). These findings present both a framework and useful clues for dissecting the molecular mechanisms and signaling networks by which D. zeae modulates its physiology and virulence.…”

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confidence: 99%

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Systematic Analysis of c-di-GMP Signaling Mechanisms and Biological Functions in Dickeya zeae EC1

Chen

Zhou

et al. 2020

mBio

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Dickeya zeae is an important and aggressive bacterial phytopathogen that can cause substantial economic losses in banana and rice plantations. We previously showed that c-di-GMP signaling proteins (cyclases/phosphodiesterases) in D. zeae strain EC1 play a significant role in the bacterial sessile-to-motile transition. To determine whether there is any synergistic effect among these c-di-GMP signaling proteins, we prepared a series of mutant strains by generating consecutive in-frame deletions of the genes encoding diguanylate cyclases (which make c-di-GMP) and phosphodiesterases (which break down c-di-GMP), respectively, using EC1 as a parental strain. The results showed that the complete deletion of all the putative diguanylate cyclases resulted in significantly increased bacterial motility and abrogated biofilm formation but did not appear to affect pathogenicity and virulence factor production. In contrast, the deletion of all the c-di-GMP phosphodiesterase genes disabled motility and prevented the invasion of EC1 into rice seeds. By measuring the c-di-GMP concentrations and swimming motility of all the mutants, we propose that c-di-GMP controlled swimming behavior through a multitiered program in a c-di-GMP concentration-dependent manner, which could be described as an L-shaped regression curve. These features are quite different from those that have been shown for other bacterial species such as Salmonella and Caulobacter crescentus. Further analysis identified three c-di-GMP signaling proteins, i.e., PDE10355, DGC14945, and PDE14950, that play dominant roles in influencing the global c-di-GMP pool of strain EC1. The findings from this study highlight the complexity and plasticity of c-di-GMP regulatory circuits in different bacterial species. IMPORTANCE Dickeya zeae is the etiological agent of bacterial foot rot disease, which can cause massive economic losses in banana and rice plantations. Genome sequence analysis showed that D. zeae strain EC1 contains multiple c-di-GMP turnover genes, but their roles and regulatory mechanisms in bacterial physiology and virulence remain vague. By generating consecutive in-frame deletion mutants of the genes encoding c-di-GMP biosynthesis and degradation, respectively, we analyzed the individual and collective impacts of these c-di-GMP metabolic genes on the c-di-GMP global pool, bacterial physiology, and virulence. The significance of our study is in identifying the mechanism of c-di-GMP signaling in strain EC1 more clearly, which expands the c-di-GMP regulating patterns in Gram-negative species. The methods and experimental designs in this research will provide a valuable reference for the exploration of the complex c-di-GMP regulation mechanisms in other bacteria.

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confidence: 75%

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Systematic Analysis of c-di-GMP Signaling Mechanisms and Biological Functions in Dickeya zeae EC1

Chen

Zhou

et al. 2020

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“…A study has reported that polygalacturonase inhibiting proteins result in direct inhibition of PG activity or upregulate the defence pathways, in response to fungal infection (Nguema‐Onaet al, 2009). Deletion of either vfmI or vfmH of Dickeya zeae resulted in decreased production of CWDEs and alleviated virulence in host plants, according to Lv et al (2019); the report stated that the necrotizing effect depends on the enzymatic activity. In our study, in the early stage of infection, the pathogen secreted a large number of CWDEs to break through and dissolve the cell wall, and the amount of CWDEs that accumulated within Jz was sufficient to complete the subsequent infection at 4 days postinoculation.…”

Section: Discussionmentioning

confidence: 99%

Cell‐wall‐degrading enzymes produced by sesame leaf spot pathogen Corynespora cassiicola

Jiang

Liu

et al. 2020

Journal of Phytopathology

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Corynespora leaf spot (CLS) is one of the most important diseases in sesame and is caused by a fungal pathogen, Corynespora cassiicola. In this study, we investigated the role of cell‐wall‐degrading enzymes (CWDEs) in the process of pathogen infection and aimed to identify the enzyme that exerts positive effect. Corynespora cassiicola was inoculated in liquid culture and in sesame leaf. At 7 days postinoculation, CWDEs including polygalacturonase (PG), cellulase (CL), neutral xylanase (NEX) and laccase (LC) were detected in the supernatant and leaf extracts inoculated with Corynespora cassiicola. The result showed that the activities of LC and NEX were higher in liquid culture, while the activities of CL and PG were lower. In the sesame leaf infected by Corynespora cassiicola, the activity of NEX was the highest, those of CL and LC were the second highest and that of PG was the weakest, which indicated that NEX was the key enzyme in the process of sesame infection by Corynespora cassiicola. Secondly, the activities of the CWDEs secreted by Corynespora cassiicola were disparate in different sesame varieties. CWDEs activities of cultivar Jz were generally higher than cultivar Hn, and the activity change curve of Jz was also steeper than that of Hn. This indicates that the resistance mechanism of Hn may inhibit the activities of CWDEs and that the appearance and expansion of leaf necrosis spot is related to the comprehensive accumulation and action of various CWDEs. This is the first report investigating the association between CWDEs and pathogenesis of Corynespora cassiicola, causing Corynespora leaf spot in sesame.

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“…Among them, pGEX-6P-1, the bacterial vector for expressing GST fusion proteins with a PreScission protease site. The expression of this plasmid with the GST label enhances the solubility of the target protein and is widely used in the expression of the target protein, which has not been mentioned the ability of plasmid in killing the bacterial target in a large number of reported literature [ 24 , 47 , 48 , 49 , 50 ]. The screening of bacterial isolate QL-1 ( A. lactucae) capable of degrading DSF has been described previously [ 21 ].…”

Section: Methodsmentioning

confidence: 99%

“…An Xcc propagate in young stems and leaves through the vascular system, and disease appears as V-shaped chlorotic to necrotic lesions on leaf margins [24]. To determine the effect of the infection time on symptom development, the bacterial strains were inoculated into intact plants of Chinese cabbage and radish.…”

Section: Xcc Expressing Fady Loses Virulence In Plantamentioning

confidence: 99%

Whole-Genome Sequencing Analysis of Quorum Quenching Bacterial Strain Acinetobacter lactucae QL-1 Identifies the FadY Enzyme for Degradation of the Diffusible Signal Factor

Tian

Zhou

et al. 2020

IJMS

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The diffusible signal factor (DSF) is a fatty acid signal molecule and is widely conserved in various Gram-negative bacteria. DSF is involved in the regulation of pathogenic virulence in many bacterial pathogens, including Xanthomonas campestris pv. campestris (Xcc). Quorum quenching (QQ) is a potential approach for preventing and controlling DSF-mediated bacterial infections by the degradation of the DSF signal. Acinetobacter lactucae strain QL-1 possesses a superb DSF degradation ability and effectively attenuates Xcc virulence through QQ. However, the QQ mechanisms in strain QL-1 are still unknown. In the present study, whole-genome sequencing and comparative genomics analysis were conducted to identify the molecular mechanisms of QQ in strain QL-1. We found that the fadY gene of QL-1 is an ortholog of XccrpfB, a known DSF degradation gene, suggesting that strain QL-1 is capable of inactivating DSF by QQ enzymes. The results of site-directed mutagenesis indicated that fadY is required for strain QL-1 to degrade DSF. The determination of FadY activity in vitro revealed that the fatty acyl-CoA synthetase FadY had remarkable catalytic activity. Furthermore, the expression of fadY in transformed Xcc strain XC1 was investigated and shown to significantly attenuate bacterial pathogenicity on host plants, such as Chinese cabbage and radish. This is the first report demonstrating a DSF degradation enzyme from A. lactucae. Taken together, these findings shed light on the QQ mechanisms of A. lactucae strain QL-1, and provide useful enzymes and related genes for the biocontrol of infectious diseases caused by DSF-dependent bacterial pathogens.

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A two‐component regulatory system VfmIH modulates multiple virulence traits in Dickeya zeae

Cited by 33 publications

References 51 publications

Systematic Analysis of c-di-GMP Signaling Mechanisms and Biological Functions in Dickeya zeae EC1

Systematic Analysis of c-di-GMP Signaling Mechanisms and Biological Functions in Dickeya zeae EC1

Cell‐wall‐degrading enzymes produced by sesame leaf spot pathogen Corynespora cassiicola

Whole-Genome Sequencing Analysis of Quorum Quenching Bacterial Strain Acinetobacter lactucae QL-1 Identifies the FadY Enzyme for Degradation of the Diffusible Signal Factor

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