scholarly journals The GGDEF-domain protein GdpX1 attenuates motility, exopolysaccharide production and virulence in Xanthomonas oryzae pv. oryzae

2016 ◽  
Vol 120 (6) ◽  
pp. 1646-1657 ◽  
Author(s):  
F. Yang ◽  
S. Qian ◽  
F. Tian ◽  
H. Chen ◽  
W. Hutchins ◽  
...  
2021 ◽  
Vol 9 (3) ◽  
pp. 495
Author(s):  
Weiwei Yan ◽  
Yiming Wei ◽  
Susu Fan ◽  
Chao Yu ◽  
Fang Tian ◽  
...  

Cyclic diguanylate monophosphate (c-di-GMP) is a secondary messenger present in bacteria. The GGDEF-domain proteins can participate in the synthesis of c-di-GMP as diguanylate cyclase (DGC) or bind with c-di-GMP to function as a c-di-GMP receptor. In the genome of Xanthomonas oryzae pv. oryzae (Xoo), the causal agent of bacterial blight of rice, there are 11 genes that encode single GGDEF domain proteins. The GGDEF domain protein, PXO_02019 (here GdpX6 [GGDEF-domain protein of Xoo6]) was characterized in the present study. Firstly, the DGC and c-di-GMP binding activity of GdpX6 was confirmed in vitro. Mutation of the crucial residues D403 residue of the I site in GGDEF motif and E411 residue of A site in GGDEF motif of GdpX6 abolished c-di-GMP binding activity and DGC activity of GdpX6, respectively. Additionally, deletion of gdpX6 significantly increased the virulence, swimming motility, and decreased sliding motility and biofilm formation. In contrast, overexpression of GdpX6 in wild-type PXO99A strain decreased the virulence and swimming motility, and increased sliding motility and biofilm formation. Mutation of the E411 residue but not D403 residue of the GGDEF domain in GdpX6 abolished its biological functions, indicating the DGC activity to be imperative for its biological functions. Furthermore, GdpX6 exhibited multiple subcellular localization in bacterial cells, and D403 or E411 did not contribute to the localization of GdpX6. Thus, we concluded that GdpX6 exhibits DGC activity to control the virulence, swimming and sliding motility, and biofilm formation in Xoo.


2014 ◽  
Vol 27 (6) ◽  
pp. 578-589 ◽  
Author(s):  
Fenghuan Yang ◽  
Fang Tian ◽  
Xiaotong Li ◽  
Susu Fan ◽  
Huamin Chen ◽  
...  

Degenerate GGDEF and EAL domain proteins represent major types of cyclic diguanylic acid (c-di-GMP) receptors in pathogenic bacteria. Here, we characterized a FimX-like protein (Filp) which possesses both GGDEF and EAL domains in Xanthomonas oryzae pv. oryzae, the causal agent of bacterial blight of rice. Both in silico analysis and enzyme assays indicated that the GGDEF and EAL domains of Filp were degenerate and enzymatically inactive. However, Filp bound to c-di-GMP efficiently within the EAL domain, where Q477, E653, and F654 residues were crucial for the binding. Deletion of the filp gene in X. oryzae pv. oryzae resulted in attenuated virulence in rice and reduced type III secretion system (T3SS) gene expression. Complementation analysis with different truncated proteins indicated that REC, PAS, and EAL domains but not the GGDEF domain were required for the full activity of Filp in vivo. In addition, a PilZ-domain protein (PXO_02715) was identified as a Filp interactor by yeast two-hybrid and glutathione-S-transferase pull-down assays. Deletion of the PXO_02715 gene demonstrated changes in bacterial virulence and T3SS gene expression similar to Δfilp. Moreover, both mutants were impaired in their ability to induce hypersensitive response in nonhost plants. Thus, we concluded that Filp was a novel c-di-GMP receptor of X. oryzae pv. oryzae, and its function to regulate bacterial virulence expression might be via the interaction with PXO_02715.


2015 ◽  
Vol 83 (8) ◽  
pp. 3302-3310 ◽  
Author(s):  
Chuan Chen ◽  
Xu Zhang ◽  
Fei Shang ◽  
Haipeng Sun ◽  
Baolin Sun ◽  
...  

Staphylococcus aureusis an important Gram-positive pathogen responsible for numerous diseases ranging from localized skin infections to life-threatening systemic infections. The virulence ofS. aureusis essentially determined by a wide spectrum of factors, including cell wall-associated proteins and secreted toxins that are precisely controlled in response to environmental changes. GGDEF domain protein fromStaphylococcus(GdpS) is the only conserved staphylococcal GGDEF domain protein that is involved not in c-di-GMP synthesis but in the virulence regulation ofS. aureusNCTC8325. Our previous study showed that the inactivation ofgdpSgenerates an extensive change of virulence factors together with, in particular, a major Spa (protein A) surface protein. As reported,sarSis a direct positive regulator ofspa. The decreased transcript levels ofsarSin thegdpSmutant compared with the parental NCTC8325 strain suggest thatgdpSaffectsspathrough interaction withsarS. In this study, site mutation and complementary experiments showed that the translation product ofgdpSwas not involved in the regulation of transcript levels ofsarS. We found thatgdpSfunctioned through direct RNA-RNA base pairing with the 5′ untranslated region (5′UTR) ofsarSmRNA and that a putative 18-nucleotide region played a significant role in the regulatory process. Furthermore, the mRNA half-life analysis ofsarSin thegdpSmutant showed thatgdpSpositively regulates the mRNA levels ofsarSby contributing to the stabilization ofsarSmRNA, suggesting thatgdpSmRNA may regulatespaexpression in an RNA-dependent pathway.


2018 ◽  
Vol 19 (10) ◽  
pp. 3038 ◽  
Author(s):  
Nahee Bae ◽  
Hye-Jee Park ◽  
Hanbi Park ◽  
Minyoung Kim ◽  
Eunsoo Do ◽  
...  

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.


2020 ◽  
Vol 33 (10) ◽  
pp. 1196-1208
Author(s):  
Muhammad Umar Shahbaz ◽  
Shanshan Qian ◽  
Fei Yun ◽  
Jie Zhang ◽  
Chao Yu ◽  
...  

The degenerate GGDEF/EAL domain protein Filp was previously shown to function as a cyclic di-GMP (c-di-GMP) signal receptor through its specific interaction with an atypical PilZ domain protein PilZX3 (formerly PXO_02715) and that this interaction is involved in regulating virulence in Xanthomonas oryzae pv. oryzae. As a step toward understanding the regulatory role of Filp/PilZX3-mediated c-di-GMP signaling in the virulence of X. oryzae pv. oryzae, differentially expressed proteins (DEPs) downstream of Filp/PilZX3 were identified by isobaric tagging for relative and absolute quantitation (iTRAQ). A total of 2,346 proteins were identified, of which 157 displayed significant differential expression in different strains. Western blot and quantitative reverse transcription-PCR analyses showed that the expression of HrrP (histidine kinase-response regulator hybrid protein), PhrP (PhoPQ-regulated protein), ProP (prophage Lp2 protein 6) were increased in the ∆filp, ∆pilZX3, and ∆filp∆pilZX3 mutant strains, while expression of CheW1 (chemotaxis protein CheW1), EdpX2 (the second EAL domain protein identified in X. oryzae pv. oryzae), HGdpX2 (the second HD-GYP domain protein identified in X. oryzae pv. oryzae) was decreased in all mutant strains compared with that in the wild type, which was consistent with the iTRAQ data. Deletion of the hrrP and proP genes resulted in significant increases in virulence, whereas deletion of the cheW1, hGdpX2, or tdrX2 genes resulted in decreased virulence. Enzyme assays indicated that EdpX2 and HGdpX2 were active phosphodiesterases (PDEs). This study provides a proteomic description of putative regulatory pathway of Filp and PilZX3 and characterized novel factors that contributed to the virulence of X. oryzae pv. oryzae regulated by c-di-GMP signaling.


2011 ◽  
Vol 77 (6) ◽  
pp. 2196-2198 ◽  
Author(s):  
Shauna Rakshe ◽  
Maija Leff ◽  
Alfred M. Spormann

ABSTRACTThe GGDEF domain protein MxdA, which is important for biofilm formation inShewanella oneidensisMR-1, was hypothesized to possess diguanylate cyclase activity. Here, we demonstrate that while MxdA controls the cellular level of c-di-GMP inS. oneidensis, it modulates the c-di-GMP pool indirectly.


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