Bacterial Two-Component Systems: Structures and Signaling Mechanisms

Wang, Shuishu

doi:10.5772/48277

Cited by 35 publications

(45 citation statements)

References 61 publications

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“…RsrS has a predicted unique sensor domain, suggesting that it has the ability to detect the signal from tetrathionate. These results are consistent with the previously reported mechanism of TCS in translating environmental stimuli to specific adaptive responses (Martínez-Hackert and Stock, 1997; Mattison and Kenney, 2002; Wang, 2012). Therefore, we propose a tetrathionate-dependent transcriptional regulation model of the S 4 I pathway by RsrS-RsrR in A. caldus .…”

Section: Discussionsupporting

confidence: 93%

The Two-Component System RsrS-RsrR Regulates the Tetrathionate Intermediate Pathway for Thiosulfate Oxidation in Acidithiobacillus caldus

Wang

Lin

et al. 2016

Front. Microbiol.

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Acidithiobacillus caldus (A. caldus) is a common bioleaching bacterium that possesses a sophisticated and highly efficient inorganic sulfur compound metabolism network. Thiosulfate, a central intermediate in the sulfur metabolism network of A. caldus and other sulfur-oxidizing microorganisms, can be metabolized via the tetrathionate intermediate (S4I) pathway catalyzed by thiosulfate:quinol oxidoreductase (Tqo or DoxDA) and tetrathionate hydrolase (TetH). In A. caldus, there is an additional two-component system called RsrS-RsrR. Since rsrS and rsrR are arranged as an operon with doxDA and tetH in the genome, we suggest that the regulation of the S4I pathway may occur via the RsrS-RsrR system. To examine the regulatory role of the two-component system RsrS-RsrR on the S4I pathway, ΔrsrR and ΔrsrS strains were constructed in A. caldus using a newly developed markerless gene knockout method. Transcriptional analysis of the tetH cluster in the wild type and mutant strains revealed positive regulation of the S4I pathway by the RsrS-RsrR system. A 19 bp inverted repeat sequence (IRS, AACACCTGTTACACCTGTT) located upstream of the tetH promoter was identified as the binding site for RsrR by using electrophoretic mobility shift assays (EMSAs) in vitro and promoter-probe vectors in vivo. In addition, ΔrsrR, and ΔrsrS strains cultivated in K2S4O6-medium exhibited significant growth differences when compared with the wild type. Transcriptional analysis indicated that the absence of rsrS or rsrR had different effects on the expression of genes involved in sulfur metabolism and signaling systems. Finally, a model of tetrathionate sensing by RsrS, signal transduction via RsrR, and transcriptional activation of tetH-doxDA was proposed to provide insights toward the understanding of sulfur metabolism in A. caldus. This study also provided a powerful genetic tool for studies in A. caldus.

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Section: Discussionsupporting

confidence: 93%

The Two-Component System RsrS-RsrR Regulates the Tetrathionate Intermediate Pathway for Thiosulfate Oxidation in Acidithiobacillus caldus

Wang

Lin

et al. 2016

Front. Microbiol.

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“…All protein-protein interactions studied were examined in three media (complex LB medium, minimal medium with 2 mM M P i , and minimal medium with 40 M P i ), and any interactions that were detected were observed in all three media. Relative to the positive Zip-Zip control and negative PhoU-Zip and PhoR-Zip controls, we failed to detect a PhoU-PstB, PhoU-PhoB, or PstB-PhoR interaction but did observe a PhoR-PhoR interaction (Table 2) as expected for a histidine kinase (41). The S. meliloti PhoU protein was observed to interact with itself and with PhoR (Table 2) as was previously reported for the E. coli PhoU protein (19).…”

Section: Resultsmentioning

confidence: 48%

PhoU Allows Rapid Adaptation to High Phosphate Concentrations by Modulating PstSCAB Transport Rate in Sinorhizobium meliloti

et al. 2017

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Maintenance of cellular phosphate homeostasis is essential for cellular life. The PhoU protein has emerged as a key regulator of this process in bacteria, and it is suggested to modulate phosphate import by PstSCAB and control activation of the phosphate limitation response by the PhoR-PhoB two-component system. However, a proper understanding of PhoU has remained elusive due to numerous complications of mutating phoU, including loss of viability and the genetic instability of the mutants. Here, we developed two sets of strains of Sinorhizobium meliloti that overcame these limitations and allowed a more detailed and comprehensive analysis of the biological and molecular activities of PhoU. The data showed that phoU cannot be deleted in the presence of phosphate unless PstSCAB is inactivated also. However, phoU deletions were readily recovered in phosphatefree media, and characterization of these mutants revealed that addition of phosphate to the environment resulted in toxic levels of PstSCAB-mediated phosphate accumulation. Phosphate uptake experiments indicated that PhoU significantly decreased the PstSCAB transport rate specifically in phosphate-replete cells but not in phosphate-starved cells and that PhoU could rapidly respond to elevated environmental phosphate concentrations and decrease the PstSCAB transport rate. Sitedirected mutagenesis results suggested that the ability of PhoU to respond to phosphate levels was independent of the conformation of the PstSCAB transporter. Additionally, PhoU-PhoU and PhoU-PhoR interactions were detected using a bacterial two-hybrid screen. We propose that PhoU modulates PstSCAB and PhoR-PhoB in response to local, internal fluctuations in phosphate concentrations resulting from PstSCAB-mediated phosphate import.IMPORTANCE Correct maintenance of cellular phosphate homeostasis is critical in all kingdoms of life and in bacteria involves the PhoU protein. This work provides novel insights into the role of the Sinorhizobium meliloti PhoU protein, which plays a key role in rapid adaptation to elevated phosphate concentrations. It is shown that PhoU rapidly responds to elevated phosphate levels by significantly decreasing the phosphate transport of PstSCAB, thereby preventing phosphate toxicity and cell death. Additionally, a new model for phosphate sensing in bacterial species which involves the PhoR-PhoB two-component system is presented. This work provides new insights into the bacterial response to changing environmental conditions and into regulation of the phosphate limitation response that influences numerous bacterial processes, including antibiotic production and virulence.KEYWORDS Pho regulon, PhoU, PstSCAB, Sinorhizobium meliloti, environmental adaptation, modulation of TCS, phosphate homeostasis, phosphate sensing, phosphate transport, transport modulation

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“…Hence, we looked for the activation of potential signaling mechanisms involving autoinducers or secondary messengers which might trigger this specific interaction. In the presence of TBZ we observed up-regulation of several luxRI -like two-component sensory-histidine-kinase/regulatory genes, annotated as fixLJ [95, 96] at the Sphingomonas MAG 3X21F, which did not appear to correlate with other members of the consortium. The fixLJ two component system is considered to sense oxygen in nitrogen fixing bacteria, yet, a broader sensory role of this two-component system was postulated in other bacteria (i.e.…”

Section: Discussionmentioning

confidence: 92%

Nutritional inter-dependencies and a carbazole-dioxygenase are key elements of a bacterial consortium relying on aSphingomonasfor the degradation of the fungicide thiabendazole

Vasileiadis

Perruchon

Scheer

et al. 2020

Preprint

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22Background: Thiabendazole (TBZ), is a benzimidazole fungicide and anthelminthic whose high 23 persistence and toxicity pose a serious environmental threat. In our quest for environmental mitigation 24 we previously isolated the first TBZ-degrading bacterial consortium and provided preliminary evidence 25 for its composition and the degrading role of a Sphingomonas. Here, we employed a multi-omic 26 approach combined with DNA-stable isotope probing (SIP) to determine the genetic make-up of the 27 key consortium members, to disentangle nutritional and metabolic interdependencies, to identify the 28 transformation pathway of TBZ and to understand the genetic network driving its transformation. 29Results: Time-series SIP in combination with amplicon sequencing analysis verified the key role of 30 Sphingomonas in TBZ degradation by assimilating over 80% of the 13 C-labelled phenyl moiety of TBZ. 31Non-target mass spectroscopy (MS) analysis showed the accumulation of thiazole-4-carboxamidine as 32 a single dead-end transformation product and no phenyl-containing derivative, in line with the phenyl 33 moiety assimilation in the SIP analysis. Time series metagenomic analysis of the consortium 34 supplemented with TBZ or succinate led to the assembly of 18 metagenome-assembled genomes 35 (MAGs) with >80% completeness, six (Sphingomonas 3X21F, γ-Proteobacterium 34A, 36Bradyrhizobiaceae 9B and Hydrogenophaga 19A, 13A, and 23F) being dominant. Meta-transcriptomic 37 and -proteomic analysis suggested that Sphingomonas mobilize a carbazole dioxygenase (car) operon 38 during the initial cleavage of TBZ to thiazole-4-carboxamidine and catechol, the latter is further 39 transformed by enzymes encoded in a catechol ortho-cleavage (cat) operon; both operons being up-40 regulated during TBZ degradation. Computational docking analysis of the terminal oxygenase 41 component of car, CarAa, showed high affinity to TBZ, comparable to carbazole, reinforcing its high 42 potency for TBZ transformation. These results suggest no interactions between consortium members in 43 TBZ transformation, performed solely by Sphingomonas. In contrast, gene expression network analysis 44 revealed strong interactions between Sphingomonas MAG 3X12F and Hydrogenophaga MAG 23F, 45with Hydrogenophaga activating its cobalamin biosynthetic pathway and Sphingomonas its cobalamin 46 salvage pathway along TBZ degradation. 47 Conclusions:Our findings suggest interactions between consortium members which align with the 48 "black queen hypothesis": Sphingomonas detoxifies TBZ, releasing consortium members by a toxicant; 49 in return for this, Hydrogenophaga 23F provides cobalamin to the auxotrophic Sphingomonas. 50 Background 54 Thiabendazole (TBZ) is a benzimidazole compound which is used as a post-harvest fungicide to control 55 fungal infestations on fruits during storage [1] and as a broad spectrum anthelminthic to control 56 endoparasites in livestock farming [2]. It acts by binding to tubulin monomers inhibiting the 57 polymerization of microtubules and, thus,...

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Bacterial Two-Component Systems: Structures and Signaling Mechanisms

Cited by 35 publications

References 61 publications

The Two-Component System RsrS-RsrR Regulates the Tetrathionate Intermediate Pathway for Thiosulfate Oxidation in Acidithiobacillus caldus

The Two-Component System RsrS-RsrR Regulates the Tetrathionate Intermediate Pathway for Thiosulfate Oxidation in Acidithiobacillus caldus

PhoU Allows Rapid Adaptation to High Phosphate Concentrations by Modulating PstSCAB Transport Rate in Sinorhizobium meliloti

Nutritional inter-dependencies and a carbazole-dioxygenase are key elements of a bacterial consortium relying on aSphingomonasfor the degradation of the fungicide thiabendazole

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