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Gentry-Lear Z, Franco K, Shavlik M, Harms MJ, Baylink A. Navigating contradictions: Salmonella Typhimurium chemotactic responses to conflicting chemoeffector signals show parity with bacterial growth benefits. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.18.576330. [PMID: 38293242 PMCID: PMC10827161 DOI: 10.1101/2024.01.18.576330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
Many bacteria that colonize the guts of animals use chemotaxis to direct swimming motility and select sites for colonization based on sources of effectors derived from the host, diet, and microbial competitors of the local environ. The complex ecosystem of the gastrointestinal tract contains mixtures of chemoattractants and chemorepellents, but it remains poorly understood how swimming bacteria navigate conflicting signals. The enteric pathogen Salmonella Typhimurium possesses Tsr, a chemoreceptor protein that directs both chemoattraction and chemorepulsion responses, which we employed as a model to study chemotaxis in the presence of conflicting effector stimuli. We investigated how S. Typhimurium responds to human fecal matter, an effector source in the enteric lumen that contains high concentrations of indole, a bacteriostatic chemorepellent produced by the native commensals of the microbiota, and also nutrients such as l-serine, a chemoattractant. The indole concentration in human feces is more than 12-fold the concentration required for half-maximal chemorepulsion, however, we find S. Typhimurium, and various clinical isolates of non-typhoidal S. enterica serovars, are strongly attracted to liquid fecal matter. We further investigated the chemotactic responses of S. Typhimurium to titrations of indole and l-serine and revealed that chemorepulsion to indole is overridden in the presence of excess l-serine. We capture the inversion of these two opposing taxis behaviors in a phenomenon we define as "chemohalation" in which the bacteria organize into a halo around the treatment source with an interior zone of avoidance, which represents a compromise between chemoattraction and chemorepulsion. Growth analyses reveal that the chemotactic responses to these opposing effectors align chemoattraction and chemorepulsion with the relative growth of the bacteria in culture. Hence, our study supports the view that evolution has finely tuned chemotaxis to assess environmental habitability by evaluating the tradeoffs in bacterial growth based on the local combination of effectors.
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Affiliation(s)
- Zealon Gentry-Lear
- University of Oregon, Department of Chemistry & Biochemistry, Eugene, OR, 97403
| | - Kailie Franco
- Washington State University, Department of Veterinary Microbiology and Pathology, Pullman, WA 99164
| | - Michael Shavlik
- University of Oregon, Department of Chemistry & Biochemistry, Eugene, OR, 97403
| | - Michael J. Harms
- University of Oregon, Department of Chemistry & Biochemistry, Eugene, OR, 97403
- University of Oregon, Institute of Molecular Biology, Eugene, OR, 97403
| | - Arden Baylink
- Washington State University, Department of Veterinary Microbiology and Pathology, Pullman, WA 99164
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Arboleda-García A, Alarcon-Ruiz I, Boada-Acosta L, Boada Y, Vignoni A, Jantus-Lewintre E. Advancements in synthetic biology-based bacterial cancer therapy: A modular design approach. Crit Rev Oncol Hematol 2023; 190:104088. [PMID: 37541537 DOI: 10.1016/j.critrevonc.2023.104088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2023] [Revised: 07/18/2023] [Accepted: 07/31/2023] [Indexed: 08/06/2023] Open
Abstract
Synthetic biology aims to program living bacteria cells with artificial genetic circuits for user-defined functions, transforming them into powerful tools with numerous applications in various fields, including oncology. Cancer treatments have serious side effects on patients due to the systemic action of the drugs involved. To address this, new systems that provide localized antitumoral action while minimizing damage to healthy tissues are required. Bacteria, often considered pathogenic agents, have been used as cancer treatments since the early 20th century. Advances in genetic engineering, synthetic biology, microbiology, and oncology have improved bacterial therapies, making them safer and more effective. Here we propose six modules for a successful synthetic biology-based bacterial cancer therapy, the modules include Payload, Release, Tumor-targeting, Biocontainment, Memory, and Genetic Circuit Stability Module. These will ensure antitumor activity, safety for the environment and patient, prevent bacterial colonization, maintain cell stability, and prevent loss or defunctionalization of the genetic circuit.
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Affiliation(s)
- Andrés Arboleda-García
- Systems Biology and Biosystems Control Lab, Instituto de Automática e Informática Industrial, Universitat Politècnica de València, Spain
| | - Ivan Alarcon-Ruiz
- Gene Regulation in Cardiovascular Remodeling and Inflammation Group, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain; Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain; Departamento de Biología Molecular, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid, Spain
| | - Lissette Boada-Acosta
- Centro de Investigación Biomédica en Red Cáncer, CIBERONC, Madrid, Spain; TRIAL Mixed Unit, Centro de Investigación Príncipe Felipe-Fundación Investigación del Hospital General Universitario de Valencia, Valencia, Spain; Molecular Oncology Laboratory, Fundación Investigación del Hospital General Universitario de Valencia, Valencia, Spain
| | - Yadira Boada
- Systems Biology and Biosystems Control Lab, Instituto de Automática e Informática Industrial, Universitat Politècnica de València, Spain
| | - Alejandro Vignoni
- Systems Biology and Biosystems Control Lab, Instituto de Automática e Informática Industrial, Universitat Politècnica de València, Spain.
| | - Eloisa Jantus-Lewintre
- Centro de Investigación Biomédica en Red Cáncer, CIBERONC, Madrid, Spain; TRIAL Mixed Unit, Centro de Investigación Príncipe Felipe-Fundación Investigación del Hospital General Universitario de Valencia, Valencia, Spain; Molecular Oncology Laboratory, Fundación Investigación del Hospital General Universitario de Valencia, Valencia, Spain; Department of Biotechnology, Universitat Politècnica de València, Valencia, Spain
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Liu X, Liu Q, Sun S, Sun H, Wang Y, Shen X, Zhang L. Exploring AI-2-mediated interspecies communications within rumen microbial communities. MICROBIOME 2022; 10:167. [PMID: 36203182 PMCID: PMC9540692 DOI: 10.1186/s40168-022-01367-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/06/2022] [Accepted: 09/02/2022] [Indexed: 06/16/2023]
Abstract
BACKGROUND The rumen is an ecosystem with a complex microbial microflora in which microbes initiate biofilm formation by attaching to plant surfaces for plant degradation and are capable of converting feed to nutrients and energy via microbial processes. Quorum sensing (QS) is a cell-to-cell communication mechanism that allows microbes to synchronize the expression of multiple genes in the group to perform social behaviors such as chemotaxis and biofilm formation using self-synthesized QS signaling molecules. Whereas QS has been extensively studied in model microorganisms under pure culture conditions, QS mechanisms are poorly understood in complex bacterial communities, such as the rumen microflora, in which cell-to-cell communication may be common. RESULTS Here, we analyzed 981 rumens bacterial and archaeal genomes from the Joint Genome Institute (JGI) and GenBank databases and identified 15 types of known QS signaling molecule-related genes. The analysis of the prevalence and abundance of genes involved in QS showed that 767 microbial genomes appeared to possess QS-related genes, including 680 bacterial genomes containing autoinducer-2 (AI-2) synthase- or receptor-encoding genes. Prevotella, Butyivibrio, Ruminococcus, Oribacterium, Selenomonas, and Treponema, known abundant bacterial genera in the rumen, possessed the greatest numbers of AI-2-related genes; these genes were highly expressed within the metatranscriptome dataset, suggesting that intra- and interspecies communication mediated by AI-2 among rumen microbes was universal in the rumen. The QS processes mediated by the dCache_1-containing AI-2 receptors (CahRs) with various functional modules may be essential for degrading plants, digesting food, and providing energy and nutrients to the host. Additionally, a universal natural network based on QS revealed how rumen microbes coordinate social behaviors via the AI-2-mediated QS system, most of which may potentially function via AI-2 binding to the extracellular sensor dCache_1 domain to activate corresponding receptors involved in different signal transduction pathways, such as methyl-accepting chemotaxis proteins, histidine kinases, serine phosphatases, c-di-GMP synthases and phosphodiesterases, and serine/threonine kinases in the rumen. CONCLUSIONS The exploration of AI-2-related genes, especially CahR-type AI-2 receptors, greatly increased our insight into AI-2 as a potentially "universal" signal mediating social behaviors and will help us better understand microbial communication networks and the function of QS in plant-microbe interactions in complex microecosystems. Video Abstract.
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Affiliation(s)
- Xiaozhen Liu
- Department of Microbiology and Bioengineering, College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Qinmeng Liu
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Sihuai Sun
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Hengxi Sun
- Department of Microbiology and Bioengineering, College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Yao Wang
- Department of Biotechnology, College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Xihui Shen
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, China.
| | - Lei Zhang
- Department of Microbiology and Bioengineering, College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, China.
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Tumewu SA, Watanabe Y, Matsui H, Yamamoto M, Noutoshi Y, Toyoda K, Ichinose Y. Identification of Aerotaxis Receptor Proteins Involved in Host Plant Infection by Pseudomonas syringae pv. tabaci 6605. Microbes Environ 2022; 37:ME21076. [PMID: 35264479 PMCID: PMC8958299 DOI: 10.1264/jsme2.me21076] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Accepted: 01/11/2022] [Indexed: 11/12/2022] Open
Abstract
Pseudomonas syringae pv. tabaci 6605 (Pta6605) is a foliar plant pathogen that causes wildfire disease on tobacco plants. It requires chemotaxis to enter plants and establish infection. While chemotactic signals appear to be the main mechanism by which Pta6605 performs directional movement, the involvement of aerotaxis or energy taxis by this foliar pathogen is currently unknown. Based on domain structures and similarity with more than 50 previously identified putative methyl-accepting chemotaxis proteins (MCPs), the genome of Pta6605 encodes three potential aerotaxis transducers. We identified AerA as the main aerotaxis transducer and found that it possesses a taxis-to-serine-and-repellent (Tsr)-like domain structure that supports a periplasmic 4HB-type ligand-binding domain (LBD). The secondary aerotaxis transducer, AerB, possesses a cytosolic PAS-type LBD, similar to the Aer of Escherichia coli and Pseudomonas aeruginosa. Aerotaxis ability by single and double mutant strains of aerA and aerB was weaker than that by wild-type Pta6605. On the other hand, another cytosolic PAS-type LBD containing MCP did not make a major contribution to Pta6605 aerotaxis in our assay system. Furthermore, mutations in aerotaxis transducer genes did not affect surface motility or chemotactic attraction to yeast extract. Single and double mutant strains of aerA and aerB showed less colonization in the early stage of host plant infection and lower biofilm production than wild-type Pta6605. These results demonstrate the presence of aerotaxis transducers and their contribution to host plant infection by Pta6605.
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Affiliation(s)
- Stephany Angelia Tumewu
- Graduate School of Environmental and Life Science, Okayama University, Tsushima-naka 1–1–1, Kita-ku, Okayama 700–8530, Japan
- The United Graduate School of Agricultural Science, Gifu University, 1–1 Yanagido, Gifu, Gifu 501–1193, Japan
| | - Yuta Watanabe
- Faculty of Agriculture, Okayama University, Tsushima-naka 1–1–1, Kita-ku, Okayama 700–8530, Japan
| | - Hidenori Matsui
- Graduate School of Environmental and Life Science, Okayama University, Tsushima-naka 1–1–1, Kita-ku, Okayama 700–8530, Japan
- Faculty of Agriculture, Okayama University, Tsushima-naka 1–1–1, Kita-ku, Okayama 700–8530, Japan
| | - Mikihiro Yamamoto
- Graduate School of Environmental and Life Science, Okayama University, Tsushima-naka 1–1–1, Kita-ku, Okayama 700–8530, Japan
- Faculty of Agriculture, Okayama University, Tsushima-naka 1–1–1, Kita-ku, Okayama 700–8530, Japan
| | - Yoshiteru Noutoshi
- Graduate School of Environmental and Life Science, Okayama University, Tsushima-naka 1–1–1, Kita-ku, Okayama 700–8530, Japan
- Faculty of Agriculture, Okayama University, Tsushima-naka 1–1–1, Kita-ku, Okayama 700–8530, Japan
| | - Kazuhiro Toyoda
- Graduate School of Environmental and Life Science, Okayama University, Tsushima-naka 1–1–1, Kita-ku, Okayama 700–8530, Japan
- Faculty of Agriculture, Okayama University, Tsushima-naka 1–1–1, Kita-ku, Okayama 700–8530, Japan
| | - Yuki Ichinose
- Graduate School of Environmental and Life Science, Okayama University, Tsushima-naka 1–1–1, Kita-ku, Okayama 700–8530, Japan
- Faculty of Agriculture, Okayama University, Tsushima-naka 1–1–1, Kita-ku, Okayama 700–8530, Japan
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Tumewu SA, Matsui H, Yamamoto M, Noutoshi Y, Toyoda K, Ichinose Y. Identification of chemoreceptor proteins for amino acids involved in host plant infection in Pseudomonas syringae pv. tabaci 6605. Microbiol Res 2021; 253:126869. [PMID: 34597823 DOI: 10.1016/j.micres.2021.126869] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 08/02/2021] [Accepted: 09/20/2021] [Indexed: 11/23/2022]
Abstract
Chemotaxis is crucial for Pseudomonas syringae pv. tabaci (Pta) 6605 to evoke disease in tobacco plants. Pta6605 harbors more than fifty genes for methyl-accepting chemotaxis proteins (mcp), but almost all are functionally uncharacterized. Previously we identified a dCache_1 type MCP in Pta6605 that mediates chemotaxis to γ-aminobutyric acid, called McpG. In this study, we characterized four more dCache_1 type MCPs, three of which, PscA, PscB, and PscC2, are responsible for sensing amino acids. Using a capillary chemotaxis assay, we observed that PscA, PscB, and PscC2 mutant strains had reduced chemotaxis to most amino acids, indicating that PscA and PscB mediate chemotaxis to 14 amino acids, while PscC2 has a slightly narrower ligand recognition, mediating chemotaxis to 12 amino acids. Other cellular functions were also affected in ΔpscB and ΔpscC2: swarming motility was reduced, and biofilm formation was increased. Furthermore, ΔpscB and ΔpscC2 but not ΔpscA had reduced virulence in the host tobacco plant. On the other hand, ΔpscC1 was defective in motility and did not even respond to yeast extract and was unable to cause disease. These findings supported the idea that the chemosensory pathway correlated with virulence-related phenotypes. Amino acids are abundant in tobacco apoplast; having multiple MCPs appears to support the invasion of Pta6605 into the plant.
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Affiliation(s)
- Stephany Angelia Tumewu
- Graduate School of Environmental and Life Science, Okayama University, Tsushima-naka 1-1-1, Kita-ku, Okayama 700-8530, Japan
| | - Hidenori Matsui
- Graduate School of Environmental and Life Science, Okayama University, Tsushima-naka 1-1-1, Kita-ku, Okayama 700-8530, Japan
| | - Mikihiro Yamamoto
- Graduate School of Environmental and Life Science, Okayama University, Tsushima-naka 1-1-1, Kita-ku, Okayama 700-8530, Japan
| | - Yoshiteru Noutoshi
- Graduate School of Environmental and Life Science, Okayama University, Tsushima-naka 1-1-1, Kita-ku, Okayama 700-8530, Japan
| | - Kazuhiro Toyoda
- Graduate School of Environmental and Life Science, Okayama University, Tsushima-naka 1-1-1, Kita-ku, Okayama 700-8530, Japan
| | - Yuki Ichinose
- Graduate School of Environmental and Life Science, Okayama University, Tsushima-naka 1-1-1, Kita-ku, Okayama 700-8530, Japan.
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The Only Chemoreceptor Encoded by che Operon Affects the Chemotactic Response of Agrobacterium to Various Chemoeffectors. Microorganisms 2021; 9:microorganisms9091923. [PMID: 34576817 PMCID: PMC8466855 DOI: 10.3390/microorganisms9091923] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 09/02/2021] [Accepted: 09/07/2021] [Indexed: 12/16/2022] Open
Abstract
Chemoreceptor (also called methyl-accepting chemotaxis protein, MCP) is the leading signal protein in the chemotaxis signaling pathway. MCP senses and binds chemoeffectors, specifically, and transmits the sensed signal to downstream proteins of the chemotaxis signaling system. The genome of Agrobacterium fabrum (previously, tumefaciens) C58 predicts that a total of 20 genes can encode MCP, but only the MCP-encoding gene atu0514 is located inside the che operon. Hence, the identification of the exact function of atu0514-encoding chemoreceptor (here, named as MCP514) will be very important for us to understand more deeply the chemotaxis signal transduction mechanism of A. fabrum. The deletion of atu0514 significantly decreased the chemotactic migration of A. fabrum in a swim plate. The test of atu0514-deletion mutant (Δ514) chemotaxis toward single chemicals showed that the deficiency of MCP514 significantly weakened the chemotactic response of A. fabrum to four various chemicals, sucrose, valine, citric acid and acetosyringone (AS), but did not completely abolish the chemotactic response. MCP514 was localized at cell poles although it lacks a transmembrane (TM) region and is predicted to be a cytoplasmic chemoreceptor. The replacement of residue Phe328 showed that the helical structure in the hairpin subdomain of MCP514 is a direct determinant for the cellular localization of MCP514. Single respective replacements of key residues indicated that residues Asn336 and Val353 play a key role in maintaining the chemotactic function of MCP514.
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Matilla MA, Velando F, Martín-Mora D, Monteagudo-Cascales E, Krell T. A catalogue of signal molecules that interact with sensor kinases, chemoreceptors and transcriptional regulators. FEMS Microbiol Rev 2021; 46:6356564. [PMID: 34424339 DOI: 10.1093/femsre/fuab043] [Citation(s) in RCA: 57] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Accepted: 08/10/2021] [Indexed: 12/12/2022] Open
Abstract
Bacteria have evolved many different signal transduction systems that sense signals and generate a variety of responses. Generally, most abundant are transcriptional regulators, sensor histidine kinases and chemoreceptors. Typically, these systems recognize their signal molecules with dedicated ligand-binding domains (LBDs), which, in turn, generate a molecular stimulus that modulates the activity of the output module. There are an enormous number of different LBDs that recognize a similarly diverse set of signals. To give a global perspective of the signals that interact with transcriptional regulators, sensor kinases and chemoreceptors, we manually retrieved information on the protein-ligand interaction from about 1,200 publications and 3D structures. The resulting 811 proteins were classified according to the Pfam family into 127 groups. These data permit a delineation of the signal profiles of individual LBD families as well as distinguishing between families that recognize signals in a promiscuous manner and those that possess a well-defined ligand range. A major bottleneck in the field is the fact that the signal input of many signaling systems is unknown. The signal repertoire reported here will help the scientific community design experimental strategies to identify the signaling molecules for uncharacterised sensor proteins.
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Affiliation(s)
- Miguel A Matilla
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Prof. Albareda 1, 18008 Granada, Spain
| | - Félix Velando
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Prof. Albareda 1, 18008 Granada, Spain
| | - David Martín-Mora
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Prof. Albareda 1, 18008 Granada, Spain
| | - Elizabet Monteagudo-Cascales
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Prof. Albareda 1, 18008 Granada, Spain
| | - Tino Krell
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Prof. Albareda 1, 18008 Granada, Spain
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Li Y, Liang J, Yang S, Yao J, Chen K, Yang L, Zheng W, Tian Y. Finding novel chemoreceptors that specifically sense and trigger chemotaxis toward polycyclic aromatic hydrocarbons in Novosphingobium pentaromativorans US6-1. JOURNAL OF HAZARDOUS MATERIALS 2021; 416:126246. [PMID: 34492992 DOI: 10.1016/j.jhazmat.2021.126246] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 05/22/2021] [Accepted: 05/25/2021] [Indexed: 06/13/2023]
Abstract
Bacterial chemotaxis can improve the efficiency of aromatic compound degradation, however, knowledge of how bacteria sense high-molecular-weight polycyclic aromatic hydrocarbons (HMW-PAHs), is limited. Here, the chemotactic responses of Novosphingobium pentaromativorans US6-1 to 9 aromatic compounds were investigated. The results showed that US6-1 chemotactically responded to phenanthrene (PHE), pyrene (PYR), benzo[a]pyrene (BaP) and their six metabolites. Six methyl-accepting chemotaxis proteins (MCPs) were annotated from US6-1 genome, four of which contained putative ligand-binding domains (LBDs). To confirm whether these four MCPs were involved in triggering chemotaxis toward PAHs, the MCP mutants were constructed. Observations showed a loss of the chemotactic responses to benzoate, phthalate, PHE and BaP only in the mutant ∆mcp03030. Surface plasmon resonance (SPR) assays further confirmed that MCP03030LBD specifically bound phthalate, PHE, PYR and BaP, while MCP18870LBD bound only PYR. The mutant ∆mcp03030-∆mcp18870 was then constructed and was shown to have lost the chemotactic response to 5 aromatic compounds. Combined with the effects of outer membrane transporter deletion on chemotaxis and MCP deletion on the PAH degradation, our study demonstrated that the chemoreceptors MCP03030 and MCP18870 can recognize PAHs and their metabolites in the periplasm, triggering metabolism-dependent and metabolism-independent chemotaxis, and be linked with HMW-PAH biodegradation.
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Affiliation(s)
- Yuqian Li
- Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen 361102, China
| | - Jiaqing Liang
- Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen 361102, China
| | - Shuyue Yang
- Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen 361102, China
| | - Jiebin Yao
- Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen 361102, China
| | - Kai Chen
- Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen 361102, China
| | - Luxi Yang
- Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen 361102, China
| | - Wei Zheng
- Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen 361102, China
| | - Yun Tian
- Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen 361102, China; State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361102, China
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The Divergent Key Residues of Two Agrobacterium fabrum ( tumefaciens) CheY Paralogs Play a Key Role in Distinguishing Their Functions. Microorganisms 2021; 9:microorganisms9061134. [PMID: 34074050 PMCID: PMC8225110 DOI: 10.3390/microorganisms9061134] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 05/21/2021] [Accepted: 05/22/2021] [Indexed: 11/23/2022] Open
Abstract
The chemotactic response regulator CheY, when phosphorylated by the phosphoryl group from phosphorylated CheA, can bind to the motor switch complex to control the flagellar motor rotation. Agrobacterium fabrum (previous name: Agrobacterium tumefaciens), a phytopathogen, carries two paralogous cheY genes, cheY1 and cheY2. The functional difference of two paralogous CheYs remains unclear. Three cheY-deletion mutants were constructed to test the effects of two CheYs on the chemotaxis of A.fabrum. Phenotypes of three cheY-deletion mutants show that deletion of each cheY significantly affects the chemotactic response, but cheY2-deletion possesses more prominent effects on the chemotactic migration and swimming pattern of A. fabrum than does cheY1-deletion. CheA-dependent cellular localization of two CheY paralogs and in vitro pull-down of two CheY paralogs by FliM demonstrate that the distinct roles of two CheY paralogs arise mainly from the differentiation of their binding affinities for the motor switch component FliM, agreeing with the divergence of the key residues on the motor-binding surface involved in the interaction with FliM. The single respective replacements of key residues R93 and A109 on the motor-binding surface of CheY2 by alanine (A) and valine (V), the corresponding residues of CheY1, significantly enhanced the function of CheY2 in regulating the chemotactic response of A. fabrum CheY-deficient mutant Δy to nutrient substances and host attractants. These results conclude that the divergence of the key residues in the functional subdomain is the decisive factor of functional differentiation of these two CheY homologs and protein function may be improved by the substitution of the divergent key residues in the functional domain for the corresponding residues of its paralogs. This finding will help us to better understand how paralogous proteins sub-functionalize. In addition, the acquirement of two CheY2 variants, whose chemotactic response functions are significantly improved, will be very useful for us to further explore the mechanism of CheY to bind and regulate the flagellar motor and the role of chemotaxis in the pathogenicity of A. fabrum.
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Tumewu SA, Ogawa Y, Okamoto T, Sugihara Y, Yamada H, Taguchi F, Matsui H, Yamamoto M, Noutoshi Y, Toyoda K, Ichinose Y. Cluster II che genes of Pseudomonas syringae pv. tabaci 6605, orthologs of cluster I in Pseudomonas aeruginosa, are required for chemotaxis and virulence. Mol Genet Genomics 2021; 296:299-312. [PMID: 33386986 DOI: 10.1007/s00438-020-01745-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 11/09/2020] [Indexed: 12/19/2022]
Abstract
Pseudomonas syringae pv. tabaci 6605 (Pta6605) is a causal agent of wildfire disease in host tobacco plants and is highly motile. Pta6605 has multiple clusters of chemotaxis genes including cheA, a gene encoding a histidine kinase, cheY, a gene encoding a response regulator, mcp, a gene for a methyl-accepting chemotaxis protein, as well as flagellar and pili biogenesis genes. However, only two major chemotaxis gene clusters, cluster I and cluster II, possess cheA and cheY. Deletion mutants of cheA or cheY were constructed to evaluate their possible role in Pta6605 chemotaxis and virulence. Motility tests and a chemotaxis assay to known attractant demonstrated that cheA2 and cheY2 mutants were unable to swarm and to perform chemotaxis, whereas cheA1 and cheY1 mutants retained chemotaxis ability almost equal to that of the wild-type (WT) strain. Although WT and cheY1 mutants of Pta6605 caused severe disease symptoms on host tobacco leaves, the cheA2 and cheY2 mutants did not, and symptom development with cheA1 depended on the inoculation method. These results indicate that chemotaxis genes located in cluster II are required for optimal chemotaxis and host plant infection by Pta6605 and that cluster I may partially contribute to these phenotypes.
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Affiliation(s)
- Stephany Angelia Tumewu
- Graduate School of Environmental and Life Science, Okayama University, Tsushima-naka 1-1-1, Kita-ku, Okayama, 700-8530, Japan
| | - Yujiro Ogawa
- Faculty of Agriculture, Okayama University, Tsushima-naka 1-1-1, Kita-ku, Okayama, 700-8530, Japan
| | - Takumi Okamoto
- Faculty of Agriculture, Okayama University, Tsushima-naka 1-1-1, Kita-ku, Okayama, 700-8530, Japan
| | - Yuka Sugihara
- Faculty of Agriculture, Okayama University, Tsushima-naka 1-1-1, Kita-ku, Okayama, 700-8530, Japan
| | - Hajime Yamada
- Faculty of Agriculture, Okayama University, Tsushima-naka 1-1-1, Kita-ku, Okayama, 700-8530, Japan
| | - Fumiko Taguchi
- Graduate School of Environmental and Life Science, Okayama University, Tsushima-naka 1-1-1, Kita-ku, Okayama, 700-8530, Japan
- Department of Biotechnology, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8603, Japan
| | - Hidenori Matsui
- Graduate School of Environmental and Life Science, Okayama University, Tsushima-naka 1-1-1, Kita-ku, Okayama, 700-8530, Japan
| | - Mikihiro Yamamoto
- Graduate School of Environmental and Life Science, Okayama University, Tsushima-naka 1-1-1, Kita-ku, Okayama, 700-8530, Japan
| | - Yoshiteru Noutoshi
- Graduate School of Environmental and Life Science, Okayama University, Tsushima-naka 1-1-1, Kita-ku, Okayama, 700-8530, Japan
| | - Kazuhiro Toyoda
- Graduate School of Environmental and Life Science, Okayama University, Tsushima-naka 1-1-1, Kita-ku, Okayama, 700-8530, Japan
| | - Yuki Ichinose
- Graduate School of Environmental and Life Science, Okayama University, Tsushima-naka 1-1-1, Kita-ku, Okayama, 700-8530, Japan.
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11
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Zboralski A, Filion M. Genetic factors involved in rhizosphere colonization by phytobeneficial Pseudomonas spp. Comput Struct Biotechnol J 2020; 18:3539-3554. [PMID: 33304453 PMCID: PMC7711191 DOI: 10.1016/j.csbj.2020.11.025] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 11/10/2020] [Accepted: 11/12/2020] [Indexed: 12/13/2022] Open
Abstract
Plant growth-promoting rhizobacteria (PGPR) actively colonize the soil portion under the influence of plant roots, called the rhizosphere. Many plant-beneficial Pseudomonas spp. have been characterized as PGPR. They are ubiquitous rod-shaped motile Gram-negative bacteria displaying a high metabolic versatility. Their capacity to protect plants from pathogens and improve plant growth closely depends on their rhizosphere colonization abilities. Various molecular and cellular mechanisms are involved in this complex process, such as chemotaxis, biofilm formation, secondary metabolites biosynthesis, metabolic versatility, and evasion of plant immunity. The burst in Pseudomonas spp. genome sequencing in recent years has been crucial to better understand how they colonize the rhizosphere. In this review, we discuss the recent advances regarding these mechanisms and the underlying bacterial genetic factors required for successful rhizosphere colonization.
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Affiliation(s)
- Antoine Zboralski
- Department of Biology, Université de Moncton, Moncton, NB E1A 3E9, Canada
| | - Martin Filion
- Research and Development Centre, Agriculture and Agri-Food Canada, Saint-Jean-sur-Richelieu, QC J3B 3E6, Canada
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12
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Xu N, Wang M, Yang X, Xu Y, Guo M. In silico analysis of the chemotactic system of Agrobacterium tumefaciens. Microb Genom 2020; 6:mgen000460. [PMID: 33118922 PMCID: PMC7725337 DOI: 10.1099/mgen.0.000460] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 10/06/2020] [Indexed: 01/23/2023] Open
Abstract
Agrobacterium tumefaciens is an efficient tool for creating transgenic host plants. The first step in the genetic transformation process involves A. tumefaciens chemotaxis, which is crucial to the survival of A. tumefaciens in changeable, harsh and even contaminated soil environments. However, a systematic study of its chemotactic signalling pathway is still lacking. In this study, the distribution and classification of chemotactic genes in the model A. tumefaciens C58 and 21 other strains were annotated. Local blast was used for comparative genomics, and hmmer was used for predicting protein domains. Chemotactic phenotypes for knockout mutants of ternary signalling complexes in A. tumefaciens C58 were evaluated using a swim agar plate. A major cluster, in which chemotaxis genes were consistently organized as MCP (methyl-accepting chemotaxis protein), CheS, CheY1, CheA, CheR, CheB, CheY2 and CheD, was found in A. tumefaciens, but two coupling CheW proteins were located outside the 'che' cluster. In the ternary signalling complexes, the absence of MCP atu0514 significantly impaired A. tumefaciens chemotaxis, and the absence of CheA (atu0517) or the deletion of both CheWs abolished chemotaxis. A total of 465 MCPs were found in the 22 strains, and the cytoplasmic domains of these MCPs were composed of 38 heptad repeats. A high homology was observed between the chemotactic systems of the 22 A. tumefaciens strains with individual differences in the gene and receptor protein distributions, possibly related to their ecological niches. This preliminary study demonstrates the chemotactic system of A. tumefaciens, and provides some reference for A. tumefaciens sensing and chemotaxis to exogenous signals.
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Affiliation(s)
- Nan Xu
- College of Bioscience and Biotechnology, Yangzhou University, Yangzhou 225009, PR China
- Joint International Research Laboratory of Agriculture and Agri-Product Safety, The Ministry of Education of China, Yangzhou University, Yangzhou 225009, PR China
| | - Mingqi Wang
- College of Bioscience and Biotechnology, Yangzhou University, Yangzhou 225009, PR China
- Joint International Research Laboratory of Agriculture and Agri-Product Safety, The Ministry of Education of China, Yangzhou University, Yangzhou 225009, PR China
| | - Xiaojing Yang
- College of Bioscience and Biotechnology, Yangzhou University, Yangzhou 225009, PR China
- Joint International Research Laboratory of Agriculture and Agri-Product Safety, The Ministry of Education of China, Yangzhou University, Yangzhou 225009, PR China
| | - Yujuan Xu
- College of Bioscience and Biotechnology, Yangzhou University, Yangzhou 225009, PR China
- Joint International Research Laboratory of Agriculture and Agri-Product Safety, The Ministry of Education of China, Yangzhou University, Yangzhou 225009, PR China
| | - Minliang Guo
- College of Bioscience and Biotechnology, Yangzhou University, Yangzhou 225009, PR China
- Joint International Research Laboratory of Agriculture and Agri-Product Safety, The Ministry of Education of China, Yangzhou University, Yangzhou 225009, PR China
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13
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Guo L, Wang J, Gou Y, Tan L, Liu H, Pan Y, Zhao Y. Comparative proteomics reveals stress responses of Vibrio parahaemolyticus biofilm on different surfaces: Internal adaptation and external adjustment. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 731:138386. [PMID: 32417469 DOI: 10.1016/j.scitotenv.2020.138386] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 03/27/2020] [Accepted: 03/31/2020] [Indexed: 06/11/2023]
Abstract
Vibrio parahaemolyticus is a kind of gram-negative marine pathogen, which usually adheres to stainless steel (SS), glass (GS) and other abiotic surfaces in aquaculture and food processing in the form of biofilm and causes the spread of gastrointestinal illness. However, the deeply survival adaptation mechanism of V. parahaemolyticus biofilm cells on these contact surface remained unclear. Here, proteomics was used to investigated the physiological response of the V. parahaemolyticus biofilms cells to different abiotic surfaces (SS, GS and polystyrene (PS)). In addition, the effect of contact materials on the physical-chemical properties of biofilms are also characterized. Results showed that the expression of proteins of biofilm cells established on the SS surface were mainly related to the alleviation of metal ion stress and toxicity. The up-regulated proteins in the biofilm cells formed on the GS surface were mainly involved in the biological processes of sugar uptake, protein synthesis and bacterial chemotaxis. Meanwhile, the significantly expressed proteins in the biofilm cells formed on the PS surface were mainly involved in the cellular physiological activity of aromatic compound metabolism, osmotic stress and nutrient transport. All functional proteins mentioned above were closely related to the interaction characteristics of the contact surface and biofilm. This study provided an in-depth comparison of V. parahaemolyticus biofilm formation on these three abiotic surfaces, and presented a model in first time for the adaptation behavior of biofilm cells on different surfaces as affected by metal ion stress, nutrition, osmotic stress, and sugar utilization, which could facilitate an efficient control strategy for biofilm formation in industrial field.
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Affiliation(s)
- Linxia Guo
- College of Food Science & Technology, Shanghai Ocean University, Shanghai, China
| | - Jingjing Wang
- College of Food Science & Technology, Shanghai Ocean University, Shanghai, China; Laboratory of Quality and Safety Risk Assessment for Aquatic Products on Storage and Preservation (Shanghai), Ministry of Agriculture, Shanghai, China; Shanghai Engineering Research Center of Aquatic-Product Processing & Preservation, Shanghai, China; Department of Food Science, Foshan University, Foshan, 528000, China
| | - Yi Gou
- College of Food Science & Technology, Shanghai Ocean University, Shanghai, China
| | - Ling Tan
- College of Food Science & Technology, Shanghai Ocean University, Shanghai, China
| | - Haiquan Liu
- College of Food Science & Technology, Shanghai Ocean University, Shanghai, China; Laboratory of Quality and Safety Risk Assessment for Aquatic Products on Storage and Preservation (Shanghai), Ministry of Agriculture, Shanghai, China; Shanghai Engineering Research Center of Aquatic-Product Processing & Preservation, Shanghai, China; Engineering Research Center of Food Thermal-processing Technology, Shanghai Ocean University, Shanghai 201306, China
| | - Yingjie Pan
- College of Food Science & Technology, Shanghai Ocean University, Shanghai, China; Laboratory of Quality and Safety Risk Assessment for Aquatic Products on Storage and Preservation (Shanghai), Ministry of Agriculture, Shanghai, China; Shanghai Engineering Research Center of Aquatic-Product Processing & Preservation, Shanghai, China
| | - Yong Zhao
- College of Food Science & Technology, Shanghai Ocean University, Shanghai, China; Laboratory of Quality and Safety Risk Assessment for Aquatic Products on Storage and Preservation (Shanghai), Ministry of Agriculture, Shanghai, China; Shanghai Engineering Research Center of Aquatic-Product Processing & Preservation, Shanghai, China.
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14
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Arapov TD, Saldaña RC, Sebastian AL, Ray WK, Helm RF, Scharf BE. Cellular Stoichiometry of Chemotaxis Proteins in Sinorhizobium meliloti. J Bacteriol 2020; 202:e00141-20. [PMID: 32393521 PMCID: PMC7317046 DOI: 10.1128/jb.00141-20] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Accepted: 05/05/2020] [Indexed: 11/20/2022] Open
Abstract
Chemotaxis systems enable microbes to sense their immediate environment, moving toward beneficial stimuli and away from those that are harmful. In an effort to better understand the chemotaxis system of Sinorhizobium meliloti, a symbiont of the legume alfalfa, the cellular stoichiometries of all ten chemotaxis proteins in S. meliloti were determined. A combination of quantitative immunoblot and mass spectrometry revealed that the protein stoichiometries in S. meliloti varied greatly from those in Escherichia coli and Bacillus subtilis To compare protein ratios to other systems, values were normalized to the central kinase CheA. All S. meliloti chemotaxis proteins exhibited increased ratios to various degrees. The 10-fold higher molar ratio of adaptor proteins CheW1 and CheW2 to CheA might result in the formation of rings in the chemotaxis array that consist of only CheW instead of CheA and CheW in a 1:1 ratio. We hypothesize that the higher ratio of CheA to the main response regulator CheY2 is a consequence of the speed-variable motor in S. meliloti, instead of a switch-type motor. Similarly, proteins involved in signal termination are far more abundant in S. meliloti, which utilizes a phosphate sink mechanism based on CheA retrophosphorylation to inactivate the motor response regulator versus CheZ-catalyzed dephosphorylation as in E. coli and B. subtilis Finally, the abundance of CheB and CheR, which regulate chemoreceptor methylation, was increased compared to CheA, indicative of variations in the adaptation system of S. meliloti Collectively, these results mark significant differences in the composition of bacterial chemotaxis systems.IMPORTANCE The symbiotic soil bacterium Sinorhizobium meliloti contributes greatly to host-plant growth by fixing atmospheric nitrogen. The provision of nitrogen as ammonium by S. meliloti leads to increased biomass production of its legume host alfalfa and diminishes the use of environmentally harmful chemical fertilizers. To better understand the role of chemotaxis in host-microbe interaction, a comprehensive catalogue of the bacterial chemotaxis system is vital, including its composition, function, and regulation. The stoichiometry of chemotaxis proteins in S. meliloti has very few similarities to the systems in Escherichia coli and Bacillus subtilis In addition, total amounts of proteins are significantly lower. S. meliloti exhibits a chemotaxis system distinct from known models by incorporating new proteins as exemplified by the phosphate sink mechanism.
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Affiliation(s)
- Timofey D Arapov
- Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA
| | | | - Amanda L Sebastian
- Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA
| | - W Keith Ray
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, USA
| | - Richard F Helm
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, USA
| | - Birgit E Scharf
- Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA
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15
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Frutos-Grilo E, Marsal M, Irazoki O, Barbé J, Campoy S. The Interaction of RecA With Both CheA and CheW Is Required for Chemotaxis. Front Microbiol 2020; 11:583. [PMID: 32318049 PMCID: PMC7154110 DOI: 10.3389/fmicb.2020.00583] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 03/17/2020] [Indexed: 12/20/2022] Open
Abstract
Salmonella enterica is the most frequently reported cause of foodborne illness. As in other microorganisms, chemotaxis affords key physiological benefits, including enhanced access to growth substrates, but also plays an important role in infection and disease. Chemoreceptor signaling core complexes, consisting of CheA, CheW and methyl-accepting chemotaxis proteins (MCPs), modulate the switching of bacterial flagella rotation that drives cell motility. These complexes, through the formation of heterohexameric rings composed of CheA and CheW, form large clusters at the cell poles. RecA plays a key role in polar cluster formation, impairing the assembly when the SOS response is activated. In this study, we determined that RecA protein interacts with both CheW and CheA. The binding of these proteins to RecA is needed for wild-type polar cluster formation. In silico models showed that one RecA molecule, attached to one signaling unit, fits within a CheA-CheW ring without interfering with the complex formation or array assembly. Activation of the SOS response is followed by an increase in RecA, which rises up the number of signaling complexes associated with this protein. This suggests the presence of allosteric inhibition in the CheA-CheW interaction and thus of heterohexameric ring formation, impairing the array assembly. STED imaging demonstrated that all core unit components (CheA, CheW, and MPCs) have the same subcellular location as RecA. Activation of the SOS response promotes the RecA distribution along the cell instead of being at the cell poles. CheA- and CheW- RecA interactions are also crucial for chemotaxis, which is maintained when the SOS response is induced and the signaling units are dispersed. Our results provide new molecular-level insights into the function of RecA in chemoreceptor clustering and chemotaxis determining that the impaired chemoreceptor clustering not only inhibits swarming but also modulates chemotaxis in SOS-induced cells, thereby modifying bacterial motility in the presence of DNA-damaging compounds, such as antibiotics.
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Affiliation(s)
- Elisabet Frutos-Grilo
- Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Maria Marsal
- ICFO-Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Oihane Irazoki
- Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Jordi Barbé
- Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Susana Campoy
- Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, Barcelona, Spain
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16
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Tumewu SA, Matsui H, Yamamoto M, Noutoshi Y, Toyoda K, Ichinose Y. Requirement of γ-Aminobutyric Acid Chemotaxis for Virulence of Pseudomonas syringae pv. tabaci 6605. Microbes Environ 2020; 35:ME20114. [PMID: 33162464 PMCID: PMC7734410 DOI: 10.1264/jsme2.me20114] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 09/15/2020] [Indexed: 12/04/2022] Open
Abstract
γ-Aminobutyric acid (GABA) is a widely distributed non-proteinogenic amino acid that accumulates in plants under biotic and abiotic stress conditions. Recent studies suggested that GABA also functions as an intracellular signaling molecule in plants and in signals mediating interactions between plants and phytopathogenic bacteria. However, the molecular mechanisms underlying GABA responses to bacterial pathogens remain unknown. In the present study, a GABA receptor, named McpG, was conserved in the highly motile plant-pathogenic bacteria Pseudomonas syringae pv. tabaci 6605 (Pta6605). We generated a deletion mutant of McpG to further investigate its involvement in GABA chemotaxis using quantitative capillary and qualitative plate assays. The wild-type strain of Pta6605 was attracted to GABA, while the ΔmcpG mutant abolished chemotaxis to 10 mM GABA. However, ΔmcpG retained chemotaxis to proteinogenic amino acids and succinic semialdehyde, a structural analog of GABA. Furthermore, ΔmcpG was unable to effectively induce disease on host tobacco plants in three plant inoculation assays: flood, dip, and infiltration inoculations. These results revealed that the GABA sensing of Pta6605 is important for the interaction of Pta6605 with its host tobacco plant.
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Affiliation(s)
- Stephany Angelia Tumewu
- Graduate School of Environmental and Life Science, Okayama University, Tsushima-naka 1–1–1, Kita-ku, Okayama 700–8530, Japan
| | - Hidenori Matsui
- Graduate School of Environmental and Life Science, Okayama University, Tsushima-naka 1–1–1, Kita-ku, Okayama 700–8530, Japan
| | - Mikihiro Yamamoto
- Graduate School of Environmental and Life Science, Okayama University, Tsushima-naka 1–1–1, Kita-ku, Okayama 700–8530, Japan
| | - Yoshiteru Noutoshi
- Graduate School of Environmental and Life Science, Okayama University, Tsushima-naka 1–1–1, Kita-ku, Okayama 700–8530, Japan
| | - Kazuhiro Toyoda
- Graduate School of Environmental and Life Science, Okayama University, Tsushima-naka 1–1–1, Kita-ku, Okayama 700–8530, Japan
| | - Yuki Ichinose
- Graduate School of Environmental and Life Science, Okayama University, Tsushima-naka 1–1–1, Kita-ku, Okayama 700–8530, Japan
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17
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Padilla-Vaca F, Vargas-Maya NI, Elizarrarás-Vargas NU, Rangel-Serrano Á, Cardoso-Reyes LR, Razo-Soria T, Membrillo-Hernández J, Franco B. Flotillin homologue is involved in the swimming behavior of Escherichia coli. Arch Microbiol 2019; 201:999-1008. [PMID: 31062059 DOI: 10.1007/s00203-019-01670-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 04/22/2019] [Accepted: 04/24/2019] [Indexed: 01/22/2023]
Abstract
Cellular membrane is a key component for maintaining cell shape and integrity. The classical membrane structure and function by Singer and Nicolson groundbreaking model has depicted the membrane as a homogeneous fluid structure. This view has changed by the discovery of discrete domains containing different lipid compositions, called lipid rafts, which play a key role in signal transduction in eukaryotic cells. In the past few years, lipid raft-like structures have been found in bacteria also, constituted by cardiolipin and other modified lipids, perhaps involved in generating a specific site for protein clustering. Here, we report the analysis of a protein termed YqiK from Escherichia coli, a prohibitin homolog that has been implicated in stress sensing by the formation of membrane-associated microdomains. The E. coli yqiK-deficient mutant strain showed an enhanced swimming behavior and was resistant to ampicillin but its response to other stressing conditions was similar to that of the wild-type strain. The abnormal swimming behavior is reversed when the protein is expressed in trans from a plasmid. Also, we demonstrate that YqiK is not redundant with QmcA, another flotillin homolog found in E. coli. Our results, along with the data available in the literature, suggest that YqiK may be involved in the formation of discrete membrane-associated signaling complexes that regulate and agglomerate signaling proteins to generate cell response to chemotaxis.
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Affiliation(s)
- Felipe Padilla-Vaca
- División de Ciencias Naturales y Exactas, Departamento de Biología, Universidad de Guanajuato, Noria Alta s/n, Guanajuato, Gto, 36050, Mexico
| | - Naurú Idalia Vargas-Maya
- División de Ciencias Naturales y Exactas, Departamento de Biología, Universidad de Guanajuato, Noria Alta s/n, Guanajuato, Gto, 36050, Mexico
| | - Narciso Ulises Elizarrarás-Vargas
- División de Ciencias Naturales y Exactas, Departamento de Biología, Universidad de Guanajuato, Noria Alta s/n, Guanajuato, Gto, 36050, Mexico
| | - Ángeles Rangel-Serrano
- División de Ciencias Naturales y Exactas, Departamento de Biología, Universidad de Guanajuato, Noria Alta s/n, Guanajuato, Gto, 36050, Mexico
| | - Luis Rafael Cardoso-Reyes
- División de Ciencias Naturales y Exactas, Departamento de Biología, Universidad de Guanajuato, Noria Alta s/n, Guanajuato, Gto, 36050, Mexico
| | - Tannia Razo-Soria
- División de Ciencias Naturales y Exactas, Departamento de Biología, Universidad de Guanajuato, Noria Alta s/n, Guanajuato, Gto, 36050, Mexico
| | - Jorge Membrillo-Hernández
- Departamento de Bioingeniería, Escuela de Ingeniería y Ciencias, Tecnológico de Monterrey, Monterrey, Mexico
| | - Bernardo Franco
- División de Ciencias Naturales y Exactas, Departamento de Biología, Universidad de Guanajuato, Noria Alta s/n, Guanajuato, Gto, 36050, Mexico.
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18
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Bacterial chemotaxis coupling protein: Structure, function and diversity. Microbiol Res 2019; 219:40-48. [DOI: 10.1016/j.micres.2018.11.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 10/29/2018] [Accepted: 11/02/2018] [Indexed: 01/10/2023]
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19
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Feng H, Zhang N, Fu R, Liu Y, Krell T, Du W, Shao J, Shen Q, Zhang R. Recognition of dominant attractants by key chemoreceptors mediates recruitment of plant growth-promoting rhizobacteria. Environ Microbiol 2019; 21:402-415. [PMID: 30421582 DOI: 10.1111/1462-2920.14472] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2018] [Revised: 10/09/2018] [Accepted: 11/05/2018] [Indexed: 12/16/2022]
Abstract
Chemotaxis to plant root exudates is supposed to be a prerequisite for efficient root colonization by rhizobacteria. This is a highly multifactorial process since root exudates are complex compound mixtures of which components are recognized by different chemoreceptors. Little information is available as to the key components in root exudates and their receptors that drive colonization related chemotaxis. We present here the first global assessment of this issue using the plant growth-promoting rhizobacterium (PGPR) Bacillus velezensis SQR9 (formerly B. amyloliquefaciens). This strain efficiently colonizes cucumber roots, and here, we show that chemotaxis to cucumber root exudates was essential in this process. We conducted chemotaxis assays using cucumber root exudates at different concentrations, individual exudate components as well as recomposed exudates, taking into account their concentrations detected in root exudates. Results indicated that two key chemoreceptors, McpA and McpC, were essential for root exudate chemotaxis and root colonization. Both receptors possess a broad ligand range and recognize most of the exudate key components identified (malic, fumaric, gluconic and glyceric acids, Lys, Ser, Ala and mannose). The remaining six chemoreceptors did not contribute to exudate chemotaxis. This study provides novel insight into the evolution of the chemotaxis system in rhizobacteria.
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Affiliation(s)
- Haichao Feng
- Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing, 210095, China.,Key Laboratory of Microbial Resources Collection and Preservation, Ministry of Agriculture, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Nan Zhang
- Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing, 210095, China
| | - Ruixin Fu
- Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing, 210095, China
| | - Yunpeng Liu
- Key Laboratory of Microbial Resources Collection and Preservation, Ministry of Agriculture, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Tino Krell
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, 18008, Granada, Spain
| | - Wenbin Du
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Jiahui Shao
- Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing, 210095, China
| | - Qirong Shen
- Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing, 210095, China
| | - Ruifu Zhang
- Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing, 210095, China.,Key Laboratory of Microbial Resources Collection and Preservation, Ministry of Agriculture, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
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20
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Sinorhizobium meliloti Chemoreceptor McpV Senses Short-Chain Carboxylates via Direct Binding. J Bacteriol 2018; 200:JB.00519-18. [PMID: 30201781 DOI: 10.1128/jb.00519-18] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Accepted: 09/04/2018] [Indexed: 11/20/2022] Open
Abstract
Sinorhizobium meliloti is a soil-dwelling endosymbiont of alfalfa that has eight chemoreceptors to sense environmental stimuli during its free-living state. The functions of two receptors have been characterized, with McpU and McpX serving as general amino acid and quaternary ammonium compound sensors, respectively. Both receptors use a dual Cache (calcium channels and chemotaxis receptors) domain for ligand binding. We identified that the ligand-binding periplasmic region (PR) of McpV contains a single Cache domain. Homology modeling revealed that McpVPR is structurally similar to a sensor domain of a chemoreceptor with unknown function from Anaeromyxobacter dehalogenans, which crystallized with acetate in its binding pocket. We therefore assayed McpV for carboxylate binding and S. meliloti for carboxylate sensing. Differential scanning fluorimetry identified 10 potential ligands for McpVPR Nine of these are monocarboxylates with chain lengths between two and four carbons. We selected seven compounds for capillary assay analysis, which established positive chemotaxis of the S. meliloti wild type, with concentrations of peak attraction at 1 mM for acetate, propionate, pyruvate, and glycolate, and at 100 mM for formate and acetoacetate. Deletion of mcpV or mutation of residues essential for ligand coordination abolished positive chemotaxis to carboxylates. Using microcalorimetry, we determined that dissociation constants of the seven ligands with McpVPR were in the micromolar range. An McpVPR variant with a mutation in the ligand coordination site displayed no binding to isobutyrate or propionate. Of all the carboxylates tested as attractants, only glycolate was detected in alfalfa seed exudates. This work examines the relevance of carboxylates and their sensor to the rhizobium-legume interaction.IMPORTANCE Legumes share a unique association with certain soil-dwelling bacteria known broadly as rhizobia. Through concerted interorganismal communication, a legume allows intracellular infection by its cognate rhizobial species. The plant then forms an organ, the root nodule, dedicated to housing and supplying fixed carbon and nutrients to the bacteria. In return, the engulfed rhizobia, differentiated into bacteroids, fix atmospheric N2 into ammonium for the plant host. This interplay is of great benefit to the cultivation of legumes, such as alfalfa and soybeans, and is initiated by chemotaxis to the host plant. This study on carboxylate chemotaxis contributes to the understanding of rhizobial survival and competition in the rhizosphere and aids the development of commercial inoculants.
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21
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Thomas MA, Kleist AB, Volkman BF. Decoding the chemotactic signal. J Leukoc Biol 2018; 104:359-374. [PMID: 29873835 PMCID: PMC6099250 DOI: 10.1002/jlb.1mr0218-044] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Accepted: 02/25/2018] [Indexed: 12/20/2022] Open
Abstract
From an individual bacterium to the cells that compose the human immune system, cellular chemotaxis plays a fundamental role in allowing cells to navigate, interpret, and respond to their environments. While many features of cellular chemotaxis are shared among systems as diverse as bacteria and human immune cells, the machinery that guides the migration of these model organisms varies widely. In this article, we review current literature on the diversity of chemoattractant ligands, the cell surface receptors that detect and process chemotactic gradients, and the link between signal recognition and the regulation of cellular machinery that allow for efficient directed cellular movement. These facets of cellular chemotaxis are compared among E. coli, Dictyostelium discoideum, and mammalian neutrophils to derive organizational principles by which diverse cell systems sense and respond to chemotactic gradients to initiate cellular migration.
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Affiliation(s)
- Monica A. Thomas
- Department of BiochemistryMedical College of WisconsinMilwaukeeWisconsinUSA
| | - Andrew B. Kleist
- Department of BiochemistryMedical College of WisconsinMilwaukeeWisconsinUSA
| | - Brian F. Volkman
- Department of BiochemistryMedical College of WisconsinMilwaukeeWisconsinUSA
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22
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Huang Z, Zhou Q, Sun P, Yang J, Guo M. Two Agrobacterium tumefaciens CheW Proteins Are Incorporated into One Chemosensory Pathway with Different Efficiencies. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2018; 31:460-470. [PMID: 29182466 DOI: 10.1094/mpmi-10-17-0255-r] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Agrobacterium tumefaciens is the agent that causes crown gall tumor disease on more than 140 species of dicotyledonous plants. Chemotaxis of A. tumefaciens toward the wound sites of the host plant is the first step to recognize the host. CheW is a coupling protein that bridges the histidine kinase CheA and the chemoreceptors to form the chemotaxis core signaling complex and plays a crucial role in the assembly and function of the large chemosensory array. Unlike all previously reported chemotaxis systems, A. tumefaciens has only one major che operon but two cheW homologs (atu2075 as cheW1 and atu2617 as cheW2) on unlinked loci. The in-frame deletion of either cheW gene significantly affects A. tumefaciens chemotaxis but does not abolish the chemotaxis, unless both cheW genes were deleted. The effect of cheW2 deletion on the chemotaxis is more severe than that of cheW1 deletion. Either CheW can interact with CheA and couple it to the cell poles. The promoter activity of cheW2 is always higher than that of cheW1 under all of the tested conditions. When two cheW genes were adjusted to the same expression level by using the identical promoter, the difference between the effects of two CheW proteins on the chemotaxis still existed. Therefore, we envision that both the different molecular ratio of two CheW proteins in cell and the different affinities of two CheW proteins with CheA and chemoreceptors result in the efficiency difference of two CheW proteins in functioning in the large chemosensory array.
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Affiliation(s)
- Zhiwei Huang
- College of Bioscience and Biotechnology, Yangzhou University, Yangzhou City, Jiangsu 225009, P R China
| | - Qingxuan Zhou
- College of Bioscience and Biotechnology, Yangzhou University, Yangzhou City, Jiangsu 225009, P R China
| | - Pan Sun
- College of Bioscience and Biotechnology, Yangzhou University, Yangzhou City, Jiangsu 225009, P R China
| | - Jing Yang
- College of Bioscience and Biotechnology, Yangzhou University, Yangzhou City, Jiangsu 225009, P R China
| | - Minliang Guo
- College of Bioscience and Biotechnology, Yangzhou University, Yangzhou City, Jiangsu 225009, P R China
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23
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Bi S, Sourjik V. Stimulus sensing and signal processing in bacterial chemotaxis. Curr Opin Microbiol 2018; 45:22-29. [PMID: 29459288 DOI: 10.1016/j.mib.2018.02.002] [Citation(s) in RCA: 136] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 01/30/2018] [Accepted: 02/02/2018] [Indexed: 11/25/2022]
Abstract
Motile bacteria use chemotaxis to migrate towards environments that are favorable for growth and survival. The signaling pathway that mediates this behavior is largely conserved among prokaryotes, with Escherichia coli chemotaxis system being one of the simplest and the best studied. At the core of this pathway are the arrays of clustered chemoreceptors that detect, amplify and integrate various stimuli. Recent work provided deeper understanding of spatial organization and signal processing by these clusters and uncovered the variety of sensory mechanisms used to detect environmental stimuli. Moreover, studies of bacteria with different lifestyles have led to new insights into the diversity and evolutionary conservation of the chemotaxis pathway, as well as the physiological relevance of chemotactic behavior in different environments.
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Affiliation(s)
- Shuangyu Bi
- Max Planck Institute for Terrestrial Microbiology and LOEWE Center for Synthetic Microbiology, Karl-von-Frisch-Strasse 16, 35043 Marburg, Germany
| | - Victor Sourjik
- Max Planck Institute for Terrestrial Microbiology and LOEWE Center for Synthetic Microbiology, Karl-von-Frisch-Strasse 16, 35043 Marburg, Germany.
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24
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Sagawa T, Mashiko R, Yokota Y, Naruse Y, Okada M, Kojima H. Logistic Regression of Ligands of Chemotaxis Receptors Offers Clues about Their Recognition by Bacteria. Front Bioeng Biotechnol 2018; 5:88. [PMID: 29404321 PMCID: PMC5786873 DOI: 10.3389/fbioe.2017.00088] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Accepted: 12/26/2017] [Indexed: 11/13/2022] Open
Abstract
Because of relative simplicity of signal transduction pathway, bacterial chemotaxis sensory systems have been expected to be applied to biosensor. Tar and Tsr receptors mediate chemotaxis of Escherichia coli and have been studied extensively as models of chemoreception by bacterial two-transmembrane receptors. Such studies are typically conducted using two canonical ligands: l-aspartate for Tar and l-serine for Tsr. However, Tar and Tsr also recognize various analogs of aspartate and serine; it remains unknown whether the mechanism by which the canonical ligands are recognized is also common to the analogs. Moreover, in terms of engineering, it is important to know a single species of receptor can recognize various ligands to utilize bacterial receptor as the sensor for wide range of substances. To answer these questions, we tried to extract the features that are common to the recognition of the different analogs by constructing classification models based on machine-learning. We computed 20 physicochemical parameters for each of 38 well-known attractants that act as chemoreception ligands, and 15 known non-attractants. The classification models were generated by utilizing one or more of the seven physicochemical properties as descriptors. From the classification models, we identified the most effective physicochemical parameter for classification: the minimum electron potential. This descriptor that occurred repeatedly in classification models with the highest accuracies, This descriptor used alone could accurately classify 42/53 of compounds. Among the 11 misclassified compounds, eight contained two carboxyl groups, which is analogous to the structure of characteristic of aspartate analog. When considered separately, 16 of the 17 aspartate analogs could be classified accurately based on the distance between their two carboxyl groups. As shown in these results, we succeed to predict the ligands for bacterial chemoreceptors using only a few descriptors; single descriptor for single receptor. This result might be due to the relatively simple topology of bacterial two-transmembrane receptors compared to the G-protein-coupled receptors of seven-transmembrane receptors. Moreover, this distance between carboxyl groups correlated with the receptor binding affinity of the aspartate analogs. In view of this correlation, we propose a common mechanism underlying ligand recognition by Tar of compounds with two carboxyl groups.
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Affiliation(s)
- Takashi Sagawa
- National Institute of Information and Communications Technology (NICT), Advanced ICT Research Institute, Kobe, Japan
| | - Ryota Mashiko
- National Institute of Information and Communications Technology (NICT), Advanced ICT Research Institute, Kobe, Japan.,Department of Bioengineering, Nagaoka University of Technology, Nagaoka, Japan
| | - Yusuke Yokota
- National Institute of Information and Communications Technology (NICT), Advanced ICT Research Institute, Kobe, Japan
| | - Yasushi Naruse
- National Institute of Information and Communications Technology (NICT), Advanced ICT Research Institute, Kobe, Japan
| | - Masato Okada
- National Institute of Information and Communications Technology (NICT), Advanced ICT Research Institute, Kobe, Japan.,Department of Complexity Science and Engineering, The University of Tokyo, Kashiwa, Japan
| | - Hiroaki Kojima
- National Institute of Information and Communications Technology (NICT), Advanced ICT Research Institute, Kobe, Japan
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25
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Stolze Y, Bremges A, Maus I, Pühler A, Sczyrba A, Schlüter A. Targeted in situ metatranscriptomics for selected taxa from mesophilic and thermophilic biogas plants. Microb Biotechnol 2017; 11:667-679. [PMID: 29205917 PMCID: PMC6011919 DOI: 10.1111/1751-7915.12982] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 10/23/2017] [Accepted: 10/23/2017] [Indexed: 11/26/2022] Open
Abstract
Biogas production is performed anaerobically by complex microbial communities with key species driving the process. Hence, analyses of their in situ activities are crucial to understand the process. In a previous study, metagenome sequencing and subsequent genome binning for different production‐scale biogas plants (BGPs) resulted in four genome bins of special interest, assigned to the phyla Thermotogae, Fusobacteria, Spirochaetes and Cloacimonetes, respectively, that were genetically analysed. In this study, metatranscriptome sequencing of the same BGP samples was conducted, enabling in situ transcriptional activity determination of these genome bins. For this, mapping of metatranscriptome reads on genome bin sequences was performed providing transcripts per million (TPM) values for each gene. This approach revealed an active sugar‐based metabolism of the Thermotogae and Spirochaetes bins and an active amino acid‐based metabolism of the Fusobacteria and Cloacimonetes bins. The data also hint at syntrophic associations of the four corresponding species with methanogenic Archaea.
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Affiliation(s)
- Yvonne Stolze
- Center for Biotechnology - CeBiTec, Bielefeld University, Universitätsstraße 27, 33615, Bielefeld, Germany
| | - Andreas Bremges
- Center for Biotechnology - CeBiTec, Bielefeld University, Universitätsstraße 27, 33615, Bielefeld, Germany.,Faculty of Technology, Bielefeld University, Universitätsstraße 25, 33615, Bielefeld, Germany
| | - Irena Maus
- Center for Biotechnology - CeBiTec, Bielefeld University, Universitätsstraße 27, 33615, Bielefeld, Germany
| | - Alfred Pühler
- Center for Biotechnology - CeBiTec, Bielefeld University, Universitätsstraße 27, 33615, Bielefeld, Germany
| | - Alexander Sczyrba
- Center for Biotechnology - CeBiTec, Bielefeld University, Universitätsstraße 27, 33615, Bielefeld, Germany.,Faculty of Technology, Bielefeld University, Universitätsstraße 25, 33615, Bielefeld, Germany
| | - Andreas Schlüter
- Center for Biotechnology - CeBiTec, Bielefeld University, Universitätsstraße 27, 33615, Bielefeld, Germany
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26
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Machuca MA, Johnson KS, Liu YC, Steer DL, Ottemann KM, Roujeinikova A. Helicobacter pylori chemoreceptor TlpC mediates chemotaxis to lactate. Sci Rep 2017; 7:14089. [PMID: 29075010 PMCID: PMC5658362 DOI: 10.1038/s41598-017-14372-2] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 10/06/2017] [Indexed: 12/13/2022] Open
Abstract
It is recently appreciated that many bacterial chemoreceptors have ligand-binding domains (LBD) of the dCACHE family, a structure with two PAS-like subdomains, one membrane-proximal and the other membrane-distal. Previous studies had implicated only the membrane-distal subdomain in ligand recognition. Here, we report the 2.2 Å resolution crystal structure of dCACHE LBD of the Helicobacter pylori chemoreceptor TlpC. H. pylori tlpC mutants are outcompeted by wild type during stomach colonisation, but no ligands had been mapped to this receptor. The TlpC dCACHE LBD has two PAS-like subdomains, as predicted. The membrane-distal one possesses a long groove instead of a small, well-defined pocket. The membrane-proximal subdomain, in contrast, had a well-delineated pocket with a small molecule that we identified as lactate. We confirmed that amino acid residues making contact with the ligand in the crystal structure-N213, I218 and Y285 and Y249-were required for lactate binding. We determined that lactate is an H. pylori chemoattractant that is sensed via TlpC with a K D = 155 µM. Lactate is utilised by H. pylori, and our work suggests that this pathogen seeks out lactate using chemotaxis. Furthermore, our work suggests that dCACHE domain proteins can utilise both subdomains for ligand recognition.
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Affiliation(s)
- Mayra A Machuca
- Infection and Immunity Program, Monash Biomedicine Discovery Institute, Monash University, Clayton, Victoria, 3800, Australia
- Department of Microbiology, Monash University, Clayton, Victoria, 3800, Australia
| | - Kevin S Johnson
- Department of Microbiology and Environmental Toxicology, University of California Santa Cruz, Santa Cruz, CA, 95064, USA
| | - Yu C Liu
- Department of Microbiology, Monash University, Clayton, Victoria, 3800, Australia
| | - David L Steer
- Monash Biomedical Proteomics Facility, Monash University, Clayton, Victoria, 3800, Australia
| | - Karen M Ottemann
- Department of Microbiology and Environmental Toxicology, University of California Santa Cruz, Santa Cruz, CA, 95064, USA.
| | - Anna Roujeinikova
- Infection and Immunity Program, Monash Biomedicine Discovery Institute, Monash University, Clayton, Victoria, 3800, Australia.
- Department of Microbiology, Monash University, Clayton, Victoria, 3800, Australia.
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, 3800, Australia.
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27
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Webb BA, Compton KK, Del Campo JSM, Taylor D, Sobrado P, Scharf BE. Sinorhizobium meliloti Chemotaxis to Multiple Amino Acids Is Mediated by the Chemoreceptor McpU. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2017; 30:770-777. [PMID: 28745538 DOI: 10.1094/mpmi-04-17-0096-r] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The legume symbiont Sinorhizobium meliloti is chemoattracted to compounds exuded by germinating seeds of its host alfalfa. This response is mainly mediated by the S. meliloti chemoreceptor McpU. McpU also has a prominent contribution in sensing a synthetic amino acid (aa) mixture mimicking the amounts and composition observed in seed exudate. Here, we used the hydrogel capillary assay to quantify chemotactic responses of S. meliloti to individual aa exuded by germinating alfalfa seeds and to define the role of McpU in this behavior. S. meliloti exhibited positive chemotaxis responses to all proteinogenic aa, except for aspartate, and to citrulline, cystine, gamma-aminobutyric acid, and ornithine. Wild-type responses were diverse in intensity, while a strain lacking mcpU displayed strongly diminished responses. Differential scanning fluorimetry demonstrated interaction of the purified periplasmic region of McpU (McpU-PR) with the aa, except glutamate and aspartate. We additionally tested organic acids and sugars, but there were no significant interactions with the McpU ligand-binding domain, except for citrate. Using ligand displacement, we confirmed the interaction of McpU-PR with aa representing strong and weak attractants. Our results show that S. meliloti McpU is a broad-range aa receptor mediating differential responses to individual attractants, which does not bind negatively charged aa.
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Affiliation(s)
- Benjamin A Webb
- 1 Virginia Tech, Department of Biological Sciences, Life Sciences I, Blacksburg, VA 24061, U.S.A.; and
| | - K Karl Compton
- 1 Virginia Tech, Department of Biological Sciences, Life Sciences I, Blacksburg, VA 24061, U.S.A.; and
| | | | - Doris Taylor
- 1 Virginia Tech, Department of Biological Sciences, Life Sciences I, Blacksburg, VA 24061, U.S.A.; and
| | - Pablo Sobrado
- 2 Virginia Tech, Department of Biochemistry, Fralin Life Science Institute
| | - Birgit E Scharf
- 1 Virginia Tech, Department of Biological Sciences, Life Sciences I, Blacksburg, VA 24061, U.S.A.; and
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28
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Salah Ud-Din AIM, Roujeinikova A. Methyl-accepting chemotaxis proteins: a core sensing element in prokaryotes and archaea. Cell Mol Life Sci 2017; 74:3293-3303. [PMID: 28409190 PMCID: PMC11107704 DOI: 10.1007/s00018-017-2514-0] [Citation(s) in RCA: 111] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Revised: 03/06/2017] [Accepted: 03/24/2017] [Indexed: 11/29/2022]
Abstract
Chemotaxis is the directed motility by means of which microbes sense chemical cues and relocate towards more favorable environments. Methyl-accepting chemotaxis proteins (MCPs) are the most common receptors in bacteria and archaea. They are arranged as trimers of dimers that, in turn, form hexagonal arrays in the cytoplasmic membrane or in the cytoplasm. Several different classes of MCPs have been identified according to their ligand binding region and membrane topology. MCPs have been further classified based on the length and sequence conservation of their cytoplasmic domains. Clusters of membrane-embedded MCPs often localize to the poles of the cell, whereas cytoplasmic MCPs can be targeted to the poles or distributed throughout the cell body. MCPs play an important role in cell survival, pathogenesis, and biodegradation. Bacterial adaptation to diverse environmental conditions promotes diversity among the MCPs. This review summarizes structure, classification, and structure-activity relationship of the known MCP receptors, with a brief overview of the signal transduction mechanisms in bacteria and archaea.
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Affiliation(s)
- Abu Iftiaf Md Salah Ud-Din
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, VIC, Australia
| | - Anna Roujeinikova
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, VIC, Australia.
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC, Australia.
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29
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Guo M, Huang Z, Yang J. Is there any crosstalk between the chemotaxis and virulence induction signaling in Agrobacterium tumefaciens? Biotechnol Adv 2017; 35:505-511. [PMID: 28342941 DOI: 10.1016/j.biotechadv.2017.03.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2016] [Revised: 03/17/2017] [Accepted: 03/22/2017] [Indexed: 12/25/2022]
Abstract
Agrobacterium tumefaciens, a soil-born phytopathogenic bacterium, is well known as a nature's engineer due to its ability to genetically transform the host by transferring a DNA fragment (called T-DNA) from its Ti plasmid to host-cell genome. To combat the harsh soil environment and seek the appropriate host, A. tumefaciens can sense and be attracted by a large number of chemical compounds released by wounded host. As a member of α-proteobacterium, A. tumefaciens has a chemotaxis system different from that found in Escherichia coli, since many chemoattractants for A. tumefaciens chemotaxis are virulence (vir) inducers. However, advances in the study of the chemotaxis paradigm, E. coli chemotaxis system, have provided enough information to analyze the A. tumefaciens chemotaxis. At low concentration, chemoattractants elicit A. tumefaciens chemotaxis and attract the species to the wound sites of the host. At high concentration, chemoattractants induce the expression of virulence genes and trigger T-DNA transfer. Recent studies on the VirA and ChvE of the vir-induction system provide some evidences to support the crosstalk between chemotaxis and vir-induction. This review compares the core components of chemotaxis signaling system of A. tumefaciens with those observed in other species, discusses the connection between chemotaxis and vir-induction in A. tumefaciens, and proposes a model depicting the signaling crosstalk between chemotaxis and vir-induction.
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Affiliation(s)
- Minliang Guo
- College of Bioscience and Biotechnology, Yangzhou University, Yangzhou, Jiangsu 225009, China.
| | - Zhiwei Huang
- College of Bioscience and Biotechnology, Yangzhou University, Yangzhou, Jiangsu 225009, China
| | - Jing Yang
- College of Bioscience and Biotechnology, Yangzhou University, Yangzhou, Jiangsu 225009, China
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30
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Ames P, Hunter S, Parkinson JS. Evidence for a Helix-Clutch Mechanism of Transmembrane Signaling in a Bacterial Chemoreceptor. J Mol Biol 2016; 428:3776-88. [PMID: 27019297 PMCID: PMC5023463 DOI: 10.1016/j.jmb.2016.03.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 03/14/2016] [Accepted: 03/15/2016] [Indexed: 11/19/2022]
Abstract
The Escherichia coli Tsr protein contains a periplasmic serine-binding domain that transmits ligand occupancy information to a cytoplasmic kinase-control domain to regulate the cell's flagellar motors. The Tsr input and output domains communicate through conformational changes transmitted through a transmembrane helix (TM2), a five-residue control cable helix at the membrane-cytoplasm interface, and a four-helix HAMP bundle. Changes in serine occupancy are known to promote TM2 piston displacements in one subunit of the Tsr homodimer. We explored how such piston motions might be relayed through the control cable to reach the input AS1 helix of HAMP by constructing and characterizing mutant receptors that had one-residue insertions or deletions in the TM2-control cable segment of Tsr. TM2 deletions caused kinase-off output shifts; TM2 insertions caused kinase-on shifts. In contrast, control cable deletions caused kinase-on output, whereas insertions at the TM2-control cable junction caused kinase-off output. These findings rule out direct mechanical transmission of TM2 conformational changes to HAMP. Instead, we suggest that the Tsr control cable transmits input signals to HAMP by modulating the intensity of structural clashes between out-of-register TM2 and AS1 helices. Inward displacement of TM2 might alter the sidechain environment of control cable residues at the membrane core-headgroup interface, causing a break in the control cable helix to attenuate the register mismatch and enhance HAMP packing stability, leading to a kinase-off output response. This helix-clutch model offers a new perspective on the mechanism of transmembrane signaling in chemoreceptors.
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Affiliation(s)
- Peter Ames
- Biology Department, University of Utah, Salt Lake City, Utah 84112, USA
| | - Samuel Hunter
- Biology Department, University of Utah, Salt Lake City, Utah 84112, USA
| | - John S Parkinson
- Biology Department, University of Utah, Salt Lake City, Utah 84112, USA.
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31
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Bi S, Pollard AM, Yang Y, Jin F, Sourjik V. Engineering Hybrid Chemotaxis Receptors in Bacteria. ACS Synth Biol 2016; 5:989-1001. [PMID: 27285081 DOI: 10.1021/acssynbio.6b00053] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Most bacteria use transmembrane sensors to detect a wide range of environmental stimuli. A large class of such sensors are the chemotaxis receptors used by motile bacteria to follow environmental chemical gradients. In Escherichia coli, chemotaxis receptors are known to mediate highly sensitive responses to ligands, making them potentially useful for biosensory applications. However, with only four ligand-binding chemotaxis receptors, the natural ligand spectrum of E. coli is limited. The design of novel chemoreceptors to extend the sensing capabilities of E. coli is therefore a critical aspect of chemotaxis-based biosensor development. One path for novel sensor design is to harvest the large natural diversity of chemosensory functions found in bacteria by creating hybrids that have the signaling domain from E. coli chemotaxis receptors and sensory domains from other species. In this work, we demonstrate that the E. coli receptor Tar can be successfully combined with most typical sensory domains found in chemotaxis receptors and in evolutionary-related two-component histidine kinases. We show that such functional hybrids can be generated using several different fusion points. Our work further illustrates how hybrid receptors could be used to quantitatively characterize ligand specificity of chemotaxis receptors and histidine kinases using standardized assays in E. coli.
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Affiliation(s)
- Shuangyu Bi
- Max Planck Institute for Terrestrial Microbiology & LOEWE Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Abiola M. Pollard
- Max Planck Institute for Terrestrial Microbiology & LOEWE Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Yiling Yang
- Max Planck Institute for Terrestrial Microbiology & LOEWE Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Fan Jin
- Max Planck Institute for Terrestrial Microbiology & LOEWE Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Victor Sourjik
- Max Planck Institute for Terrestrial Microbiology & LOEWE Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
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López-Farfán D, Reyes-Darias JA, Krell T. The expression of many chemoreceptor genes depends on the cognate chemoeffector as well as on the growth medium and phase. Curr Genet 2016; 63:457-470. [DOI: 10.1007/s00294-016-0646-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 08/24/2016] [Accepted: 08/31/2016] [Indexed: 01/03/2023]
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Rico-Jiménez M, Reyes-Darias JA, Ortega Á, Díez Peña AI, Morel B, Krell T. Two different mechanisms mediate chemotaxis to inorganic phosphate in Pseudomonas aeruginosa. Sci Rep 2016; 6:28967. [PMID: 27353565 PMCID: PMC4926252 DOI: 10.1038/srep28967] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 06/13/2016] [Indexed: 11/09/2022] Open
Abstract
Inorganic phosphate (Pi) is a central signaling molecule that modulates virulence in various pathogens. In Pseudomonas aeruginosa, low Pi concentrations induce transcriptional alterations that increase virulence. Also, under low Pi levels, P. aeruginosa exhibits Pi chemotaxis—a process mediated by the two non-paralogous receptors CtpH and CtpL. Here we show that the two receptors operate via different mechanisms. We demonstrate that the ligand binding domain (LBD) of CtpH but not CtpL binds Pi directly. We identify the periplasmic ligand binding protein PstS as the protein that binds in its Pi loaded state to CtpL, resulting in receptor stimulation. PstS forms part of the Pi transporter and has thus a double function in Pi transport and chemotaxis. The affinity of Pi for CtpH was modest whereas that for PstS very high, which may explain why CtpH and CtpL mediate chemotaxis to high and low Pi concentrations, respectively. The pstS/ctpH double mutant was almost devoid of Pi taxis, indicating that PstS is the only CtpL Pi-shuttle. Chemotaxis mechanisms based on indirect ligand recognition were unambiguously identified in enterobacteria. The discovery of a similar mechanism in a different bacterial order, involving a different chemoreceptor type and chemoeffector suggests that such systems are widespread.
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Affiliation(s)
- Miriam Rico-Jiménez
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Jose Antonio Reyes-Darias
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Álvaro Ortega
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Ana Isabel Díez Peña
- Department of Physical Chemistry, Faculty of Chemistry, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia, 30071 Murcia, Spain
| | - Bertrand Morel
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Tino Krell
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain
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Borrelia burgdorferi CheD Promotes Various Functions in Chemotaxis and the Pathogenic Life Cycle of the Spirochete. Infect Immun 2016; 84:1743-1752. [PMID: 27021244 DOI: 10.1128/iai.01347-15] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 03/23/2016] [Indexed: 12/13/2022] Open
Abstract
Borrelia burgdorferi possesses a sophisticated chemotaxis signaling system; however, the roles of the majority of the chemotaxis proteins in the infectious life cycle have not yet been demonstrated. Specifically, the role of CheD during host colonization has not been demonstrated in any bacterium. Here, we systematically characterized the B. burgdorferi CheD homolog using genetics and biochemical and mouse-tick-mouse infection cycle studies. Bacillus subtilis CheD plays an important role in chemotaxis by deamidation of methyl-accepting chemotaxis protein receptors (MCPs) and by increasing the receptor kinase activity or enhancing CheC phosphatase activity, thereby regulating the levels of the CheY response regulator. Our biochemical analysis indicates that B. burgdorferi CheD significantly enhances CheX phosphatase activity by specifically interacting with the phosphatase. Moreover, CheD specifically binds two of the six MCPs, indicating that CheD may also modulate the receptor proteins. Although the motility of the cheD mutant cells was indistinguishable from that of the wild-type cells, the mutant did exhibit reduced chemotaxis. Importantly, the mutant showed significantly reduced infectivity in C3H/HeN mice via needle inoculation. Mouse-tick-mouse infection assays indicated that CheD is dispensable for acquisition or transmission of spirochetes; however, the viability of cheD mutants in ticks is marginally reduced compared to that of the wild-type or complemented cheD spirochetes. These data suggest that CheD plays an important role in the chemotaxis and pathogenesis of B. burgdorferi We propose potential connections between CheD, CheX, and MCPs and discuss how these interactions play critical roles during the infectious life cycle of the spirochete.
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A Chemotaxis Receptor Modulates Nodulation during the Azorhizobium caulinodans-Sesbania rostrata Symbiosis. Appl Environ Microbiol 2016; 82:3174-84. [PMID: 26994081 DOI: 10.1128/aem.00230-16] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2016] [Accepted: 03/14/2016] [Indexed: 01/02/2023] Open
Abstract
UNLABELLED Azorhizobium caulinodans ORS571 is a free-living nitrogen-fixing bacterium which can induce nitrogen-fixing nodules both on the root and the stem of its legume host Sesbania rostrata This bacterium, which is an obligate aerobe that moves by means of a polar flagellum, possesses a single chemotaxis signal transduction pathway. The objective of this work was to examine the role that chemotaxis and aerotaxis play in the lifestyle of the bacterium in free-living and symbiotic conditions. In bacterial chemotaxis, chemoreceptors sense environmental changes and transmit this information to the chemotactic machinery to guide motile bacteria to preferred niches. Here, we characterized a chemoreceptor of A. caulinodans containing an N-terminal PAS domain, named IcpB. IcpB is a soluble heme-binding protein that localized at the cell poles. An icpB mutant strain was impaired in sensing oxygen gradients and in chemotaxis response to organic acids. Compared to the wild-type strain, the icpB mutant strain was also affected in the production of extracellular polysaccharides and impaired in flocculation. When inoculated alone, the icpB mutant induced nodules on S. rostrata, but the nodules formed were smaller and had reduced N2-fixing activity. The icpB mutant failed to nodulate its host when inoculated competitively with the wild-type strain. Together, the results identify chemotaxis and sensing of oxygen by IcpB as key regulators of the A. caulinodans-S. rostrata symbiosis. IMPORTANCE Bacterial chemotaxis has been implicated in the establishment of various plant-microbe associations, including that of rhizobial symbionts with their legume host. The exact signal(s) detected by the motile bacteria that guide them to their plant hosts remain poorly characterized. Azorhizobium caulinodans ORS571 is a diazotroph that is a motile and chemotactic rhizobial symbiont of Sesbania rostrata, where it forms nitrogen-fixing nodules on both the roots and the stems of the legume host. We identify here a chemotaxis receptor sensing oxygen in A. caulinodans that is critical for nodulation and nitrogen fixation on the stems and roots of S. rostrata These results identify oxygen sensing and chemotaxis as key regulators of the A. caulinodans-S. rostrata symbiosis.
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SOS System Induction Inhibits the Assembly of Chemoreceptor Signaling Clusters in Salmonella enterica. PLoS One 2016; 11:e0146685. [PMID: 26784887 PMCID: PMC4718596 DOI: 10.1371/journal.pone.0146685] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 12/21/2015] [Indexed: 01/08/2023] Open
Abstract
Swarming, a flagellar-driven multicellular form of motility, is associated with bacterial virulence and increased antibiotic resistance. In this work we demonstrate that activation of the SOS response reversibly inhibits swarming motility by preventing the assembly of chemoreceptor-signaling polar arrays. We also show that an increase in the concentration of the RecA protein, generated by SOS system activation, rather than another function of this genetic network impairs chemoreceptor polar cluster formation. Our data provide evidence that the molecular balance between RecA and CheW proteins is crucial to allow polar cluster formation in Salmonella enterica cells. Thus, activation of the SOS response by the presence of a DNA-injuring compound increases the RecA concentration, thereby disturbing the equilibrium between RecA and CheW and resulting in the cessation of swarming. Nevertheless, when the DNA-damage decreases and the SOS response is no longer activated, basal RecA levels and thus polar cluster assembly are reestablished. These results clearly show that bacterial populations moving over surfaces make use of specific mechanisms to avoid contact with DNA-damaging compounds.
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Micali G, Endres RG. Bacterial chemotaxis: information processing, thermodynamics, and behavior. Curr Opin Microbiol 2015; 30:8-15. [PMID: 26731482 DOI: 10.1016/j.mib.2015.12.001] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 12/01/2015] [Accepted: 12/02/2015] [Indexed: 01/05/2023]
Abstract
Escherichia coli has long been used as a model organism due to the extensive experimental characterization of its pathways and molecular components. Take chemotaxis as an example, which allows bacteria to sense and swim in response to chemicals, such as nutrients and toxins. Many of the pathway's remarkable sensing and signaling properties are now concisely summarized in terms of design (or engineering) principles. More recently, new approaches from information theory and stochastic thermodynamics have begun to address how pathways process environmental stimuli and what the limiting factors are. However, to fully capitalize on these theoretical advances, a closer connection with single-cell experiments will be required.
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Affiliation(s)
- Gabriele Micali
- Department of Life Sciences, Imperial College, London, United Kingdom; Centre for Integrative Systems Biology and Bioinformatics, Imperial College, London, United Kingdom
| | - Robert G Endres
- Department of Life Sciences, Imperial College, London, United Kingdom; Centre for Integrative Systems Biology and Bioinformatics, Imperial College, London, United Kingdom.
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Fernández M, Morel B, Corral-Lugo A, Krell T. Identification of a chemoreceptor that specifically mediates chemotaxis toward metabolizable purine derivatives. Mol Microbiol 2015; 99:34-42. [PMID: 26355499 DOI: 10.1111/mmi.13215] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/07/2015] [Indexed: 11/30/2022]
Abstract
Chemotaxis is an essential mechanism that enables bacteria to move toward favorable ecological niches. Escherichia coli, the historical model organism for studying chemotaxis, has five well-studied chemoreceptors. However, many bacteria with different lifestyle have more chemoreceptors, most of unknown function. Using a high throughput screening approach, we identified a chemoreceptor from Pseudomonas putida KT2440, named McpH, which specifically recognizes purine and its derivatives, adenine, guanine, xanthine, hypoxanthine and uric acid. The latter five compounds form part of the purine degradation pathway, permitting their use as sole nitrogen sources. Isothermal titration calorimetry studies show that these six compounds bind McpH-Ligand Binding Domain (LBD) with very similar affinity. In contrast, non-metabolizable purine derivatives (caffeine, theophylline, theobromine), nucleotides, nucleosides or pyrimidines are unable to bind McpH-LBD. Mutation of mcpH abolished chemotaxis toward the McpH ligands identified - a phenotype that is restored by complementation. This is the first report on bacterial chemotaxis to purine derivatives and McpH the first chemoreceptor described that responds exclusively to intermediates of a catabolic pathway, illustrating a clear link between metabolism and chemotaxis. The evolution of McpH may reflect a saprophytic lifestyle, which would have exposed the studied bacterium to high concentrations of purines produced by nucleic acid degradation.
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Affiliation(s)
- Matilde Fernández
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/ Prof. Albareda, 1, 18008, Granada, Spain
| | - Bertrand Morel
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/ Prof. Albareda, 1, 18008, Granada, Spain
| | - Andrés Corral-Lugo
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/ Prof. Albareda, 1, 18008, Granada, Spain
| | - Tino Krell
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/ Prof. Albareda, 1, 18008, Granada, Spain
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Early gene expression in Pseudomonas fluorescens exposed to a polymetallic solution. Cell Biol Toxicol 2015; 31:39-81. [DOI: 10.1007/s10565-015-9294-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 02/23/2015] [Indexed: 11/27/2022]
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