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Matilla MA, Krell T. Sensing the environment by bacterial plant pathogens: What do their numerous chemoreceptors recognize? Microb Biotechnol 2024; 17:e14368. [PMID: 37929806 PMCID: PMC10832524 DOI: 10.1111/1751-7915.14368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 10/23/2023] [Accepted: 10/24/2023] [Indexed: 11/07/2023] Open
Abstract
Bacteria have evolved multiple sensing strategies to efficiently adapt to their natural hosts and environments. In the context of plant pathology, chemotaxis allows phytopathogenic bacteria to direct their movement towards hosts through the detection of a landscape of plant-derived molecules, facilitating the initiation of the infective process. The importance of chemotaxis for the lifestyle of phytopathogens is also reflected in the fact that they have, on average, twice as many chemoreceptors as bacteria that do not interact with plants. Paradoxically, the knowledge about the function of plant pathogen chemoreceptors is scarce. Notably, many of these receptors seem to be specific to plant-interacting bacteria, suggesting that they may recognize plant-specific compounds. Here, we highlight the need to advance our knowledge of phytopathogen chemoreceptor function, which may serve as a base for the development of anti-infective therapies for the control of phytopathogens.
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Affiliation(s)
- Miguel A. Matilla
- Department of Biotechnology and Environmental ProtectionEstación Experimental del Zaidín, Consejo Superior de Investigaciones CientíficasGranadaSpain
| | - Tino Krell
- Department of Biotechnology and Environmental ProtectionEstación Experimental del Zaidín, Consejo Superior de Investigaciones CientíficasGranadaSpain
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Matilla MA, Monteagudo-Cascales E, Krell T. Advances in the identification of signals and novel sensing mechanisms for signal transduction systems. Environ Microbiol 2023; 25:79-86. [PMID: 35896893 DOI: 10.1111/1462-2920.16142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 07/16/2022] [Indexed: 01/21/2023]
Affiliation(s)
- Miguel A Matilla
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Elizabet Monteagudo-Cascales
- 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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Boyeldieu A, Poli J, Ali Chaouche A, Fierobe H, Giudici‐Orticoni M, Méjean V, Jourlin‐Castelli C. Multiple detection of both attractants and repellents by the dCache-chemoreceptor SO_1056 of Shewanella oneidensis. FEBS J 2022; 289:6752-6766. [PMID: 35668695 PMCID: PMC9796306 DOI: 10.1111/febs.16548] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Revised: 05/17/2022] [Accepted: 06/06/2022] [Indexed: 01/01/2023]
Abstract
Chemoreceptors are usually transmembrane proteins dedicated to the detection of compound gradients or signals in the surroundings of a bacterium. After detection, they modulate the activation of CheA-CheY, the core of the chemotactic pathway, to allow cells to move upwards or downwards depending on whether the signal is an attractant or a repellent, respectively. Environmental bacteria such as Shewanella oneidensis harbour dozens of chemoreceptors or MCPs (methyl-accepting chemotaxis proteins). A recent study revealed that MCP SO_1056 of S. oneidensis binds chromate. Here, we show that this MCP also detects an additional attractant (l-malate) and two repellents (nickel and cobalt). The experiments were performed in vivo by the agarose-in-plug technique after overproducing MCP SO_1056 and in vitro, when possible, by submitting the purified ligand-binding domain (LBD) of SO_1056 to a thermal shift assay (TSA) coupled to isothermal titration calorimetry (ITC). ITC assays revealed a KD of 3.4 μm for l-malate and of 47.7 μm for nickel. We conclude that MCP SO_1056 binds attractants and repellents of unrelated composition. The LBD of SO_1056 belongs to the double Cache_1 family and is highly homologous to PctA, a chemoreceptor from Pseudomonas aeruginosa that detects several amino acids. Therefore, LBDs of the same family can bind diverse compounds, confirming that experimental approaches are required to define accurate LBD-binding molecules or signals.
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Affiliation(s)
- Anne Boyeldieu
- Laboratoire de Bioénergétique et Ingénierie des Protéines (BIP, UMR7281), Centre National de la Recherche Scientifique, Institut de Microbiologie de la Méditerranée (IMM), Institut Microbiologie, Bioénergies et Biotechnologie (IM2B)Aix Marseille UniversitéFrance,Present address:
Laboratoire de Microbiologie et de Génétique Moléculaires, UMR5100, Centre de Biologie Intégrative (CBI), Centre National de la Recherche Scientifique (CNRS)Université de Toulouse, UPSFrance
| | - Jean‐Pierre Poli
- Laboratoire de Bioénergétique et Ingénierie des Protéines (BIP, UMR7281), Centre National de la Recherche Scientifique, Institut de Microbiologie de la Méditerranée (IMM), Institut Microbiologie, Bioénergies et Biotechnologie (IM2B)Aix Marseille UniversitéFrance,Université de Corse Pasquale PaoliCorteFrance
| | - Amine Ali Chaouche
- Laboratoire de Bioénergétique et Ingénierie des Protéines (BIP, UMR7281), Centre National de la Recherche Scientifique, Institut de Microbiologie de la Méditerranée (IMM), Institut Microbiologie, Bioénergies et Biotechnologie (IM2B)Aix Marseille UniversitéFrance
| | - Henri‐Pierre Fierobe
- Laboratoire de Chimie Bactérienne (LCB, UMR7283), Centre National de la Recherche Scientifique, Institut de Microbiologie de la Méditerranée (IMM), Institut Microbiologie, Bioénergies et Biotechnologie (IM2B)Aix Marseille UniversitéFrance
| | - Marie‐Thérèse Giudici‐Orticoni
- Laboratoire de Bioénergétique et Ingénierie des Protéines (BIP, UMR7281), Centre National de la Recherche Scientifique, Institut de Microbiologie de la Méditerranée (IMM), Institut Microbiologie, Bioénergies et Biotechnologie (IM2B)Aix Marseille UniversitéFrance
| | - Vincent Méjean
- Laboratoire de Bioénergétique et Ingénierie des Protéines (BIP, UMR7281), Centre National de la Recherche Scientifique, Institut de Microbiologie de la Méditerranée (IMM), Institut Microbiologie, Bioénergies et Biotechnologie (IM2B)Aix Marseille UniversitéFrance
| | - Cécile Jourlin‐Castelli
- Laboratoire de Bioénergétique et Ingénierie des Protéines (BIP, UMR7281), Centre National de la Recherche Scientifique, Institut de Microbiologie de la Méditerranée (IMM), Institut Microbiologie, Bioénergies et Biotechnologie (IM2B)Aix Marseille UniversitéFrance
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Abstract
Cyclic diguanylate (c-di-GMP) signal transduction systems provide bacteria with the ability to sense changing cell status or environmental conditions and then execute suitable physiological and social behaviors in response. In this review, we provide a comprehensive census of the stimuli and receptors that are linked to the modulation of intracellular c-di-GMP. Emerging evidence indicates that c-di-GMP networks sense light, surfaces, energy, redox potential, respiratory electron acceptors, temperature, and structurally diverse biotic and abiotic chemicals. Bioinformatic analysis of sensory domains in diguanylate cyclases and c-di-GMP-specific phosphodiesterases as well as the receptor complexes associated with them reveals that these functions are linked to a diverse repertoire of protein domain families. We describe the principles of stimulus perception learned from studying these modular sensory devices, illustrate how they are assembled in varied combinations with output domains, and summarize a system for classifying these sensor proteins based on their complexity. Biological information processing via c-di-GMP signal transduction not only is fundamental to bacterial survival in dynamic environments but also is being used to engineer gene expression circuitry and synthetic proteins with à la carte biochemical functionalities.
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Pseudomonas aeruginosa as a Model To Study Chemosensory Pathway Signaling. Microbiol Mol Biol Rev 2021; 85:85/1/e00151-20. [PMID: 33441490 DOI: 10.1128/mmbr.00151-20] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Bacteria have evolved a variety of signal transduction mechanisms that generate different outputs in response to external stimuli. Chemosensory pathways are widespread in bacteria and are among the most complex signaling mechanisms, requiring the participation of at least six proteins. These pathways mediate flagellar chemotaxis, in addition to controlling alternative functions such as second messenger levels or twitching motility. The human pathogen Pseudomonas aeruginosa has four different chemosensory pathways that carry out different functions and are stimulated by signal binding to 26 chemoreceptors. Recent research employing a diverse range of experimental approaches has advanced enormously our knowledge on these four pathways, establishing P. aeruginosa as a primary model organism in this field. In the first part of this article, we review data on the function and physiological relevance of chemosensory pathways as well as their involvement in virulence, whereas the different transcriptional and posttranscriptional regulatory mechanisms that govern pathway function are summarized in the second part. The information presented will be of help to advance the understanding of pathway function in other organisms.
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Abstract
Ethanol is a chemoattractant for Bacillus subtilis even though it is not metabolized and inhibits growth. B. subtilis likely uses ethanol to find ethanol-fermenting microorganisms to utilize as prey. Two chemoreceptors sense ethanol: HemAT and McpB. HemAT’s myoglobin-like sensing domain directly binds ethanol, but the heme group is not involved. McpB is a transmembrane receptor consisting of an extracellular sensing domain and a cytoplasmic signaling domain. While most attractants bind the extracellular sensing domain, we found that ethanol directly binds between intermonomer helices of the cytoplasmic signaling domain of McpB, using a mechanism akin to those identified in many mammalian ethanol-binding proteins. Our results indicate that the sensory repertoire of chemoreceptors extends beyond the sensing domain and can directly involve the signaling domain. Motile bacteria sense chemical gradients using chemoreceptors, which consist of distinct sensing and signaling domains. The general model is that the sensing domain binds the chemical and the signaling domain induces the tactic response. Here, we investigated the unconventional sensing mechanism for ethanol taxis in Bacillus subtilis. Ethanol and other short-chain alcohols are attractants for B. subtilis. Two chemoreceptors, McpB and HemAT, sense these alcohols. In the case of McpB, the signaling domain directly binds ethanol. We were further able to identify a single amino acid residue, Ala431, on the cytoplasmic signaling domain of McpB that, when mutated to serine, reduces taxis to alcohols. Molecular dynamics simulations suggest that the conversion of Ala431 to serine increases coiled-coil packing within the signaling domain, thereby reducing the ability of ethanol to bind between the helices of the signaling domain. In the case of HemAT, the myoglobin-like sensing domain binds ethanol, likely between the helices encapsulating the heme group. Aside from being sensed by an unconventional mechanism, ethanol also differs from many other chemoattractants because it is not metabolized by B. subtilis and is toxic. We propose that B. subtilis uses ethanol and other short-chain alcohols to locate prey, namely, alcohol-producing microorganisms.
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Chemotaxis of Pseudomonas putida F1 to Alcohols Is Mediated by the Carboxylic Acid Receptor McfP. Appl Environ Microbiol 2019; 85:AEM.01625-19. [PMID: 31471307 DOI: 10.1128/aem.01625-19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Accepted: 08/29/2019] [Indexed: 01/08/2023] Open
Abstract
Although alcohols are toxic to many microorganisms, they are good carbon and energy sources for some bacteria, including many pseudomonads. However, most studies that have examined chemosensory responses to alcohols have reported that alcohols are sensed as repellents, which is consistent with their toxic properties. In this study, we examined the chemotaxis of Pseudomonas putida strain F1 to n-alcohols with chain lengths of 1 to 12 carbons. P. putida F1 was attracted to all n-alcohols that served as growth substrates (C2 to C12) for the strain, and the responses were induced when cells were grown in the presence of alcohols. By assaying mutant strains lacking single or multiple methyl-accepting chemotaxis proteins, the receptor mediating the response to C2 to C12 alcohols was identified as McfP, the ortholog of the P. putida strain KT2440 receptor for C2 and C3 carboxylic acids. Besides being a requirement for the response to n-alcohols, McfP was required for the response of P. putida F1 to pyruvate, l-lactate, acetate, and propionate, which are detected by the KT2440 receptor, and the medium- and long-chain carboxylic acids hexanoic acid and dodecanoic acid. β-Galactosidase assays of P. putida F1 carrying an mcfP-lacZ transcriptional fusion showed that the mcfP gene is not induced in response to alcohols. Together, our results are consistent with the idea that the carboxylic acids generated from the oxidation of alcohols are the actual attractants sensed by McfP in P. putida F1, rather than the alcohols themselves.IMPORTANCE Alcohols, released as fermentation products and produced as intermediates in the catabolism of many organic compounds, including hydrocarbons and fatty acids, are common components of the microbial food web in soil and sediments. Although they serve as good carbon and energy sources for many soil bacteria, alcohols have primarily been reported to be repellents rather than attractants for motile bacteria. Little is known about how alcohols are sensed by microbes in the environment. We report here that catabolizable n-alcohols with linear chains of up to 12 carbons serve as attractants for the soil bacterium Pseudomonas putida, and rather than being detected directly, alcohols appear to be catabolized to acetate, which is then sensed by a specific cell-surface chemoreceptor protein.
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Hida A, Tajima T, Kato J. Two citrate chemoreceptors involved in chemotaxis to citrate and/or citrate-metal complexes in Ralstonia pseudosolanacearum. J Biosci Bioeng 2018; 127:169-175. [PMID: 30082220 DOI: 10.1016/j.jbiosc.2018.07.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 07/13/2018] [Accepted: 07/17/2018] [Indexed: 10/28/2022]
Abstract
The bacterial wilt pathogen Ralstonia pseudosolanacearum Ps29 exhibited chemotactic responses to citrate. This pathogen expresses 22 putative chemoreceptors. In screening a complete collection of mcp single-gene deletion mutants of Ps29, none showed a significant decrease in response to citrate compared with the wild-type strain. Analysis of a collection of stepwise- and multiple-deletion mutants of Ps29 revealed that the RS_RS07350 homolog (designated McpC) and McpP (chemoreceptor mediating both positive chemotaxis to phosphate and negative chemotaxis to maleate) are chemoreceptors for citrate. Double deletion of mcpC and mcpP markedly reduced the response to citrate, indicating that McpC and McpP are major chemoreceptors for citrate. Wild-type Ps29 was attracted to both free citrate and citrate complexed with divalent metal cations such as magnesium and calcium. The mcpC mcpP double-deletion mutant also showed significant reduction in chemotaxis to Mg2+- and Ca2+-citrate complexes. Introduction of a plasmid harboring the mcpC gene (but not the mcpP gene) restored the ability to respond to these citrate-metal complexes, demonstrating that McpC can sense complexes of citrate and metal ions such as Mg2+ and Ca2+ as well as free citrate. Thus, R. pseudosolanacearum Ps29 expresses two chemoreceptors for citrate. In plant infection assays using tomato seedlings, the mcpC and mcpP single- and double-deletion mutants of the highly virulent R. pseudosolanacearum MAFF106611 strain were as infectious as the wild-type strain, suggesting that citrate chemotaxis does not play an important role in infection of tomato plants in this assay system.
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Affiliation(s)
- Akiko Hida
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan.
| | - Takahisa Tajima
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan
| | - Junichi Kato
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan
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