Molecular mechanisms of N-acyl homoserine lactone signals perception by plants. - Related Documents




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824101.0000Molecular mechanisms of N-acyl homoserine lactone signals perception by plants. N-acyl homoserine lactones (AHLs) belong to the class of bacterial quorum sensing signal molecules involved in distance signal transduction between Gram-negative bacteria colonizers of the rhizosphere, as well as bacteria and plants. AHLs synchronize the activity of genes from individual cells, allowing the bacterial population to act as a multicellular organism, and establish a symbiotic or antagonistic relationship with the host plant. Although the effect of AHLs on plants has been studied for more than ten years, the mechanisms of plant perception of AHL signals are not fully understood. The specificity of the reactions caused by AHL indicates the existence of appropriate mechanisms for their perception by plants. In the current review, we summarize available data on the molecular mechanisms of AHL-signal perception in plants, its effect on plant growth, development, and stress resistance. We describe the latest research demonstrating direct (on plants) and indirect (on rhizosphere microflora) effects of AHLs, as well as the prospects of using these compounds in biotechnology to increase plant resistance to biotic and abiotic stresses.202234937124
824210.9998New antibacterial targets: Regulation of quorum sensing and secretory systems in zoonotic bacteria. Quorum sensing (QS) is a communication mechanism that controls bacterial communication and can influence the transcriptional expression of multiple genes through one or more signaling molecules, thereby coordinating the population response of multiple bacterial pathogens. Secretion systems (SS) play an equally important role in bacterial information exchange, relying on the secretory systems to secrete proteins that act as virulence factors to promote adhesion to host cells. Eight highly efficient SS have been described, all of which are involved in the secretion or transfer of virulence factors, and the effector proteins they secrete play a key role in the virulence and pathogenicity of bacteria. It has been shown that many bacterial SS are directly or indirectly regulated by QS and thus influence bacterial virulence and antibiotic resistance. This review describes the relationship between QS and SS of several common zoonotic pathogenic bacteria and outlines the molecular mechanisms of how QS systems regulate SS, to provide a theoretical basis for the study of bacterial pathogenicity and the development of novel antibacterial drugs.202337343493
824020.9998β-glucan-induced disease resistance in plants: A review. Systemic acquired resistance (SAR) and induced systemic resistance (ISR) are caused by various factors, including both pathogenic and non-pathogenic ones. β-glucan primarily originates from bacteria and fungi, some species of these organisms work as biological agents in causing diseases. When β-glucan enters plants, it triggers the defense system, leading to various reactions such as the production of proteins related to pathogenicity and defense enzymes. By extracting β-glucan from disturbed microorganisms and using it as an inducing agent, plant diseases can be effectively controlled by activating the plant's defense system. β-glucan plays a crucial role during the interaction between plants and pathogens. Therefore, modeling the plant-pathogen relationship and using the molecules involved in this interaction can help in controlling plant diseases, as pathogens have genes related to resistance against pathogenicity. Thus, it is reasonable to identify and use biological induction agents at a large scale by extracting these compounds.202337742892
834330.9998Bacterial Stress Responses as Potential Targets in Overcoming Antibiotic Resistance. Bacteria can be adapted to adverse and detrimental conditions that induce general and specific responses to DNA damage as well as acid, heat, cold, starvation, oxidative, envelope, and osmotic stresses. The stress-triggered regulatory systems are involved in bacterial survival processes, such as adaptation, physiological changes, virulence potential, and antibiotic resistance. Antibiotic susceptibility to several antibiotics is reduced due to the activation of stress responses in cellular physiology by the stimulation of resistance mechanisms, the promotion of a resistant lifestyle (biofilm or persistence), and/or the induction of resistance mutations. Hence, the activation of bacterial stress responses poses a serious threat to the efficacy and clinical success of antibiotic therapy. Bacterial stress responses can be potential targets for therapeutic alternatives to antibiotics. An understanding of the regulation of stress response in association with antibiotic resistance provides useful information for the discovery of novel antimicrobial adjuvants and the development of effective therapeutic strategies to control antibiotic resistance in bacteria. Therefore, this review discusses bacterial stress responses linked to antibiotic resistance in Gram-negative bacteria and also provides information on novel therapies targeting bacterial stress responses that have been identified as potential candidates for the effective control of Gram-negative antibiotic-resistant bacteria.202235889104
916940.9998Interference of bacterial cell-to-cell communication: a new concept of antimicrobial chemotherapy breaks antibiotic resistance. Bacteria use a cell-to-cell communication activity termed "quorum sensing" to coordinate group behaviors in a cell density dependent manner. Quorum sensing influences the expression profile of diverse genes, including antibiotic tolerance and virulence determinants, via specific chemical compounds called "autoinducers". During quorum sensing, Gram-negative bacteria typically use an acylated homoserine lactone (AHL) called autoinducer 1. Since the first discovery of quorum sensing in a marine bacterium, it has been recognized that more than 100 species possess this mechanism of cell-to-cell communication. In addition to being of interest from a biological standpoint, quorum sensing is a potential target for antimicrobial chemotherapy. This unique concept of antimicrobial control relies on reducing the burden of virulence rather than killing the bacteria. It is believed that this approach will not only suppress the development of antibiotic resistance, but will also improve the treatment of refractory infections triggered by multi-drug resistant pathogens. In this paper, we review and track recent progress in studies on AHL inhibitors/modulators from a biological standpoint. It has been discovered that both natural and synthetic compounds can disrupt quorum sensing by a variety of means, such as jamming signal transduction, inhibition of signal production and break-down and trapping of signal compounds. We also focus on the regulatory elements that attenuate quorum sensing activities and discuss their unique properties. Understanding the biological roles of regulatory elements might be useful in developing inhibitor applications and understanding how quorum sensing is controlled.201323720655
828450.9998Redox signaling in human pathogens. In recent studies of human bacterial pathogens, oxidation sensing and regulation have been shown to impact very diverse pathways that extend beyond inducing antioxidant genes in the bacteria. In fact, some redox-sensitive regulatory proteins act as major regulators of bacteria's adaptability to oxidative stress, an ability that originates from immune host response as well as antibiotic stress. Such proteins play particularly important roles in pathogenic bacteria S. aureus, P. aeruginosa, and M. tuberculosis in part because reactive oxygen species and reactive nitrogen species present significant challenges for pathogens during infection. Herein, we review recent progress toward the identification and understanding of oxidation sensing and regulation in human pathogens. The newly identified redox switches in pathogens are a focus of this review. We will cover several reactive oxygen species-sensing global regulators in both gram-positive and gram-negative pathogenic bacteria in detail. The following discussion of the mechanisms that these proteins employ to sense redox signals through covalent modification of redox active amino acid residues or associated metalloprotein centers will provide further understanding of bacteria pathogenesis, antibiotic resistance, and host-pathogen interaction.201120578795
824460.9998Plant defensins: types, mechanism of action and prospects of genetic engineering for enhanced disease resistance in plants. Natural antimicrobial peptides have been shown as one of the important tools to combat certain pathogens and play important role as a part of innate immune system in plants and, also adaptive immunity in animals. Defensin is one of the antimicrobial peptides with a diverse nature of mechanism against different pathogens like viruses, bacteria and fungi. They have a broad function in humans, vertebrates, invertebrates, insects, and plants. Plant defensins primarily interact with membrane lipids for their biological activity. Several antimicrobial peptides (AMPs) have been overexpressed in plants for enhanced disease protection. The plants defensin peptides have been efficiently employed as an effective strategy for control of diseases in plants. They can be successfully integrated in plants genome along with some other peptide genes in order to produce transgenic crops for enhanced disease resistance. This review summarizes plant defensins, their expression in plants and enhanced disease resistance potential against phytopathogens.201931065492
917170.9998Small molecules modulating AHL-based quorum sensing to attenuate bacteria virulence and biofilms as promising antimicrobial drugs. Clinically significant antibiotic resistance is one of the greatest challenges of the twenty-first century. Yet new antibiotics are currently being developed at a much slower pace than our growing need for such drugs. Instead of focusing on conventional therapeutics that target in vitro bacterial viability, an alternative therapy is to target virulence factors and biofilms. Such anti-virulence strategies have attracted more and more attention recently, for it would add both supplement and diversity to our current antimicrobial library. This approach has several potential advantages including imposing less evolutionary pressure on the development of antibiotic resistance, increasing the antibacterial targets and preserving the host endogenous microbiome. Quorum sensing is an intercellular communication process in bacterial communities, which can regulate coordinated expression of virulence factors and biofilms. N-Acyl homoserine lactones (AHLs) are autoinducers generated by a variety of Gram-negative bacteria. These signals combining with their cognate LuxR-type receptors trigger the expression of virulence genes. In this critical review, we summarize various structural types of small molecules targeting AHL-based quorum sensing to attenuate bacteria virulence factors and biofilms.201424164200
828580.9998Bacterial stress response: understanding the molecular mechanics to identify possible therapeutic targets. INTRODUCTION: Bacteria are ubiquitous and many of them are pathogenic in nature. Entry of bacteria in host and its recognition by host defense system induce stress in host cells. With time, bacteria have also developed strategies including drug resistance to escape from antibacterial therapy as well as host defense mechanism. AREAS COVERED: Bacterial stress initiates and promotes adaptive immune response through several integrated mechanisms. The mechanisms of bacteria to up and down regulate different pathways involved in these responses have been discussed. The genetic expression of these pathways can be manipulated by the pharmacological interventions. Present review discusses in these contexts and explores the possibilities to overcome stress induced by bacterial pathogens and to suggest new possible therapeutic targets. EXPERT OPINION: In our opinion, there are two important fronts to regulate the bacterial stress. One is to target caspase involved in the process of transformation and translation at gene level and protein expression. Second is the identification of bacterial genes that lead to synthesis of abnormal end products supporting bacterial survival in host environment and also to surpass the host defense mechanism. Identification of such genes and their expression products could be an effective option to encounter bacterial resistance.202132811215
920490.9998Susceptibility Genes in Bacterial Diseases of Plants. Plant susceptibility (S) genes exploited by pathogenic bacteria play critical roles in disease development, collectively contributing to symptoms, pathogen proliferation, and spread. S genes may support pathogen establishment within the host, suppress host immunity, regulate host physiology or development, or function in other ways. S genes can be passive, e.g., involved in pathogen attraction or required for pathogen effector localization or activity, or active, contributing directly to symptoms or pathogen proliferation. Knowledge of S genes is important for understanding disease and other aspects of plant biology. It is also useful for disease management, as nonfunctional alleles can slow or prevent disease and, because they are often quantitative, can exert less selection on pathogens than dominant resistance genes, allowing greater durability. In this review, we discuss bacterial exploitation of S genes, S-gene functional diversity, approaches for identifying S genes, translation of S-gene knowledge for disease control, and future perspectives on this exciting area of plant pathology.202540446167
9170100.9998It is the time for quorum sensing inhibition as alternative strategy of antimicrobial therapy. Multiple drug resistance poses a significant threat to public health worldwide, with a substantial increase in morbidity and mortality rates. Consequently, searching for novel strategies to control microbial pathogenicity is necessary. With the aid of auto-inducers (AIs), quorum sensing (QS) regulates bacterial virulence factors through cell-to-cell signaling networks. AIs are small signaling molecules produced during the stationary phase. When bacterial cultures reach a certain level of growth, these molecules regulate the expression of the bound genes by acting as mirrors that reflect the inoculum density.Gram-positive bacteria use the peptide derivatives of these signaling molecules, whereas Gram-negative bacteria use the fatty acid derivatives, and the majority of bacteria can use both types to modulate the expression of the target gene. Numerous natural and synthetic QS inhibitors (QSIs) have been developed to reduce microbial pathogenesis. Applications of QSI are vital to human health, as well as fisheries and aquaculture, agriculture, and water treatment. Video Abstract.202337316831
8245110.9998Plant Elite Squad: First Defense Line and Resistance Genes - Identification, Diversity and Functional Roles. Plants exhibit sensitive mechanisms to respond to environmental stresses, presenting some specific and non-specific reactions when attacked by pathogens, including organisms from different classes and complexity, as viroids, viruses, bacteria, fungi and nematodes. A crucial step to define the fate of the plant facing an invading pathogen is the activation of a compatible Resistance (R) gene, the focus of the present review. Different aspects regarding R-genes and their products are discussed, including pathogen recognition mechanisms, signaling and effects on induced and constitutive defense processes, splicing and post transcriptional mechanisms involved. There are still countless challenges to the complete understanding of the mechanisms involving R-genes in plants, in particular those related to the interactions with other genes of the pathogen and of the host itself, their regulation, acting mechanisms at transcriptional and post-transcriptional levels, as well as the influence of other types of stress over their regulation. A magnification of knowledge is expected when considering the novel information from the omics and systems biology.201727455974
8253120.9998Strategies used by bacterial pathogens to suppress plant defenses. Plant immune systems effectively prevent infections caused by the majority of microbial pathogens that are encountered by plants. However, successful pathogens have evolved specialized strategies to suppress plant defense responses and induce disease susceptibility in otherwise resistant hosts. Recent advances reveal that phytopathogenic bacteria use type III effector proteins, toxins, and other factors to inhibit host defenses. Host processes that are targeted by bacteria include programmed cell death, cell wall-based defense, hormone signaling, the expression of defense genes, and other basal defenses. The discovery of plant defenses that are vulnerable to pathogen attack has provided new insights into mechanisms that are essential for both bacterial pathogenesis and plant disease resistance.200415231256
8246130.9998From Functional Characterization to the Application of SWEET Sugar Transporters in Plant Resistance Breeding. The occurrence of plant diseases severely affects the quality and quantity of plant production. Plants adapt to the constant invasion of pathogens and gradually form a series of defense mechanisms, such as pathogen-associated molecular pattern-triggered immunity and microbial effector-triggered immunity. Moreover, many pathogens have evolved to inhibit the immune defense system and acquire plant nutrients as a result of their coevolution with plants. The sugars will eventually be exported transporters (SWEETs) are a novel family of sugar transporters that function as uniporters. They provide a channel for pathogens, including bacteria, fungi, and viruses, to hijack sugar from the host. In this review, we summarize the functions of SWEETs in nectar secretion, grain loading, senescence, and long-distance transport. We also focus on the interaction between the SWEET genes and pathogens. In addition, we provide insight into the potential application of SWEET genes to enhance disease resistance through the use of genome editing tools. The summary and perspective of this review will deepen our understanding of the role of SWEETs during the process of pathogen infection and provide insights into resistance breeding.202235446562
8342140.9998Inflammatory immunity and bacteriological perspectives: A new direction for copper treatment of sepsis. Copper is an essential trace element for all aerobic organisms because of its unique biological functions. In recent years, researchers have discovered that copper can induce cell death through various regulatory mechanisms, thereby inducing inflammation. Efforts have also been made to alter the chemical structure of copper to achieve either anticancer or anti-inflammatory effects. The copper ion can exhibit bactericidal effects by interfering with the integrity of the cell membrane and promoting oxidative stress. Sepsis is a systemic inflammatory response caused by infection. Some studies have revealed that copper is involved in the pathophysiological process of sepsis and is closely related to its prognosis. During the infection of sepsis, the body may enhance the antimicrobial effect by increasing the release of copper. However, to avoid copper poisoning, all organisms have evolved copper resistance genes. Therefore, further analysis of the complex relationship between copper and bacteria may provide new ideas and research directions for the treatment of sepsis.202438692229
9165150.9998Regulatory Mechanisms and Physiological Impacts of Quorum Sensing in Gram-Negative Bacteria. The Quorum sensing (QS) system is a widely existing communication mechanism, which regulates bacterial community behaviors and the expression of specific genes. The most common pathogenic bacteria in clinical infections are gram-negative bacteria, and QS plays an important regulatory role in the production of virulence factors and development of antibiotic resistance. This article reviews the QS systems of gram-negative bacteria and provides an overview of how they regulate their physiological functions.202439654694
9198160.9998Recognition of bacterial avirulence proteins occurs inside the plant cell: a general phenomenon in resistance to bacterial diseases? One of the recent exciting developments in the research area of plant-microbe interactions is a breakthrough in understanding part of the initial signalling between avirulent Gram-negative bacteria and resistant plants. For resistance to occur, both interacting organisms need to express matching genes, the plant resistance gene and the bacterial avirulence gene. The biochemical function of bacterial avirulence genes and the nature of the signal molecules recognized by the plant have been a mystery for a long time. Recently, several laboratories have shown that bacterial avirulence proteins function as elicitors that are perceived within the plant cell.19979263447
9151170.9998Bacterial exo-polysaccharides in biofilms: role in antimicrobial resistance and treatments. BACKGROUND: Bacterial biofilms are aggregation or collection of different bacterial cells which are covered by self-produced extracellular matrix and are attached to a substratum. Generally, under stress or in unfavorable conditions, free planktonic bacteria transform themselves into bacterial biofilms and become sessile. MAIN BODY: Various mechanisms involving interaction between antimicrobial and biofilm matrix components, reduced growth rates, and genes conferring antibiotic resistance have been described to contribute to enhanced resistance. Quorum sensing and multi-drug resistance efflux pumps are known to regulate the internal environment within the biofilm as well as biofilm formation; they also protect cells from antibiotic attack or immune attacks. This review summarizes data supporting the importance of exopolysaccharides during biofilm formation and its role in antibiotic resistance. CONCLUSIONS: Involvement of quorum sensing and efflux pumps in antibiotic resistance in association with exopolysaccharides. Also, strategies to overcome or attack biofilms are provided.202134557983
8286180.9997RNA Modifications in Pathogenic Bacteria: Impact on Host Adaptation and Virulence. RNA modifications are involved in numerous biological processes and are present in all RNA classes. These modifications can be constitutive or modulated in response to adaptive processes. RNA modifications play multiple functions since they can impact RNA base-pairings, recognition by proteins, decoding, as well as RNA structure and stability. However, their roles in stress, environmental adaptation and during infections caused by pathogenic bacteria have just started to be appreciated. With the development of modern technologies in mass spectrometry and deep sequencing, recent examples of modifications regulating host-pathogen interactions have been demonstrated. They show how RNA modifications can regulate immune responses, antibiotic resistance, expression of virulence genes, and bacterial persistence. Here, we illustrate some of these findings, and highlight the strategies used to characterize RNA modifications, and their potential for new therapeutic applications.202134440299
8317190.9997The Quorum Sensing Auto-Inducer 2 (AI-2) Stimulates Nitrogen Fixation and Favors Ethanol Production over Biomass Accumulation in Zymomonas mobilis. Autoinducer 2 (or AI-2) is one of the molecules used by bacteria to trigger the Quorum Sensing (QS) response, which activates expression of genes involved in a series of alternative mechanisms, when cells reach high population densities (including bioluminescence, motility, biofilm formation, stress resistance, and production of public goods, or pathogenicity factors, among others). Contrary to most autoinducers, AI-2 can induce QS responses in both Gram-negative and Gram-positive bacteria, and has been suggested to constitute a trans-specific system of bacterial communication, capable of affecting even bacteria that cannot produce this autoinducer. In this work, we demonstrate that the ethanologenic Gram-negative bacterium Zymomonas mobilis (a non-AI-2 producer) responds to exogenous AI-2 by modulating expression of genes involved in mechanisms typically associated with QS in other bacteria, such as motility, DNA repair, and nitrogen fixation. Interestingly, the metabolism of AI-2-induced Z. mobilis cells seems to favor ethanol production over biomass accumulation, probably as an adaptation to the high-energy demand of N(2) fixation. This opens the possibility of employing AI-2 during the industrial production of second-generation ethanol, as a way to boost N(2) fixation by these bacteria, which could reduce costs associated with the use of nitrogen-based fertilizers, without compromising ethanol production in industrial plants.202134073173