MANUKA - Word Related Documents




#
Rank
Similarity
Title + Abs.
Year
PMID
012345
500.9197GmRAR1 and GmSGT1 are required for basal, R gene-mediated and systemic acquired resistance in soybean. RAR1, SGT1, and HSP90 are important components of effector-triggered immunity (ETI) in diverse plants, where RAR1 and SGT1 are thought to serve as HSP90 co-chaperones. We show that ETI in soybean requires RAR1 and SGT1 but not HSP90. Rsv1-mediated extreme resistance to Soybean mosaic virus (SMV) and Rpg-1b-mediated resistance to Pseudomonas syringae were compromised in plants silenced for GmRAR1 and GmSGT1-2 but not GmHSP90. This suggests that RAR1- or SGT1-dependant signaling is not always associated with a dependence on HSP90. Unlike in Arabidopsis, SGT1 in soybean also mediates ETI against the bacterial pathogen P. syringae. Similar to Arabidopsis, soybean RAR1 and SGT1 proteins interact with each other and two related HSP90 proteins. Plants silenced for GmHSP90 genes or GmRAR1 exhibited altered morphology, suggesting that these proteins also contribute to developmental processes. Silencing GmRAR1 and GmSGT1-2 impaired resistance to virulent bacteria and systemic acquired resistance (SAR) in soybean as well. Because the Arabidopsis rar1 mutant also showed a defect in SAR, we conclude that RAR1 and SGT1 serve as a point of convergence for basal resistance, ETI, and SAR. We demonstrate that, although soybean defense signaling pathways recruit structurally conserved components, they have distinct requirements for specific proteins.200919061405
62010.9171Transcriptomic Responses and Survival Mechanisms of Staphylococci to the Antimicrobial Skin Lipid Sphingosine. Sphingosines are antimicrobial lipids that form part of the innate barrier to skin colonization by microbes. Sphingosine deficiencies can result in increased epithelial infections by bacteria including Staphylococcus aureus. Recent studies have focused on the potential use of sphingosine resistance or its potential mechanisms. We used RNA-Seq to identify the common d-sphingosine transcriptomic response of the transient skin colonizer S. aureus and the dominant skin coloniser S. epidermidis. A common d-sphingosine stimulon was identified that included downregulation of the SaeSR two-component system (TCS) regulon and upregulation of both the VraSR TCS and CtsR stress regulons. We show that the PstSCAB phosphate transporter, and VraSR offer intrinsic resistance to d-sphingosine. Further, we demonstrate increased sphingosine resistance in these staphylococci evolves readily through mutations in genes encoding the FarE-FarR efflux/regulator proteins. The ease of selecting mutants with resistance to sphingosine may impact upon staphylococcal colonization of skin where the lipid is present and have implications with topical therapeutic applications.202234902269
819020.9170Identification of Quorum-Sensing Inhibitors Disrupting Signaling between Rgg and Short Hydrophobic Peptides in Streptococci. Bacteria coordinate a variety of social behaviors, important for both environmental and pathogenic bacteria, through a process of intercellular chemical signaling known as quorum sensing (QS). As microbial resistance to antibiotics grows more common, a critical need has emerged to develop novel anti-infective therapies, such as an ability to attenuate bacterial pathogens by means of QS interference. Rgg quorum-sensing pathways, widespread in the phylum Firmicutes, employ cytoplasmic pheromone receptors (Rgg transcription factors) that directly bind and elicit gene expression responses to imported peptide signals. In the human-restricted pathogen Streptococcus pyogenes, the Rgg2/Rgg3 regulatory circuit controls biofilm development in response to the short hydrophobic peptides SHP2 and SHP3. Using Rgg-SHP as a model receptor-ligand target, we sought to identify chemical compounds that could specifically inhibit Rgg quorum-sensing circuits. Individual compounds from a diverse library of known drugs and drug-like molecules were screened for their ability to disrupt complexes of Rgg and FITC (fluorescein isothiocyanate)-conjugated SHP using a fluorescence polarization (FP) assay. The best hits were found to bind Rgg3 in vitro with submicromolar affinities, to specifically abolish transcription of Rgg2/3-controlled genes, and to prevent biofilm development in S. pyogenes without affecting bacterial growth. Furthermore, the top hit, cyclosporine A, as well as its nonimmunosuppressive analog, valspodar, inhibited Rgg-SHP pathways in multiple species of Streptococcus. The Rgg-FITC-peptide-based screen provides a platform to identify inhibitors specific for each Rgg type. Discovery of Rgg inhibitors constitutes a step toward the goal of manipulating bacterial behavior for purposes of improving health. IMPORTANCE: The global emergence of antibiotic-resistant bacterial infections necessitates discovery not only of new antimicrobials but also of novel drug targets. Since antibiotics restrict microbial growth, strong selective pressures to develop resistance emerge quickly in bacteria. A new strategy to fight microbial infections has been proposed, namely, development of therapies that decrease pathogenicity of invading organisms while not directly inhibiting their growth, thus decreasing selective pressure to establish resistance. One possible means to this goal is to interfere with chemical communication networks used by bacteria to coordinate group behaviors, which can include the synchronized expression of genes that lead to disease. In this study, we identified chemical compounds that disrupt communication pathways regulated by Rgg proteins in species of Streptococcus. Treatment of cultures of S. pyogenes with the inhibitors diminished the development of biofilms, demonstrating an ability to control bacterial behavior with chemicals that do not inhibit growth.201525968646
828730.9164Characterizing the Mechanism of Action of an Ancient Antimicrobial, Manuka Honey, against Pseudomonas aeruginosa Using Modern Transcriptomics. Manuka honey has broad-spectrum antimicrobial activity, and unlike traditional antibiotics, resistance to its killing effects has not been reported. However, its mechanism of action remains unclear. Here, we investigated the mechanism of action of manuka honey and its key antibacterial components using a transcriptomic approach in a model organism, Pseudomonas aeruginosa We show that no single component of honey can account for its total antimicrobial action, and that honey affects the expression of genes in the SOS response, oxidative damage, and quorum sensing. Manuka honey uniquely affects genes involved in the explosive cell lysis process and in maintaining the electron transport chain, causing protons to leak across membranes and collapsing the proton motive force, and it induces membrane depolarization and permeabilization in P. aeruginosa These data indicate that the activity of manuka honey comes from multiple mechanisms of action that do not engender bacterial resistance.IMPORTANCE The threat of antimicrobial resistance to human health has prompted interest in complex, natural products with antimicrobial activity. Honey has been an effective topical wound treatment throughout history, predominantly due to its broad-spectrum antimicrobial activity. Unlike traditional antibiotics, honey-resistant bacteria have not been reported; however, honey remains underutilized in the clinic in part due to a lack of understanding of its mechanism of action. Here, we demonstrate that honey affects multiple processes in bacteria, and this is not explained by its major antibacterial components. Honey also uniquely affects bacterial membranes, and this can be exploited for combination therapy with antibiotics that are otherwise ineffective on their own. We argue that honey should be included as part of the current array of wound treatments due to its effective antibacterial activity that does not promote resistance in bacteria.202032606022
818840.9163Biofilm in implant infections: its production and regulation. A significant proportion of medical implants become the focus of a device-related infection, difficult to eradicate because bacteria that cause these infections live in well-developed biofilms. Biofilm is a microbial derived sessile community characterized by cells that are irreversibly attached to a substratum or interface to each other, embedded in a matrix of extracellular polymeric substances that they have produced. Bacterial adherence and biofilm production proceed in two steps: first, an attachment to a surface and, second, a cell-to-cell adhesion, with pluristratification of bacteria onto the artificial surface. The first step requires the mediation of bacterial surface proteins, the cardinal of which is similar to S. aureus autolysin and is denominated AtlE. In staphylococci the matrix of extracellular polymeric substances of biofilm is a polymer of beta-1,6-linked N-acetylglucosamine (PIA), whose synthesis is mediated by the ica operon. Biofilm formation is partially controlled by quorum sensing, an interbacterial communication mechanism dependent on population density. The principal implants that can be compromised by biofilm associated infections are: central venous catheters, heart valves, ventricular assist devices, coronary stents, neurosurgical ventricular shunts, implantable neurological stimulators, arthro-prostheses, fracture-fixation devices, inflatable penile implants, breast implants, cochlear implants, intraocular lenses, dental implants. Biofilms play an important role in the spread of antibiotic resistance. Within the high dense bacterial population, efficient horizontal transfer of resistance and virulence genes takes place. In the future, treatments that inhibit the transcription of biofilm controlling genes might be a successful strategy in inhibiting these infections.A significant proportion of medical implants become the focus of a device-related infection, difficult to eradicate because bacteria that cause these infections live in well-developed biofilms. Biofilm is a microbial derived sessile community characterized by cells that are irreversibly attached to a substratum or interface to each other, embedded in a matrix of extracellular polymeric substances that they have produced. Bacterial adherence and biofilm production proceed in two steps: first, an attachment to a surface and, second, a cell-to-cell adhesion, with pluristratification of bacteria onto the artificial surface. The first step requires the mediation of bacterial surface proteins, the cardinal of which is similar to S. aureus autolysin and is denominated AtlE. In staphylococci the matrix of extracellular polymeric substances of biofilm is a polymer of beta-1,6-linked N-acetylglucosamine (PIA), whose synthesis is mediated by the ica operon. Biofilm formation is partially controlled by quorum sensing, an interbacterial communication mechanism dependent on population density. The principal implants that can be compromised by biofilm associated infections are: central venous catheters, heart valves, ventricular assist devices, coronary stents, neurosurgical ventricular shunts, implantable neurological stimulators, arthro-prostheses, fracture-fixation devices, inflatable penile implants, breast implants, cochlear implants, intra-ocular lenses, dental implants. Biofilms play an important role in the spread of antibiotic resistance. Within the high dense bacterial population, efficient horizontal transfer of resistance and virulence genes takes place. In the future, treatments that inhibit the transcription of biofilm controlling genes might be a successful strategy in inhibiting these infections.200516353112
58350.9163MarR family proteins sense sulfane sulfur in bacteria. Members of the multiple antibiotic resistance regulator (MarR) protein family are ubiquitous in bacteria and play critical roles in regulating cellular metabolism and antibiotic resistance. MarR family proteins function as repressors, and their interactions with modulators induce the expression of controlled genes. The previously characterized modulators are insufficient to explain the activities of certain MarR family proteins. However, recently, several MarR family proteins have been reported to sense sulfane sulfur, including zero-valent sulfur, persulfide (R-SSH), and polysulfide (R-SnH, n ≥ 2). Sulfane sulfur is a common cellular component in bacteria whose levels vary during bacterial growth. The changing levels of sulfane sulfur affect the expression of many MarR-controlled genes. Sulfane sulfur reacts with the cysteine thiols of MarR family proteins, causing the formation of protein thiol persulfide, disulfide bonds, and other modifications. Several MarR family proteins that respond to reactive oxygen species (ROS) also sense sulfane sulfur, as both sulfane sulfur and ROS induce the formation of disulfide bonds. This review focused on MarR family proteins that sense sulfane sulfur. However, the sensing mechanisms reviewed here may also apply to other proteins that detect sulfane sulfur, which is emerging as a modulator of gene regulation.202438948149
50460.9160Activation of Dithiolopyrrolone Antibiotics by Cellular Reductants. Dithiolopyrrolone (DTP) natural products are broad-spectrum antimicrobial and anticancer prodrugs. The DTP structure contains a unique bicyclic ene-disulfide that once reduced in the cell, chelates metal ions and disrupts metal homeostasis. In this work we investigate the intracellular activation of the DTPs and their resistance mechanisms in bacteria. We show that the prototypical DTP holomycin is reduced by several bacterial reductases and small-molecule thiols in vitro. To understand how bacteria develop resistance to the DTPs, we generate Staphylococcus aureus mutants that exhibit increased resistance to the hybrid DTP antibiotic thiomarinol. From these mutants we identify loss-of-function mutations in redox genes that are involved in DTP activation. This work advances the understanding of how DTPs are activated and informs development of bioreductive disulfide prodrugs.202539665630
58970.9153Insulin Signaling and Insulin Resistance Facilitate Trained Immunity in Macrophages Through Metabolic and Epigenetic Changes. Adaptation of the innate immune system has been recently acknowledged, explaining sustained changes of innate immune responses. Such adaptation is termed trained immunity. Trained immunity is initiated by extracellular signals that trigger a cascade of events affecting cell metabolism and mediating chromatin changes on genes that control innate immune responses. Factors demonstrated to facilitate trained immunity are pathogenic signals (fungi, bacteria, viruses) as well non-pathogenic signals such as insulin, cytokines, adipokines or hormones. These signals initiate intracellular signaling cascades that include AKT kinases and mTOR as well as histone methylases and demethylases, resulting in metabolic changes and histone modifications. In the context of insulin resistance, AKT signaling is affected resulting in sustained activation of mTORC1 and enhanced glycolysis. In macrophages elevated glycolysis readily impacts responses to pathogens (bacteria, fungi) or danger signals (TLR-driven signals of tissue damage), partly explaining insulin resistance-related pathologies. Thus, macrophages lacking insulin signaling exhibit reduced responses to pathogens and altered metabolism, suggesting that insulin resistance is a state of trained immunity. Evidence from Insulin Receptor as well as IGF1Receptor deficient macrophages support the contribution of insulin signaling in macrophage responses. In addition, clinical evidence highlights altered macrophage responses to pathogens or metabolic products in patients with systemic insulin resistance, being in concert with cell culture and animal model studies. Herein, we review the current knowledge that supports the impact of insulin signaling and other insulin resistance related signals as modulators of trained immunity.201931244863
2080.9153Paraburkholderia phytofirmans PsJN triggers local and systemic transcriptional reprogramming in Arabidopsis thaliana and increases resistance against Botrytis cinerea. Fungal pathogens are one of the main causes of yield losses in many crops, severely affecting agricultural production worldwide. Among the various approaches to alleviate this problem, beneficial microorganisms emerge as an environmentally friendly and sustainable alternative. In addition to direct biocontrol action against pathogens, certain plant growth-promoting bacteria (PGPB) enhance the plant immune defense to control diseases through induced systemic resistance (ISR). Paraburkholderia phytofirmans PsJN has been shown as an efficient biocontrol agent against diseases. However, the specific mechanisms underlying these beneficial effects at both local and systemic level remain largely unknown. In this study, we investigated the transcriptional response of Arabidopsis thaliana at above- and below-ground levels upon interaction with P. phytofirmans PsJN, and after Botrytis cinerea infection. Our data clearly support the protective effect of P. phytofirmans PsJN through ISR against B. cinerea in plants grown in both soil and hydroponic conditions. The comparative transcriptome analysis of the mRNA and miRNA sequences revealed that PsJN modulates the expression of genes involved in abiotic stress responses, microbe-plant interactions and ISR, with ethylene signaling pathway genes standing out. In roots, PsJN predominantly downregulated the expression of genes related to microbe perception, signaling and immune response, indicating that PsJN locally provoked attenuation of defense responses to facilitate and support colonization and the maintenance of mutualistic relationship. In leaves, the increased expression of defense-related genes prior to infection in combination with the protective effect of PsJN observed in later stages of infection suggests that bacterial inoculation primes plants for enhanced systemic immune response after subsequent pathogen attack.202540530279
690.9152YprA family helicases provide the missing link between diverse prokaryotic immune systems. Bacteria and archaea possess an enormous variety of antivirus immune systems that often share homologous proteins and domains, some of which contribute to diverse defense strategies. YprA family helicases are central to widespread defense systems DISARM, Dpd, and Druantia. Here, through comprehensive phylogenetic and structural prediction analysis of the YprA family, we identify several major, previously unrecognized clades, with unique signatures of domain architecture and associations with other genes. Each YprA family clade defines a distinct class of defense systems, which we denote ARMADA (disARM-related Antiviral Defense Array), BRIGADE (Base hypermodification and Restriction Involving Genes encoding ARMADA-like and Dpd-like Effectors), or TALON (TOTE-like and ARMADA-Like Operon with Nuclease). In addition to the YprA-like helicase, ARMADA systems share two more proteins with DISARM. However, ARMADA YprA homologs are most similar to those of Druantia, suggesting ARMADA is a 'missing link' connecting DISARM and Druantia. We show experimentally that ARMADA protects bacteria against a broad range of phages via a direct, non-abortive mechanism. We also discovered multiple families of satellite phage-like mobile genetic elements that often carry both ARMADA and Druantia Type III systems and show that these can provide synergistic resistance against diverse phages.202541000832
618100.9149A novel chemical inducer of Streptococcus quorum sensing acts by inhibiting the pheromone-degrading endopeptidase PepO. Bacteria produce chemical signals (pheromones) to coordinate behaviors across a population in a process termed quorum sensing (QS). QS systems comprising peptide pheromones and their corresponding Rgg receptors are widespread among Firmicutes and may be useful targets for manipulating microbial behaviors, like suppressing virulence. The Rgg2/3 QS circuit of the human pathogen Streptococcus pyogenes controls genes affecting resistance to host lysozyme in response to short hydrophobic pheromones (SHPs). Considering that artificial activation of a QS pathway may be as useful in the objective of manipulating bacteria as inhibiting it, we sought to identify small-molecule inducers of the Rgg2/3 QS system. We report the identification of a small molecule, P516-0475, that specifically induced expression of Rgg2/3-regulated genes in the presence of SHP pheromones at concentrations lower than typically required for QS induction. In searching for the mode of action of P516-0475, we discovered that an S. pyogenes mutant deficient in pepO, a neprilysin-like metalloendopeptidase that degrades SHP pheromones, was unresponsive to the compound. P516-0475 directly inhibited recombinant PepO in vitro as an uncompetitive inhibitor. We conclude that this compound induces QS by stabilizing SHP pheromones in culture. Our study indicates the usefulness of cell-based screens that modulate pathway activities to identify unanticipated therapeutic targets contributing to QS signaling.201829203527
736110.9148Resistance Is Not Futile: The Role of Quorum Sensing Plasticity in Pseudomonas aeruginosa Infections and Its Link to Intrinsic Mechanisms of Antibiotic Resistance. Bacteria use a cell-cell communication process called quorum sensing (QS) to orchestrate collective behaviors. QS relies on the group-wide detection of extracellular signal molecules called autoinducers (AI). Quorum sensing is required for virulence and biofilm formation in the human pathogen Pseudomonas aeruginosa. In P. aeruginosa, LasR and RhlR are homologous LuxR-type soluble transcription factor receptors that bind their cognate AIs and activate the expression of genes encoding functions required for virulence and biofilm formation. While some bacterial signal transduction pathways follow a linear circuit, as phosphoryl groups are passed from one carrier protein to another ultimately resulting in up- or down-regulation of target genes, the QS system in P. aeruginosa is a dense network of receptors and regulators with interconnecting regulatory systems and outputs. Once activated, it is not understood how LasR and RhlR establish their signaling hierarchy, nor is it clear how these pathway connections are regulated, resulting in chronic infection. Here, we reviewed the mechanisms of QS progression as it relates to bacterial pathogenesis and antimicrobial resistance and tolerance.202235744765
552120.9147Aurantimycin resistance genes contribute to survival of Listeria monocytogenes during life in the environment. Bacteria can cope with toxic compounds such as antibiotics by inducing genes for their detoxification. A common detoxification strategy is compound excretion by ATP-binding cassette (ABC) transporters, which are synthesized upon compound contact. We previously identified the multidrug resistance ABC transporter LieAB in Listeria monocytogenes, a Gram-positive bacterium that occurs ubiquitously in the environment, but also causes severe infections in humans upon ingestion. Expression of the lieAB genes is strongly induced in cells lacking the PadR-type transcriptional repressor LftR, but compounds leading to relief of this repression in wild-type cells were not known. Using RNA-Seq and promoter-lacZ fusions, we demonstrate highly specific repression of the lieAB and lftRS promoters through LftR. Screening of a natural compound library yielded the depsipeptide aurantimycin A - synthesized by the soil-dwelling Streptomyces aurantiacus - as the first known naturally occurring inducer of lieAB expression. Genetic and phenotypic experiments concordantly show that aurantimycin A is a substrate of the LieAB transporter and thus, lftRS and lieAB represent the first known genetic module conferring and regulating aurantimycin A resistance. Collectively, these genes may support the survival of L. monocytogenes when it comes into contact with antibiotic-producing bacteria in the soil.201930648305
9160130.9147Interference in Bacterial Quorum Sensing: A Biopharmaceutical Perspective. Numerous bacteria utilize molecular communication systems referred to as quorum sensing (QS) to synchronize the expression of certain genes regulating, among other aspects, the expression of virulence factors and the synthesis of biofilm. To achieve this process, bacteria use signaling molecules, known as autoinducers (AIs), as chemical messengers to share information. Naturally occurring strategies that interfere with bacterial signaling have been extensively studied in recent years, examining their potential to control bacteria. To interfere with QS, bacteria use quorum sensing inhibitors (QSIs) to block the action of AIs and quorum quenching (QQ) enzymes to degrade signaling molecules. Recent studies have shown that these strategies are promising routes to decrease bacterial pathogenicity and decrease biofilms, potentially enhancing bacterial susceptibility to antimicrobial agents including antibiotics and bacteriophages. The efficacy of QSIs and QQ enzymes has been demonstrated in various animal models and are now considered in the development of new medical devices against bacterial infections, including dressings, and catheters for enlarging the therapeutic arsenal against bacteria.201829563876
518140.9146Bacitracin and nisin resistance in Staphylococcus aureus: a novel pathway involving the BraS/BraR two-component system (SA2417/SA2418) and both the BraD/BraE and VraD/VraE ABC transporters. Two-component systems (TCSs) are key regulatory pathways allowing bacteria to adapt their genetic expression to environmental changes. Bacitracin, a cyclic dodecylpeptide antibiotic, binds to undecaprenyl pyrophosphate, the lipid carrier for cell wall precursors, effectively inhibiting peptidoglycan biosynthesis. We have identified a novel and previously uncharacterized TCS in the major human pathogen Staphylococcus aureus that we show to be essential for bacitracin and nisin resistance: the BraS/BraR system (Bacitracin resistance associated; SA2417/SA2418). The braRS genes are located immediately upstream from genes encoding an ABC transporter, accordingly designated BraDE. We have shown that the BraSR/BraDE module is a key bacitracin and nisin resistance determinant in S. aureus. In the presence of low antibiotic concentrations, BraSR activate transcription of two operons encoding ABC transporters: braDE and vraDE. We identified a highly conserved imperfect palindromic sequence upstream from the braDE and vraDE promoter sequences, essential for their transcriptional activation by BraSR, suggesting it is the likely BraR binding site. We demonstrated that the two ABC transporters play distinct and original roles in antibiotic resistance: BraDE is involved in bacitracin sensing and signalling through BraSR, whereas VraDE acts specifically as a detoxification module and is sufficient to confer bacitracin and nisin resistance when produced on its own. We show that these processes require functional BraD and VraD nucleotide-binding domain proteins, and that the large extracellular loop of VraE confers its specificity in bacitracin resistance. This is the first example of a TCS associated with two ABC transporters playing separate roles in signal transduction and antibiotic resistance.201121696458
622150.9145Small-Molecule Antibiotics Inhibiting tRNA-Regulated Gene Expression Is a Viable Strategy for Targeting Gram-Positive Bacteria. Bacterial infections and the rise of antibiotic resistance, especially multidrug resistance, have generated a clear need for discovery of novel therapeutics. We demonstrated that a small-molecule drug, PKZ18, targets the T-box mechanism and inhibits bacterial growth. The T-box is a structurally conserved riboswitch-like gene regulator in the 5' untranslated region (UTR) of numerous essential genes of Gram-positive bacteria. T-boxes are stabilized by cognate, unacylated tRNA ligands, allowing the formation of an antiterminator hairpin in the mRNA that enables transcription of the gene. In the absence of an unacylated cognate tRNA, transcription is halted due to the formation of a thermodynamically more stable terminator hairpin. PKZ18 targets the site of the codon-anticodon interaction of the conserved stem I and reduces T-box-controlled gene expression. Here, we show that novel analogs of PKZ18 have improved MICs, bactericidal effects against methicillin-resistant Staphylococcus aureus (MRSA), and increased efficacy in nutrient-limiting conditions. The analogs have reduced cytotoxicity against eukaryotic cells compared to PKZ18. The PKZ18 analogs acted synergistically with aminoglycosides to significantly enhance the efficacy of the analogs and aminoglycosides, further increasing their therapeutic windows. RNA sequencing showed that the analog PKZ18-22 affects expression of 8 of 12 T-box controlled genes in a statistically significant manner, but not other 5'-UTR regulated genes in MRSA. Very low levels of resistance further support the existence of multiple T-box targets for PKZ18 analogs in the cell. Together, the multiple targets, low resistance, and synergy make PKZ18 analogs promising drugs for development and future clinical applications.202033077662
8134160.9142Sweet scents from good bacteria: Case studies on bacterial volatile compounds for plant growth and immunity. Beneficial bacteria produce diverse chemical compounds that affect the behavior of other organisms including plants. Bacterial volatile compounds (BVCs) contribute to triggering plant immunity and promoting plant growth. Previous studies investigated changes in plant physiology caused by in vitro application of the identified volatile compounds or the BVC-emitting bacteria. This review collates new information on BVC-mediated plant-bacteria airborne interactions, addresses unresolved questions about the biological relevance of BVCs, and summarizes data on recently identified BVCs that improve plant growth or protection. Recent explorations of bacterial metabolic engineering to alter BVC production using heterologous or endogenous genes are introduced. Molecular genetic approaches can expand the BVC repertoire of beneficial bacteria to target additional beneficial effects, or simply boost the production level of naturally occurring BVCs. The effects of direct BVC application in soil are reviewed and evaluated for potential large-scale field and agricultural applications. Our review of recent BVC data indicates that BVCs have great potential to serve as effective biostimulants and bioprotectants even under open-field conditions.201626177913
8137170.9142Modulation of Bacterial Fitness and Virulence Through Antisense RNAs. Regulatory RNAs contribute to gene expression control in bacteria. Antisense RNAs (asRNA) are a class of regulatory RNAs that are transcribed from opposite strands of their target genes. Typically, these untranslated transcripts bind to cognate mRNAs and rapidly regulate gene expression at the post-transcriptional level. In this article, we review asRNAs that modulate bacterial fitness and increase virulence. We chose examples that underscore the variety observed in nature including, plasmid- and chromosome-encoded asRNAs, a riboswitch-regulated asRNA, and asRNAs that require other RNAs or RNA-binding proteins for stability and activity. We explore how asRNAs improve bacterial fitness and virulence by modulating plasmid acquisition and maintenance, regulating transposon mobility, increasing resistance against bacteriophages, controlling flagellar production, and regulating nutrient acquisition. We conclude with a brief discussion on how this knowledge is helping to inform current efforts to develop new therapeutics.202033747974
8161180.9139Integrative strategies against multidrug-resistant bacteria: Synthesizing novel antimicrobial frontiers for global health. Concerningly, multidrug-resistant bacteria have emerged as a prime worldwide trouble, obstructing the treatment of infectious diseases and causing doubts about the therapeutic accidentalness of presently existing drugs. Novel antimicrobial interventions deserve development as conventional antibiotics are incapable of keeping pace with bacteria evolution. Various promising approaches to combat MDR infections are discussed in this review. Antimicrobial peptides are examined for their broad-spectrum efficacy and reduced ability to develop resistance, while phage therapy may be used under extreme situations when antibiotics fail. In addition, the possibility of CRISPR-Cas systems for specifically targeting and eradicating resistance genes from bacterial populations will be explored. Nanotechnology has opened up the route to improve the delivery system of the drug itself, increasing the efficacy and specificity of antimicrobial action while protecting its host. Discovering potential antimicrobial agents is an exciting prospect through developments in synthetic biology and the rediscovery of natural product-based medicines. Moreover, host-directed therapies are now becoming popular as an adjunct to the main strategies of therapeutics without specifically targeting pathogens. Although these developments appear impressive, questions about production scaling, regulatory approvals, safety, and efficacy for clinical employment still loom large. Thus, tackling the MDR burden requires a multi-pronged plan, integrating newer treatment modalities with existing antibiotic regimens, enforcing robust stewardship initiatives, and effecting policy changes at the global level. The international health community can gird itself against the growing menace of antibiotic resistance if collaboration between interdisciplinary bodies and sustained research endeavours is encouraged. In this study, we evaluate the synergistic potential of combining various medicines in addition to summarizing recent advancements. To rethink antimicrobial stewardship in the future, we provide a multi-tiered paradigm that combines pathogen-focused and host-directed strategies.202540914328
55190.9138Effector-triggered and pathogen-associated molecular pattern-triggered immunity differentially contribute to basal resistance to Pseudomonas syringae. Pathogens induce pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) and effector-triggered immunity (ETI) in plants. PAMPs are microbial molecules recognized by host plants as nonself signals, whereas pathogen effectors are evolved to aid in parasitism but are sometimes recognized by specific intracellular resistance proteins. In the absence of detectable ETI determining classical incompatible interactions, basal resistance exists during compatible and nonhost interactions. What triggers the basal resistance has remained elusive. Here, we provide evidence that ETI contributes to basal resistance during both compatible and nonhost Arabidopsis-Pseudomonas syringae interactions. Mutations in RAR1 and NDR1, two genes required for ETI, compromise basal resistance in both compatible and nonhost interactions. Complete nonhost resistance to P. syringae pv. tabaci required a functional type III secretion system. PTI appears to play a greater role in nonhost resistance than basal resistance during compatible interactions, because abrogation of PTI compromises basal resistance during nonhost but not compatible interactions. Strikingly, simultaneous abrogation of ETI and flagellin-induced PTI rendered plants completely susceptible to the nonadapted bacterium P. syringae pv. tabaci, indicating that ETI and PTI act synergistically during nonhost resistance. Thus, both nonhost resistance and basal resistance to virulent bacteria can be unified under PTI and ETI.201020521956