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The New Phytologist Sep 2023Some nucleotide-binding and leucine-rich repeat receptors (NLRs) indirectly detect pathogen effectors by monitoring their host targets. In Arabidopsis thaliana, RIN4 is...
Some nucleotide-binding and leucine-rich repeat receptors (NLRs) indirectly detect pathogen effectors by monitoring their host targets. In Arabidopsis thaliana, RIN4 is targeted by multiple sequence-unrelated effectors and activates immune responses mediated by RPM1 and RPS2. These effectors trigger cell death in Nicotiana benthamiana, but the corresponding NLRs have yet not been identified. To identify N. benthamiana NLRs (NbNLRs) that recognize Arabidopsis RIN4-targeting effectors, we conducted a rapid reverse genetic screen using an NbNLR VIGS library. We identified that the N. benthamiana homolog of Ptr1 (Pseudomonas tomato race 1) recognizes the Pseudomonas effectors AvrRpt2, AvrRpm1, and AvrB. We demonstrated that recognition of the Xanthomonas effector AvrBsT and the Pseudomonas effector HopZ5 is conferred independently by the N. benthamiana homolog of Ptr1 and ZAR1. Interestingly, the recognition of HopZ5 and AvrBsT is contributed unequally by Ptr1 and ZAR1 in N. benthamiana and Capsicum annuum. In addition, we showed that the RLCK XII family protein JIM2 is required for the NbZAR1-dependent recognition of AvrBsT and HopZ5. The recognition of sequence-unrelated effectors by NbPtr1 and NbZAR1 provides an additional example of convergently evolved effector recognition. Identification of key components involved in Ptr1 and ZAR1-mediated immunity could reveal unique mechanisms of expanded effector recognition.
Topics: Arabidopsis; Proteins; Bacteria; Carrier Proteins; Pseudomonas; Receptors, Immunologic; Bacterial Proteins; Pseudomonas syringae; Plant Diseases; Arabidopsis Proteins; Intracellular Signaling Peptides and Proteins
PubMed: 37334551
DOI: 10.1111/nph.19073 -
Nature Chemical Biology Sep 2023Pseudomonas aeruginosa is an opportunistic pathogen that causes serious illness, especially in immunocompromised individuals. P. aeruginosa forms biofilms that...
Pseudomonas aeruginosa is an opportunistic pathogen that causes serious illness, especially in immunocompromised individuals. P. aeruginosa forms biofilms that contribute to growth and persistence in a wide range of environments. Here we investigated the aminopeptidase, P. aeruginosa aminopeptidase (PaAP) from P. aeruginosa, which is highly abundant in the biofilm matrix. PaAP is associated with biofilm development and contributes to nutrient recycling. We confirmed that post-translational processing was required for activation and PaAP is a promiscuous aminopeptidase acting on unstructured regions of peptides and proteins. Crystal structures of wild-type enzymes and variants revealed the mechanism of autoinhibition, whereby the C-terminal propeptide locks the protease-associated domain and the catalytic peptidase domain into a self-inhibited conformation. Inspired by this, we designed a highly potent small cyclic-peptide inhibitor that recapitulates the deleterious phenotype observed with a PaAP deletion variant in biofilm assays and present a path toward targeting secreted proteins in a biofilm context.
Topics: Aminopeptidases; Pseudomonas aeruginosa; Peptides, Cyclic; Biofilms; Peptide Hydrolases; Bacterial Proteins
PubMed: 37386135
DOI: 10.1038/s41589-023-01373-8 -
Advanced Science (Weinheim,... Sep 2023Hyperinflammation elicited by lipopolysaccharide (LPS) that derives from multidrug-resistant Gram-negative pathogens, leads to a sharp increase in mortality globally....
Hyperinflammation elicited by lipopolysaccharide (LPS) that derives from multidrug-resistant Gram-negative pathogens, leads to a sharp increase in mortality globally. However, monotherapies aiming to neutralize LPS often fail to improve the prognosis. Here, an all-in-one drug delivery strategy equipped with bactericidal activity, LPS neutralization, and detoxification is shown to recognize, kill pathogens, and attenuate hyperinflammation by abolishing the activation of LPS-triggered acute inflammatory responses. First, bactericidal colistin results in rapid bacterial killing, and the released LPS is subsequently sequestered. The neutralized LPS is further cleared by acyloxyacyl hydrolase to remove secondary fatty chains and detoxify LPS in situ. Last, such a system shows high efficacy in two mouse infection models challenged with Pseudomonas aeruginosa. This approach integrates direct antibacterial activity with in situ LPS neutralizing and detoxifying properties, shedding light on the development of alternative interventions to treat sepsis-associated infections.
Topics: Animals; Mice; Lipopolysaccharides; Anti-Bacterial Agents; Colistin; Bacteria; Pseudomonas aeruginosa
PubMed: 37428467
DOI: 10.1002/advs.202302950 -
Current Opinion in Pulmonary Medicine May 2024Bronchiectasis is a chronic respiratory disease characterized by dilated airways, persistent sputum production and recurrent infective exacerbations. The microbiology of... (Review)
Review
PURPOSE OF REVIEW
Bronchiectasis is a chronic respiratory disease characterized by dilated airways, persistent sputum production and recurrent infective exacerbations. The microbiology of bronchiectasis includes various potentially pathogenic microorganisms including Pseudomonas aeruginosa which is commonly cultured from patients' sputum. P. aeruginosa is difficult to eradicate and frequently exhibits antimicrobial resistance. Bacteriophage therapy offers a novel and alternative method to treating bronchiectasis and can be used in conjunction with antibiotics to improve patient outcome.
RECENT FINDINGS
Thirteen case reports/series to date have successfully used phages to treat infections in bronchiectasis patients, however these studies were constrained to few patients ( n = 32) and utilized personalized phage preparations and adjunct antibiotics. In these studies, phage therapy was delivered by inhalation, intravenously or orally and was well tolerated in most patients without any unfavourable effects. Favourable clinical or microbiological outcomes were seen following phage therapy in many patients. Longitudinal patient follow-up reported regrowth of bacteria and phage neutralization in some studies. There are five randomized clinical controlled trials ongoing aiming to use phage therapy to treat P. aeruginosa associated respiratory conditions, with limited results available to date.
SUMMARY
More research, particularly robust clinical trials, into how phages can clear respiratory infections, interact with resident microbiota, and how bacteria might develop resistance will be important to establish to ensure the success of this promising therapeutic alternative.
Topics: Humans; Bacteriophages; Anti-Bacterial Agents; Bronchiectasis; Pseudomonas Infections; Respiratory System; Pseudomonas aeruginosa
PubMed: 38345396
DOI: 10.1097/MCP.0000000000001050 -
Viruses Oct 2023Half a century has passed since the discovery of Pseudomonas phage phi6, the first enveloped dsRNA bacteriophage to be isolated. It remained the sole known dsRNA phage... (Review)
Review
Half a century has passed since the discovery of Pseudomonas phage phi6, the first enveloped dsRNA bacteriophage to be isolated. It remained the sole known dsRNA phage for a quarter of a century and the only recognised member of the family until the year 2018. After the initial discovery of phi6, additional dsRNA phages have been isolated from globally distant locations and identified in metatranscriptomic datasets, suggesting that this virus type is more ubiquitous in nature than previously acknowledged. Most identified dsRNA phages infect strains and utilise either pilus or lipopolysaccharide components of the host as the primary receptor. In addition to the receptor-mediated strictly lytic lifestyle, an alternative persistent infection strategy has been described for some dsRNA phages. To date, complete genome sequences of fourteen dsRNA phage isolates are available. Despite the high sequence diversity, similar sets of genes can typically be found in the genomes of dsRNA phages, suggesting shared evolutionary trajectories. This review provides a brief overview of the recognised members of the virus family and related dsRNA phage isolates, outlines the current classification of dsRNA phages, and discusses their relationships with eukaryotic RNA viruses.
Topics: Bacteriophages; Pseudomonas Phages; Pseudomonas; Genome, Viral
PubMed: 38005832
DOI: 10.3390/v15112154 -
PLoS Pathogens Aug 2023Pseudomonas aeruginosa (P.a.) infection accounts for nearly 20% of all cases of hospital acquired pneumonia with mortality rates >30%. P.a. infection induces a robust...
Pseudomonas aeruginosa (P.a.) infection accounts for nearly 20% of all cases of hospital acquired pneumonia with mortality rates >30%. P.a. infection induces a robust inflammatory response, which ideally enhances bacterial clearance. Unfortunately, excessive inflammation can also have negative effects, and often leads to cardiac dysfunction with associated morbidity and mortality. However, it remains unclear how P.a. lung infection causes cardiac dysfunction. Using a murine pneumonia model, we found that P.a. infection of the lungs led to severe cardiac left ventricular dysfunction and electrical abnormalities. More specifically, we found that neutrophil recruitment and release of S100A8/A9 in the lungs activates the TLR4/RAGE signaling pathways, which in turn enhance systemic inflammation and subsequent cardiac dysfunction. Paradoxically, global deletion of S100A8/A9 did not improve but aggravated cardiac dysfunction and mortality likely due to uncontrolled bacterial burden in the lungs and heart. Our results indicate that P.a. infection induced release of S100A8/9 is double-edged, providing increased risk for cardiac dysfunction yet limiting P.a. growth.
Topics: Animals; Mice; Pseudomonas aeruginosa; Heart; Inflammation; Pseudomonas Infections; Lung; Heart Diseases
PubMed: 37624851
DOI: 10.1371/journal.ppat.1011573 -
Nature Protocols Sep 2023A lack of generic and effective genetic manipulation methods for Pseudomonas has restricted fundamental research and utilization of this genus for biotechnology... (Review)
Review
A lack of generic and effective genetic manipulation methods for Pseudomonas has restricted fundamental research and utilization of this genus for biotechnology applications. Phage-encoded homologous recombination (PEHR) is an efficient tool for bacterial genome engineering. This PEHR system is based on a lambda Red-like operon (BAS) from Pseudomonas aeruginosa phage Ab31 and a Rac bacteriophage RecET-like operon (Rec-TE) from P. syringae pv. syringae B728a and also contains exogenous elements, including the RecBCD inhibitor (Redγ or Pluγ) or single-stranded DNA-binding protein (SSB), that were added to enhance the PEHR recombineering efficiency. To solve the problem of false positives in Pseudomonas editing with the PEHR system, the processive enzyme Cas3 with a minimal Type I-C Cascade-based system was combined with PEHR. This protocol describes the utilization of a Pseudomonas-specific PEHR-Cas3 system that was designed to universally and proficiently modify the genomes of Pseudomonas species. The pipeline uses standardized cassettes combined with the concerted use of SacB counterselection and Cre site-specific recombinase for markerless or seamless genome modification, in association with vectors that possess the selectively replicating template R6K to minimize recombineering background. Compared with the traditional allelic exchange editing method, the PEHR-Cas3 system does not need to construct suicide plasmids carrying long homologous arms, thus simplifying the experimental procedure and shortening the traceless editing period. Compared with general editing systems based on phage recombinases, the PEHR-Cas3 system can effectively improve the screening efficiency of mutants using the cutting ability of Cas3 protein. The entire procedure requires ~12 days.
Topics: Humans; Bacteriophages; Alleles; Homologous Recombination; Pseudomonas; CRISPR-Associated Proteins
PubMed: 37626246
DOI: 10.1038/s41596-023-00856-1 -
Annals of the American Thoracic Society Feb 2024
Topics: Humans; Retrospective Studies; COVID-19; Bronchiectasis; Pseudomonas aeruginosa; Insurance
PubMed: 38299923
DOI: 10.1513/AnnalsATS.202312-1018ED -
Microbial Ecology Dec 2023Plastic waste is a global environmental burden and long-lasting plastic polymers, including ubiquitous and toxic polyurethanes (PUs), rapidly accumulate in the water...
Plastic waste is a global environmental burden and long-lasting plastic polymers, including ubiquitous and toxic polyurethanes (PUs), rapidly accumulate in the water environments. In this study, samples were collected from the three alkaline groundwater occurrences in the geotectonic regions of the Pannonian basin of northern Serbia (Torda and Slankamen Banja) and Inner Dinarides of western Serbia (Mokra Gora) with aim to isolate and identify bacteria with plastic- and lignocellulose-degrading potential, that could be applied to reduce the burden of environmental plastic pollution. The investigated occurrences belong to cold, mildly alkaline (pH: 7.6-7.9) brackish and hyperalkaline (pH: 11.5) fresh groundwaters of the SO - Na + K, Cl - Na + K and OH, Cl - Ca, Na + K genetic type. Full-length 16S rDNA sequencing, using Oxford Nanopore sequencing device, was performed with DNA extracted from colonies obtained by cultivation of all groundwater samples, as well as with DNA extracted directly from one groundwater sample. The most abundant genera belong to Pseudomonas, Acidovorax, Kocuria and Methylotenera. All screened isolates (100%) had the ability to grow on at least 3 of the tested plastic and lignocellulosic substrates, with 53.9% isolates degrading plastic substrate Impranil® DLN-SD (SD), a model compound for PUs degradation. Isolates degrading SD that were identified by partial 16S rDNA sequencing belong to the Stenotrophomonas, Pseudomonas, Paraburkholderia, Aeromonas, Vibrio and Acidovorax genera. Taking into account that plastics, including commonly produced PUs, are widespread in groundwater, identification of PUs-degrading bacteria may have potential applications in bioremediation of groundwater polluted with this polymer.
Topics: Humans; Polyurethanes; Comamonadaceae; DNA, Ribosomal; Groundwater; Pseudomonas; Suppuration
PubMed: 38153543
DOI: 10.1007/s00248-023-02338-z -
Biometals : An International Journal on... Aug 2023Iron is important for bacterial growth and survival, as it is a common co-factor in essential enzymes. Although iron is very abundant in the earth crust, its... (Review)
Review
Iron is important for bacterial growth and survival, as it is a common co-factor in essential enzymes. Although iron is very abundant in the earth crust, its bioavailability is low in most habitats because ferric iron is largely insoluble under aerobic conditions and at neutral pH. Consequently, bacteria have evolved a plethora of mechanisms to solubilize and acquire iron from environmental and host stocks. In this review, I focus on Pseudomonas spp. and first present the main iron uptake mechanisms of this taxa, which involve the direct uptake of ferrous iron via importers, the production of iron-chelating siderophores, the exploitation of siderophores produced by other microbial species, and the use of iron-chelating compounds produced by plants and animals. In the second part of this review, I elaborate on how these mechanisms affect interactions between bacteria in microbial communities, and between bacteria and their hosts. This is important because Pseudomonas spp. live in diverse communities and certain iron-uptake strategies might have evolved not only to acquire this essential nutrient, but also to gain relative advantages over competitors in the race for iron. Thus, an integrative understanding of the mechanisms of iron acquisition and the eco-evolutionary dynamics they drive at the community level might prove most useful to understand why Pseudomonas spp., in particular, and many other bacterial species, in general, have evolved such diverse iron uptake repertoires.
Topics: Animals; Siderophores; Iron; Iron Chelating Agents; Pseudomonas; Bacteria
PubMed: 36508064
DOI: 10.1007/s10534-022-00480-8