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Nature Apr 2023Endosymbiotic bacteria have evolved intricate delivery systems that enable these organisms to interface with host biology. One example, the extracellular contractile...
Endosymbiotic bacteria have evolved intricate delivery systems that enable these organisms to interface with host biology. One example, the extracellular contractile injection systems (eCISs), are syringe-like macromolecular complexes that inject protein payloads into eukaryotic cells by driving a spike through the cellular membrane. Recently, eCISs have been found to target mouse cells, raising the possibility that these systems could be harnessed for therapeutic protein delivery. However, whether eCISs can function in human cells remains unknown, and the mechanism by which these systems recognize target cells is poorly understood. Here we show that target selection by the Photorhabdus virulence cassette (PVC)-an eCIS from the entomopathogenic bacterium Photorhabdus asymbiotica-is mediated by specific recognition of a target receptor by a distal binding element of the PVC tail fibre. Furthermore, using in silico structure-guided engineering of the tail fibre, we show that PVCs can be reprogrammed to target organisms not natively targeted by these systems-including human cells and mice-with efficiencies approaching 100%. Finally, we show that PVCs can load diverse protein payloads, including Cas9, base editors and toxins, and can functionally deliver them into human cells. Our results demonstrate that PVCs are programmable protein delivery devices with possible applications in gene therapy, cancer therapy and biocontrol.
Topics: Animals; Humans; Mice; Cell Membrane; Eukaryotic Cells; Photorhabdus; CRISPR-Associated Protein 9; Toxins, Biological; Proteins; Drug Delivery Systems; Protein Transport
PubMed: 36991127
DOI: 10.1038/s41586-023-05870-7 -
Nature Dec 2019The current need for novel antibiotics is especially acute for drug-resistant Gram-negative pathogens. These microorganisms have a highly restrictive permeability...
The current need for novel antibiotics is especially acute for drug-resistant Gram-negative pathogens. These microorganisms have a highly restrictive permeability barrier, which limits the penetration of most compounds. As a result, the last class of antibiotics that acted against Gram-negative bacteria was developed in the 1960s. We reason that useful compounds can be found in bacteria that share similar requirements for antibiotics with humans, and focus on Photorhabdus symbionts of entomopathogenic nematode microbiomes. Here we report a new antibiotic that we name darobactin, which was obtained using a screen of Photorhabdus isolates. Darobactin is coded by a silent operon with little production under laboratory conditions, and is ribosomally synthesized. Darobactin has an unusual structure with two fused rings that form post-translationally. The compound is active against important Gram-negative pathogens both in vitro and in animal models of infection. Mutants that are resistant to darobactin map to BamA, an essential chaperone and translocator that folds outer membrane proteins. Our study suggests that bacterial symbionts of animals contain antibiotics that are particularly suitable for development into therapeutics.
Topics: Animals; Anti-Bacterial Agents; Bacterial Outer Membrane Proteins; Cell Line; Disease Models, Animal; Drug Discovery; Drug Resistance, Microbial; Escherichia coli Proteins; Female; Gastrointestinal Microbiome; Gram-Negative Bacteria; Humans; Mice; Microbial Sensitivity Tests; Microbial Viability; Mutation; Nematoda; Operon; Phenylpropionates; Photorhabdus; Substrate Specificity; Symbiosis
PubMed: 31747680
DOI: 10.1038/s41586-019-1791-1 -
Cell Apr 2019Contractile injection systems (CISs) are cell-puncturing nanodevices that share ancestry with contractile tail bacteriophages. Photorhabdus virulence cassette (PVC)...
Contractile injection systems (CISs) are cell-puncturing nanodevices that share ancestry with contractile tail bacteriophages. Photorhabdus virulence cassette (PVC) represents one group of extracellular CISs that are present in both bacteria and archaea. Here, we report the cryo-EM structure of an intact PVC from P. asymbiotica. This over 10-MDa device resembles a simplified T4 phage tail, containing a hexagonal baseplate complex with six fibers and a capped 117-nanometer sheath-tube trunk. One distinct feature of the PVC is the presence of three variants for both tube and sheath proteins, indicating a functional specialization of them during evolution. The terminal hexameric cap docks onto the topmost layer of the inner tube and locks the outer sheath in pre-contraction state with six stretching arms. Our results on the PVC provide a framework for understanding the general mechanism of widespread CISs and pave the way for using them as delivery tools in biological or therapeutic applications.
Topics: Bacteriophage T4; Cell Membrane; Cryoelectron Microscopy; Models, Molecular; Photorhabdus; Protein Conformation; Type VI Secretion Systems
PubMed: 30905475
DOI: 10.1016/j.cell.2019.02.020 -
Microbiology (Reading, England) Apr 2020Different model systems have, over the years, contributed to our current understanding of the molecular mechanisms underpinning the various types of interaction between... (Review)
Review
Different model systems have, over the years, contributed to our current understanding of the molecular mechanisms underpinning the various types of interaction between bacteria and their animal hosts. The genus comprises Gram-negative insect pathogenic bacteria that are normally found as symbionts that colonize the gut of the infective juvenile stage of soil-dwelling nematodes from the family . The nematodes infect susceptible insects and release the bacteria into the insect haemolymph where the bacteria grow, resulting in the death of the insect. At this stage the nematodes feed on the bacterial biomass and, following several rounds of reproduction, the nematodes develop into infective juveniles that leave the insect cadaver in search of new hosts. Therefore has three distinct and obligate roles to play during this life-cycle: (1) must kill the insect host; (2) must be capable of supporting nematode growth and development; and (3) must be able to colonize the gut of the next generation of infective juveniles before they leave the insect cadaver. In this review I will discuss how genetic analysis has identified key genes involved in mediating, and regulating, the interaction between and each of its invertebrate hosts. These studies have resulted in the characterization of several new families of toxins and a novel inter-kingdom signalling molecule and have also uncovered an important role for phase variation in the regulation of these different roles.
Topics: Animals; Bacterial Toxins; Gastrointestinal Tract; Host Microbial Interactions; Insecta; Life Cycle Stages; Photorhabdus; Rhabditoidea; Signal Transduction; Symbiosis
PubMed: 32209172
DOI: 10.1099/mic.0.000907 -
Science Advances Apr 2022Extracellular contractile injection systems (eCISs) are widespread bacterial nanomachines that resemble T4 phage tail. As a typical eCIS, virulence cassette (PVC) was...
Extracellular contractile injection systems (eCISs) are widespread bacterial nanomachines that resemble T4 phage tail. As a typical eCIS, virulence cassette (PVC) was proposed to inject toxins into eukaryotic cells by puncturing the cell membrane from outside. This makes it an ideal tool for protein delivery in biomedical research. However, how to manipulate this nanocomplex as a molecular syringe is still undetermined. Here, we identify that one group of N-terminal signal peptide (SP) sequences are crucial for the effector loading into the inner tube of PVC complex. By application of genetic operation, cryo-electron microscopy, in vitro translocation assays, and animal experiments, we show that, under the guidance of the SP, numerous prokaryotic and eukaryotic proteins can be loaded into PVC to exert their functions across cell membranes. We therefore might customize PVC as a potent protein delivery nanosyringe for biotherapy by selecting cargo proteins in a broad spectrum, regardless of their species, sizes, and charges.
Topics: Animals; Cryoelectron Microscopy; Photorhabdus; Polyvinyl Chloride; Protein Sorting Signals; Virulence
PubMed: 35486720
DOI: 10.1126/sciadv.abm2343 -
Ecology and Evolution Feb 2024Understanding how parasites evolved is crucial to understand the host and parasite interaction. The evolution of entomopathogenesis in rhabditid nematodes has... (Review)
Review
Understanding how parasites evolved is crucial to understand the host and parasite interaction. The evolution of entomopathogenesis in rhabditid nematodes has traditionally been thought to have occurred twice within the phylum Nematoda: in Steinernematidae and Heterorhabditidae families, which are associated with the entomopathogenic bacteria and , respectively. However, nematodes from other families that are associated with entomopathogenic bacteria have not been considered to meet the criteria for "entomopathogenic nematodes." The evolution of parasitism in nematodes suggests that ecological and evolutionary properties shared by families in the order Rhabditida favor the convergent evolution of the entomopathogenic trait in lineages with diverse lifestyles, such as saprotrophs, phoretic, and necromenic nematodes. For this reason, this paper proposes expanding the term "entomopathogenic nematode" considering the diverse modes of this attribute within Rhabditida. Despite studies are required to test the authenticity of the entomopathogenic trait in the reported species, they are valuable links that represent the early stages of specialized lineages to entomopathogenic lifestyle. An ecological and evolutionary exploration of these nematodes has the potential to deepen our comprehension of the evolution of entomopathogenesis as a convergent trait spanning across the Nematoda.
PubMed: 38352205
DOI: 10.1002/ece3.10966 -
Frontiers in Microbiology 2022The importance of and symbionts to their respective and nematode hosts is that they not only contribute to their entomopathogenicity but also to their fecundity... (Review)
Review
The importance of and symbionts to their respective and nematode hosts is that they not only contribute to their entomopathogenicity but also to their fecundity through the production of small molecules. Thus, this mini-review gives a brief introductory overview of these nematophilic bacteria. Specifically, their type species, nematode hosts, and geographic region of isolations are tabulated. The use of nucleotide sequence-based techniques for their species delineation and how pangenomes can improve this are highlighted. Using the - association as an example, the bacterium-nematode lifecycle is visualized with an emphasis on the role of bacterial biomolecules. Those currently in drug development are discussed, and two potential antimalarial lead compounds are highlighted. Thus, this mini-review tabulates forty-eight significant nematophilic bacteria and visualizes the ecological importance of their biomolecules. It further discusses three of these biomolecules that are currently in drug development. Through it, one is introduced to and bacteria, their natural production of biomolecules in the nematode-bacterium lifecycle, and how these molecules are useful in developing novel therapies.
PubMed: 36187939
DOI: 10.3389/fmicb.2022.993688 -
Microbiological Research Mar 2021In last years, the main studied microbial sources of natural blue pigments have been the eukaryotic algae, Rhodophytes and Cryptophytes, and the cyanobacterium... (Review)
Review
In last years, the main studied microbial sources of natural blue pigments have been the eukaryotic algae, Rhodophytes and Cryptophytes, and the cyanobacterium Arthrospira (Spirulina) platensis, responsible for the production of phycocyanin, one of the most important blue compounds approved for food and cosmetic use. Recent research also includes the indigoidine pigment from the bacteria Erwinia, Streptomyces and Photorhabdus. Despite these advances, there are still few options of microbial blue pigments reported so far, but the interest in these products is high due to the lack of stable natural blue pigments in nature. Filamentous fungi are particularly attractive for their ability to produce pigments with a wide range of colors. Bikaverin is a red metabolite present mainly in species of the genus Fusarium. Although originally red, the biomass containing bikaverin changes its color to blue after heat treatment, through a mechanism still unknown. In addition to the special behavior of color change by thermal treatment, bikaverin has beneficial biological properties, such as antimicrobial and antiproliferative activities, which can expand its use for the pharmaceutical and medical sectors. The present review addresses the production natural blue pigments and focuses on the properties of bikaverin, which can be an important source of blue pigment with potential applications in the food industry and in other industrial sectors.
Topics: Color; Fusarium; Pigments, Biological; Xanthones
PubMed: 33302226
DOI: 10.1016/j.micres.2020.126653 -
Frontiers in Microbiology 2022Phylum Nematoda is of great economic importance. It has been a focused area for various research activities in distinct domains across the globe. Among nematodes, there... (Review)
Review
Phylum Nematoda is of great economic importance. It has been a focused area for various research activities in distinct domains across the globe. Among nematodes, there is a group called entomopathogenic nematodes, which has two families that live in symbiotic association with bacteria of genus and , respectively. With the passing years, researchers have isolated a wide array of bioactive compounds from these symbiotically associated nematodes. In this article, we are encapsulating bioactive compounds isolated from members of the family Heterorhabditidae inhabiting in its gut. Isolated bioactive compounds have shown a wide range of biological activity against deadly pathogens to both plants as well as animals. Some compounds exhibit lethal effects against fungi, bacteria, protozoan, insects, cancerous cell lines, neuroinflammation, etc., with great potency. The main aim of this article is to collect and analyze the importance of nematode and its associated bacteria, isolated secondary metabolites, and their biomedical potential, which can serve as potential leads for further drug discovery.
PubMed: 35422783
DOI: 10.3389/fmicb.2022.790339 -
3 Biotech May 2017Five bacterial strains were isolated from the hemocoel of the greater wax moth larvae (Galleria mellonella) infected with the entomopathogenic nematodes: Heterorhabditis...
Five bacterial strains were isolated from the hemocoel of the greater wax moth larvae (Galleria mellonella) infected with the entomopathogenic nematodes: Heterorhabditis bacteriophora HP88, Heterorhabditis indicus RM1 and Heterorhabditis sp (S1), Steinernema abbasi and Steinernema sp. (S II). Strains were identified as Photorhabdus luminescens HRM1, P. luminescens HS1, P. luminescens HP88, Xenorhabdus indica and X. nematophila ATTC19061 using 16S rDNA sequence analysis. To reveal the genetic diversity among these strains, three molecular markers (RAPD, ISSR and SRAP) were employed. RAPD analysis showed 73.8 and 54.5 polymorphism percentages for the Photorhabdus and Xenorhabdus strains, respectively. ISSR analysis resulted in 70.1 and 75.2 polymorphism percentages among the Photorhabdus and Xenorhabdus strains, respectively. The SRAP analysis indicated that 75.6 and 61.2% genetic polymorphism was detected among Photorhabdus and Xenorhabdus strains, respectively. The cluster analysis grouped the three Photorhabdus strains together in one cluster and the two Xenorhabdus strains together in another cluster indicating the phylogenetic relationships among them. The genotype-specific markers detected from the three molecular markers (RAPD, ISSR and SRAP) were sufficient to distinguish between the different bacterial strains tested and can be used in the future IBM program that could be built on the use of these strains.
PubMed: 28391470
DOI: 10.1007/s13205-016-0594-4