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Science (New York, N.Y.) Jan 2022Gasdermin proteins form large membrane pores in human cells that release immune cytokines and induce lytic cell death. Gasdermin pore formation is triggered by...
Gasdermin proteins form large membrane pores in human cells that release immune cytokines and induce lytic cell death. Gasdermin pore formation is triggered by caspase-mediated cleavage during inflammasome signaling and is critical for defense against pathogens and cancer. We discovered gasdermin homologs encoded in bacteria that defended against phages and executed cell death. Structures of bacterial gasdermins revealed a conserved pore-forming domain that was stabilized in the inactive state with a buried lipid modification. Bacterial gasdermins were activated by dedicated caspase-like proteases that catalyzed site-specific cleavage and the removal of an inhibitory C-terminal peptide. Release of autoinhibition induced the assembly of large and heterogeneous pores that disrupted membrane integrity. Thus, pyroptosis is an ancient form of regulated cell death shared between bacteria and animals.
Topics: Apoptosis Regulatory Proteins; Bacteria; Bacterial Proteins; Bacteriophages; Bradyrhizobium; Cell Membrane; Crystallography, X-Ray; Cytophagaceae; Models, Molecular; Myxococcales; Peptide Fragments; Peptide Hydrolases; Protein Conformation; Protein Conformation, alpha-Helical; Protein Domains; Pyroptosis
PubMed: 35025633
DOI: 10.1126/science.abj8432 -
Disease Markers 2022To systematically evaluate the differences in intestinal flora before and after menopause. To provide a possible mechanism for perimenopausal syndrome and provide a... (Meta-Analysis)
Meta-Analysis Review
OBJECTIVE
To systematically evaluate the differences in intestinal flora before and after menopause. To provide a possible mechanism for perimenopausal syndrome and provide a basis for probiotics as adjuvant therapy.
METHODS
MEDLINE, EMBASE, Web of Science, Cochrane Central Register of Controlled Trials (CENTRAL), CNKI, Wanfang, and VIP databases were searched. The included studies were case-control studies.
RESULTS
Three case-control studies were included, with a total of 156 people. At the phylum level, there were no differences between premenopausal and postmenopausal women. At the genus level, the relative abundances of A. odoratum and B. cholerae were higher in postmenopausal women than in premenopausal women, with no differences among other genera. The Shannon diversity index increased after menopause, but no differences were found. Only one study found a positive association of estradiol with Gammaproteobacteria and Myxococcales and a negative association with Prevotellaceae.
CONCLUSIONS
On the basis of previous studies, it was found that there was no significant difference at the phylum level between postmenopausal women and premenopausal women, but Odoribacter and Bilophila increased at the genus level in postmenopausal women. The class of Gammaproteobacteria may be positively correlated with estradiol. Limited by the number of included studies, more high-quality clinical studies are needed for validation.
Topics: Estradiol; Female; Gastrointestinal Microbiome; Humans; Menopause; Postmenopause; Premenopause
PubMed: 35923245
DOI: 10.1155/2022/3767373 -
Microbial Physiology 2021Predatory bacteria gained interest in the last 20 years. Nevertheless, only a few species are well characterized. The endobiotic predator Bdellovibrio bacteriovorus... (Review)
Review
Predatory bacteria gained interest in the last 20 years. Nevertheless, only a few species are well characterized. The endobiotic predator Bdellovibrio bacteriovorus invades its prey to consume it from the inside, whereas Myxococcus xanthus hunts as a whole group to overcome its prey. Both species were described to prey on cyanobacteria as well. This minireview summarizes the findings of the last 20 years of predatory bacteria of cyanobacteria and is supplemented by new findings from a screening experiment for bacterial predators of the model organism Anabaena variabilis PCC 7937. Known predatory bacteria of cyanobacteria belong to the phyla Proteobacteria, Bacteroidetes, and Firmicutes and follow different hunting strategies. The underlying mechanisms are in most cases not known in much detail. Isolates from the screening experiment were clustered after predation behaviour and analyzed with respect to their size. The effect of predation in high nitrate levels and the occurrence of nitrogen-fixing cells, called heterocysts, are addressed.
Topics: Animals; Bdellovibrio bacteriovorus; Cyanobacteria; Myxococcus xanthus; Predatory Behavior
PubMed: 34010833
DOI: 10.1159/000516427 -
Current Opinion in Cell Biology Jun 2022Bacterial cells are spatiotemporally highly organised with proteins localising dynamically to distinct subcellular regions. Motility in the rod-shaped Myxococcus xanthus... (Review)
Review
Bacterial cells are spatiotemporally highly organised with proteins localising dynamically to distinct subcellular regions. Motility in the rod-shaped Myxococcus xanthus cells represents an example of signal-induced spatiotemporal regulation of cell polarity. M. xanthus cells move across surfaces with defined front-rear polarity; occasionally, they invert polarity and, in parallel, reverse direction of movement. The polarity module establishes front-rear polarity between reversals and consists of the Ras-like GTPase MglA and its cognate GEF and GAP, that all localise asymmetrically to the cell poles. The Frz chemosensory system constitutes the polarity inversion module and interfaces with the proteins of the polarity module, thereby triggering their polar repositioning. As a result, the polarity proteins, over time, toggle between the cell poles causing cells to oscillate irregularly. Here, we review recent progress in how front-rear polarity is established by the polarity module and inverted by the Frz system and highlight open questions for future studies.
Topics: Bacterial Proteins; Cell Polarity; GTP Phosphohydrolases; Myxococcus xanthus
PubMed: 35367928
DOI: 10.1016/j.ceb.2022.102076 -
Environmental Microbiology Apr 2022Light-induced carotenogenesis in Myxococcus xanthus is controlled by the B -based CarH repressor and photoreceptor, and by a separate intricate pathway involving singlet...
Light-induced carotenogenesis in Myxococcus xanthus is controlled by the B -based CarH repressor and photoreceptor, and by a separate intricate pathway involving singlet oxygen, the B -independent CarH paralogue CarA and various other proteins, some eukaryotic-like. Whether other myxobacteria conserve these pathways and undergo photoregulated carotenogenesis is unknown. Here, comparative analyses across 27 Myxococcales genomes identified carotenogenic genes, albeit arranged differently, with carH often in their genomic vicinity, in all three Myxococcales suborders. However, CarA and its associated factors were found exclusively in suborder Cystobacterineae, with carA-carH invariably in tandem in a syntenic carotenogenic operon, except for Cystobacter/Melittangium, which lack CarA but retain all other factors. We experimentally show B -mediated photoregulated carotenogenesis in representative myxobacteria, and a remarkably plastic CarH operator design and DNA binding across Myxococcales. Unlike the two characterized CarH from other phyla, which are tetrameric, Cystobacter CarH (the first myxobacterial homologue amenable to analysis in vitro) is a dimer that combines direct CarH-like B -based photoregulation with CarA-like DNA binding and inhibition by an antirepressor. This study provides new molecular insights into B -dependent photoreceptors. It further establishes the B -dependent pathway for photoregulated carotenogenesis as broadly prevalent across myxobacteria and its evolution, exclusively in one suborder, into a parallel complex B -independent circuit.
Topics: Bacterial Proteins; DNA; Gene Expression Regulation, Bacterial; Myxococcales; Phosphothreonine; Repressor Proteins
PubMed: 35005822
DOI: 10.1111/1462-2920.15895 -
Microbiology (Reading, England) Jul 2023Myxobacteria are social microbial predators that use cell-cell contacts to identify bacterial or fungal prey and to differentiate kin relatives to initiate cellular... (Review)
Review
Myxobacteria are social microbial predators that use cell-cell contacts to identify bacterial or fungal prey and to differentiate kin relatives to initiate cellular responses. For prey killing, they assemble Tad-like and type III-like secretion systems at contact sites. For kin discrimination (KD), they assemble outer membrane exchange complexes composed of the TraA and TraB receptors at contacts sites. A type VI secretion system and Rhs proteins also mediate KD. Following cellular recognition, these systems deliver appropriate effectors into target cells. For prey, this leads to cell death and lysis for nutrient consumption by myxobacteria. In KD, a panel of effectors are delivered, and if adjacent cells are clonal cells, resistance ensues because they express a cognate panel of immunity factors; while nonkin lack complete immunity and are intoxicated. This review compares and contrasts recent findings from these systems in myxobacteria.
Topics: Animals; Myxococcales; Predatory Behavior; Myxococcus xanthus; Bacterial Proteins
PubMed: 37494115
DOI: 10.1099/mic.0.001372 -
Applied and Environmental Microbiology Aug 2020Biological nitrogen fixation is an essential reaction in a major pathway for supplying nitrogen to terrestrial environments. Previous culture-independent analyses based...
Biological nitrogen fixation is an essential reaction in a major pathway for supplying nitrogen to terrestrial environments. Previous culture-independent analyses based on soil DNA/RNA/protein sequencing could globally detect the nitrogenase genes/proteins of (in the class ), commonly distributed in soil environments and predominant in paddy soils; this suggests the importance of in nitrogen fixation in soil environments. However, direct experimental evidence is lacking; there has been no research on the genetic background and ability of to fix nitrogen. Therefore, we verified the diazotrophy of based on both genomic and culture-dependent analyses using sp. strains PSR-1 and Red267 isolated from soils. Based on the comparison of gene clusters, strains PSR-1 and Red267 as well as strains Fw109-5, K, and diazotrophic and in the class contain the minimum set of genes for nitrogenase (). These results imply that species have the ability to fix nitrogen. In fact, PSR-1 and Red267 exhibited N-dependent growth and acetylene reduction activity (ARA) Transcriptional activity of the gene was also detected when both strains were cultured with N gas as a sole nitrogen source, indicating that can fix and assimilate N gas by nitrogenase. In addition, PSR-1- or Red267-inoculated soil showed ARA activity and the growth of the inoculated strains on the basis of RNA-based analysis, demonstrating that can fix nitrogen in the paddy soil environment. Our study provides novel insights into the pivotal environmental function, i.e., nitrogen fixation, of , which is a common soil bacterium. is globally distributed in soil environments, especially predominant in paddy soils. Current studies based on environmental DNA/RNA analyses frequently detect gene fragments encoding nitrogenase of from various soil environments. Although the importance of as a diazotroph in nature has been suggested by culture-independent studies, there has been no solid evidence and validation from genomic and culture-based analyses that fixes nitrogen. This study demonstrates that harboring nitrogenase genes exhibits diazotrophic ability; moreover, N-dependent growth was demonstrated and in the soil environment. Our findings indicate that nitrogen fixation is important for to survive under nitrogen-deficient environments and provide a novel insight into the environmental function of , which is a common bacterium in soils.
Topics: Myxococcales; Nitrogen Cycle; Nitrogen Fixation; Soil Microbiology
PubMed: 32532868
DOI: 10.1128/AEM.00956-20 -
Genes Mar 2023Social diversification in microbes is an evolutionary process where lineages bifurcate into distinct populations that cooperate with themselves but not with other... (Review)
Review
Social diversification in microbes is an evolutionary process where lineages bifurcate into distinct populations that cooperate with themselves but not with other groups. In bacteria, this is frequently driven by horizontal transfer of mobile genetic elements (MGEs). Here, the resulting acquisition of new genes changes the recipient's social traits and consequently how they interact with kin. These changes include discriminating behaviors mediated by newly acquired effectors. Since the producing cell is protected by cognate immunity factors, these selfish elements benefit from selective discrimination against recent ancestors, thus facilitating their proliferation and benefiting the host. Whether social diversification benefits the population at large is less obvious. The widespread use of next-generation sequencing has recently provided new insights into population dynamics in natural habitats and the roles MGEs play. MGEs belong to accessory genomes, which often constitute the majority of the pangenome of a taxon, and contain most of the kin-discriminating loci that fuel rapid social diversification. We further discuss mechanisms of diversification and its consequences to populations and conclude with a case study involving myxobacteria.
Topics: Bacteria; Myxococcales; Biological Evolution; Genome; Interspersed Repetitive Sequences
PubMed: 36980919
DOI: 10.3390/genes14030648 -
Nature Communications Sep 2023Many species, such as fish schools or bird flocks, rely on collective motion to forage, prey, or escape predators. Likewise, Myxococcus xanthus forages and moves...
Many species, such as fish schools or bird flocks, rely on collective motion to forage, prey, or escape predators. Likewise, Myxococcus xanthus forages and moves collectively to prey and feed on other bacterial species. These activities require two distinct motility machines enabling adventurous (A) and social (S) gliding, however when and how these mechanisms are used has remained elusive. Here, we address this long-standing question by applying multiscale semantic cell tracking during predation. We show that: (1) foragers and swarms can comprise A- and S-motile cells, with single cells exchanging frequently between these groups; (2) A-motility is critical to ensure the directional movement of both foragers and swarms; (3) the combined action of A- and S-motile cells within swarms leads to increased predation efficiencies. These results challenge the notion that A- and S-motilities are exclusive to foragers and swarms, and show that these machines act synergistically to enhance predation efficiency.
Topics: Animals; Predatory Behavior; Cell Tracking; Cooperative Behavior; Motion; Myxococcus xanthus
PubMed: 37696789
DOI: 10.1038/s41467-023-41193-x -
Pharmaceutics Aug 2021Myxobacteria are unicellular, Gram-negative, soil-dwelling, gliding bacteria that belong to class δ-proteobacteria and order They grow and proliferate by transverse... (Review)
Review
Myxobacteria are unicellular, Gram-negative, soil-dwelling, gliding bacteria that belong to class δ-proteobacteria and order They grow and proliferate by transverse fission under normal conditions, but form fruiting bodies which contain myxospores during unfavorable conditions. In view of the escalating problem of antibiotic resistance among disease-causing pathogens, it becomes mandatory to search for new antibiotics effective against such pathogens from natural sources. Among the different approaches, Myxobacteria, having a rich armor of secondary metabolites, preferably derivatives of polyketide synthases (PKSs) along with non-ribosomal peptide synthases (NRPSs) and their hybrids, are currently being explored as producers of new antibiotics. The species are functionally characterized to assess their ability to produce antibacterial, antifungal, anticancer, antimalarial, immunosuppressive, cytotoxic and antioxidative bioactive compounds. In our study, we have found their compounds to be effective against a wide range of pathogens associated with the concurrence of different infectious diseases.
PubMed: 34452226
DOI: 10.3390/pharmaceutics13081265