-
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 -
Journal of Molecular Biology Nov 2015Prokaryotes often reside in groups where a high degree of relatedness has allowed the evolution of cooperative behaviors. However, very few bacteria or archaea have made... (Review)
Review
Prokaryotes often reside in groups where a high degree of relatedness has allowed the evolution of cooperative behaviors. However, very few bacteria or archaea have made the successful transition from unicellular to obligate multicellular life. A notable exception is the myxobacteria, in which cells cooperate to perform group functions highlighted by fruiting body development, an obligate multicellular function. Like all multicellular organisms, myxobacteria face challenges in how to organize and maintain multicellularity. These challenges include maintaining population homeostasis, carrying out tissue repair and regulating the behavior of non-cooperators. Here, we describe the major cooperative behaviors that myxobacteria use: motility, predation and development. In addition, this review emphasizes recent discoveries in the social behavior of outer membrane exchange, wherein kin share outer membrane contents. Finally, we review evidence that outer membrane exchange may be involved in regulating population homeostasis, thus serving as a social tool for myxobacteria to make the cyclic transitions from unicellular to multicellular states.
Topics: Bacterial Outer Membrane Proteins; Myxococcales
PubMed: 26254571
DOI: 10.1016/j.jmb.2015.07.022 -
Molecular Microbiology Jul 2016For many bacteria, motility is essential for survival, growth, virulence, biofilm formation and intra/interspecies interactions. Since natural environments differ,... (Review)
Review
For many bacteria, motility is essential for survival, growth, virulence, biofilm formation and intra/interspecies interactions. Since natural environments differ, bacteria have evolved remarkable motility systems to adapt, including swimming in aqueous media, and swarming, twitching and gliding on solid and semi-solid surfaces. Although tremendous advances have been achieved in understanding swimming and swarming motilities powered by flagella, and twitching motility powered by Type IV pili, little is known about gliding motility. Bacterial gliders are a heterogeneous group containing diverse bacteria that utilize surface motilities that do not depend on traditional flagella or pili, but are powered by mechanisms that are less well understood. Recently, advances in our understanding of the molecular machineries for several gliding bacteria revealed the roles of modified ion channels, secretion systems and unique machinery for surface movements. These novel mechanisms provide rich source materials for studying the function and evolution of complex microbial nanomachines. In this review, we summarize recent findings made on the gliding mechanisms of the myxobacteria, flavobacteria and mycoplasmas.
Topics: Cell Movement; Flavobacteriaceae; Models, Biological; Movement; Mycoplasma; Myxococcales; Secretory Pathway; Virulence
PubMed: 27028358
DOI: 10.1111/mmi.13389 -
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 -
Viruses Jul 2018Bacteriophages have been used as molecular tools in fundamental biology investigations for decades. Beyond this, however, they play a crucial role in the... (Review)
Review
Bacteriophages have been used as molecular tools in fundamental biology investigations for decades. Beyond this, however, they play a crucial role in the eco-evolutionary dynamics of bacterial communities through their demographic impact and the source of genetic information they represent. The increasing interest in describing ecological and evolutionary aspects of bacteria⁻phage interactions has led to major insights into their fundamental characteristics, including arms race dynamics and acquired bacterial immunity. Here, we review knowledge on the phages of the myxobacteria with a major focus on phages infecting , a bacterial model system widely used to study developmental biology and social evolution. In particular, we focus upon the isolation of myxophages from natural sources and describe the morphology and life cycle parameters, as well as the molecular genetics and genomics of the major groups of myxophages. Finally, we propose several interesting research directions which focus on the interplay between myxobacterial host sociality and bacteria⁻phage interactions.
Topics: Bacteriophages; Evolution, Molecular; Gene Expression Regulation, Bacterial; Genome, Viral; Myxococcus xanthus; Sewage; Soil Microbiology
PubMed: 30021959
DOI: 10.3390/v10070374 -
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 -
Microbiology (Reading, England) Jan 2016Myxococcus xanthus is a predatory bacterium and a model system for social behaviour in bacteria. Myx. xanthus forms thin biofilms, where cells work together to colonize... (Review)
Review
Myxococcus xanthus is a predatory bacterium and a model system for social behaviour in bacteria. Myx. xanthus forms thin biofilms, where cells work together to colonize new territory, invade prey colonies and lyse prey cells. Prey-cell lysis occurs at close proximity, and utilizes antibiotics such as myxovirescin, hydrolytic enzymes such as the protease MepA and extracellular outer-membrane vesicles that may facilitate delivery. Many questions about the mechanism of prey lysis remain, as well as a complete understanding of the vast hydrolytic and secondary metabolite potential present in the Myx. xanthus genome. However, it is clear that predation presents unique challenges for this bacterium, which are solved, in part, through the social behaviours at the disposal of Myx. xanthus. Here, we discuss the life cycle of Myx. xanthus, and the hypothesis that multicellular behaviour in this organism is critical to, and derives from, the challenges of growth as a bacterial predator.
Topics: Bacterial Proteins; Myxococcus xanthus; Spores, Fungal
PubMed: 26518442
DOI: 10.1099/mic.0.000208