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Nature Communications Jun 2023Cell division is spatiotemporally precisely regulated, but the underlying mechanisms are incompletely understood. In the social bacterium Myxococcus xanthus, the...
Cell division is spatiotemporally precisely regulated, but the underlying mechanisms are incompletely understood. In the social bacterium Myxococcus xanthus, the PomX/PomY/PomZ proteins form a single megadalton-sized complex that directly positions and stimulates cytokinetic ring formation by the tubulin homolog FtsZ. Here, we study the structure and mechanism of this complex in vitro and in vivo. We demonstrate that PomY forms liquid-like biomolecular condensates by phase separation, while PomX self-assembles into filaments generating a single large cellular structure. The PomX structure enriches PomY, thereby guaranteeing the formation of precisely one PomY condensate per cell through surface-assisted condensation. In vitro, PomY condensates selectively enrich FtsZ and nucleate GTP-dependent FtsZ polymerization and bundle FtsZ filaments, suggesting a cell division site positioning mechanism in which the single PomY condensate enriches FtsZ to guide FtsZ-ring formation and division. This mechanism shares features with microtubule nucleation by biomolecular condensates in eukaryotes, supporting this mechanism's ancient origin.
Topics: Tubulin; Biomolecular Condensates; Polymerization; Cell Division; Myxococcus xanthus
PubMed: 37380708
DOI: 10.1038/s41467-023-39513-2 -
Frontiers in Microbiology 2023sp. PT13 is a wild strain with multiple predatory properties that prey on multiple model microorganisms preserved in the laboratory. However, the lysis spectrum of PT13...
INTRODUCTION
sp. PT13 is a wild strain with multiple predatory properties that prey on multiple model microorganisms preserved in the laboratory. However, the lysis spectrum of PT13 on typical soil bacteria and its driving effect on soil microecosystems are still unclear.
METHODS
In this study, the lawn predation method was used to determine the predation diameter of 62 typical soil bacteria by myxobacteria PT13 and analyze their lysis spectra.
RESULTS AND DISCUSSION
The results showed that PT13 had a predation diameter greater than 15 mm against typical soil microorganisms such as , , , , and and had an outstanding lysis effect but a significant preference ( < 0.05). Absolute high-throughput sequencing results showed that PT13 predation drove the microcosmic system composed of 16 bacterial genera, with a significant decrease in the Shannon index by 11.8% (CK = 2.04, = 1.80) and a significant increase in the Simpson index by 45.0% (CK = 0.20, = 0.29). The results of principal coordinate analysis (PCoA) showed that myxobacterial addition significantly disturbed the microcosmic microbial community structure (ANOSIM, < 0.05). LEfSe analysis showed that the relative and absolute abundances (copy numbers) of , , , and decreased significantly very likely due to myxobacterial predation ( < 0.05). However, the predatory effect of PT13 also increased the relative or absolute abundances of some species, such as , , and . It can be concluded that PT13 has a broad-spectrum lysis spectrum but poor cleavage ability for , and the interaction between complex microorganisms limits the predation effect of PT13 on some prey bacteria. This in turn allows some prey to coexist with myxobacteria. This paper will lay a theoretical foundation for the regulation of soil microecology dominated by myxobacteria.
PubMed: 37378286
DOI: 10.3389/fmicb.2023.1211756 -
PLoS Genetics Jun 2023C-di-GMP is a bacterial second messenger that regulates diverse processes in response to environmental or cellular cues. The nucleoid-associated protein (NAP) CdbA in...
During heat stress in Myxococcus xanthus, the CdbS PilZ domain protein, in concert with two PilZ-DnaK chaperones, perturbs chromosome organization and accelerates cell death.
C-di-GMP is a bacterial second messenger that regulates diverse processes in response to environmental or cellular cues. The nucleoid-associated protein (NAP) CdbA in Myxococcus xanthus binds c-di-GMP and DNA in a mutually exclusive manner in vitro. CdbA is essential for viability, and CdbA depletion causes defects in chromosome organization, leading to a block in cell division and, ultimately, cell death. Most NAPs are not essential; therefore, to explore the paradoxical cdbA essentiality, we isolated suppressor mutations that restored cell viability without CdbA. Most mutations mapped to cdbS, which encodes a stand-alone c-di-GMP binding PilZ domain protein, and caused loss-of-function of cdbS. Cells lacking CdbA and CdbS or only CdbS were fully viable and had no defects in chromosome organization. CdbA depletion caused post-transcriptional upregulation of CdbS accumulation, and this CdbS over-accumulation was sufficient to disrupt chromosome organization and cause cell death. CdbA depletion also caused increased accumulation of CsdK1 and CsdK2, two unusual PilZ-DnaK chaperones. During CdbA depletion, CsdK1 and CsdK2, in turn, enabled the increased accumulation and toxicity of CdbS, likely by stabilizing CdbS. Moreover, we demonstrate that heat stress, possibly involving an increased cellular c-di-GMP concentration, induced the CdbA/CsdK1/CsdK2/CdbS system, causing a CsdK1- and CsdK2-dependent increase in CdbS accumulation. Thereby this system accelerates heat stress-induced chromosome mis-organization and cell death. Collectively, this work describes a unique system that contributes to regulated cell death in M. xanthus and suggests a link between c-di-GMP signaling and regulated cell death in bacteria.
Topics: Bacterial Proteins; Myxococcus xanthus; Carrier Proteins; Molecular Chaperones; Cell Death; Chromosomes; Cyclic GMP; Protein Binding
PubMed: 37339150
DOI: 10.1371/journal.pgen.1010819 -
IScience Jul 2023Many microbial phenotypes are density-dependent, including group-level phenotypes emerging from cooperation. However, surveys for the presence of a particular form of...
Many microbial phenotypes are density-dependent, including group-level phenotypes emerging from cooperation. However, surveys for the presence of a particular form of density dependence across diverse species are rare, as are direct tests for the Allee effect, i.e., positive density dependence of fitness. Here, we test for density-dependent growth under acid stress in five diverse bacterial species and find the Allee effect in all. Yet social protection from acid stress appears to have evolved by multiple mechanisms. In a strong Allee effect is mediated by pH-regulated secretion of a diffusible molecule by high-density populations. In other species, growth from low density under acid stress was not enhanced by high-density supernatant. In , high cell density may promote predation on other microbes that metabolically acidify their environment, and acid-mediated density dependence may impact the evolution of fruiting-body development. More broadly, high density may protect most bacterial species against acid stress.
PubMed: 37332671
DOI: 10.1016/j.isci.2023.106952 -
Microbiology Spectrum Aug 2023Myxobacteria serve as a treasure trove of secondary metabolites. During our ongoing search for bioactive natural products, a novel subclass of disorazoles termed...
Myxobacteria serve as a treasure trove of secondary metabolites. During our ongoing search for bioactive natural products, a novel subclass of disorazoles termed disorazole Z was discovered. Ten disorazole Z family members were purified from a large-scale fermentation of the myxobacterium Sorangium cellulosum So ce1875 and characterized by electrospray ionization-high-resolution mass spectrometry (ESI-HRMS), X-ray, nuclear magnetic resonance (NMR), and Mosher ester analysis. Disorazole Z compounds are characterized by the lack of one polyketide extension cycle, resulting in a shortened monomer in comparison to disorazole A, which finally forms a dimer in the bis-lactone core structure. In addition, an unprecedented modification of a geminal dimethyl group takes place to form a carboxylic acid methyl ester. The main component disorazole Z1 shows comparable activity in effectively killing cancer cells to disorazole A1 via binding to tubulin, which we show induces microtubule depolymerization, endoplasmic reticulum delocalization, and eventually apoptosis. The disorazole Z biosynthetic gene cluster (BGC) was identified and characterized from the alternative producer So ce427 and compared to the known disorazole A BGC, followed by heterologous expression in the host Myxococcus xanthus DK1622. Pathway engineering by promoter substitution and gene deletion paves the way for detailed biosynthesis studies and efficient heterologous production of disorazole Z congeners. Microbial secondary metabolites are a prolific reservoir for the discovery of bioactive compounds, which prove to be privileged scaffolds for the development of new drugs such as antibacterial and small-molecule anticancer drugs. Consequently, the continuous discovery of novel bioactive natural products is of great importance for pharmaceutical research. Myxobacteria, especially spp., which are known for their large genomes with yet-underexploited biosynthetic potential, are proficient producers of such secondary metabolites. From the fermentation broth of Sorangium cellulosum strain So ce1875, we isolated and characterized a family of natural products named disorazole Z, which showed potent anticancer activity. Further, we report on the biosynthesis and heterologous production of disorazole Z. These results can be stepping stones toward pharmaceutical development of the disorazole family of anticancer natural products for (pre)clinical studies.
Topics: Biological Products; Antineoplastic Agents; Lactones; Myxococcales
PubMed: 37318329
DOI: 10.1128/spectrum.00730-23 -
Applied Microbiology and Biotechnology Aug 2023In our previous work, a recombinant aflatoxin-degrading enzyme derived from Myxococcus fulvus (MADE) was reported. However, the low thermal stability of the enzyme had...
In our previous work, a recombinant aflatoxin-degrading enzyme derived from Myxococcus fulvus (MADE) was reported. However, the low thermal stability of the enzyme had limitations for its use in industrial applications. In this study, we obtained an improved variant of recombinant MADE (rMADE) with enhanced thermostability and catalytic activity using error-prone PCR. Firstly, we constructed a mutant library containing over 5000 individual mutants. Three mutants with T values higher than the wild-type rMADE by 16.5 °C (rMADE-1124), 6.5 °C (rMADE-1795), and 9.8 °C (rMADE-2848) were screened by a high-throughput screening method. Additionally, the catalytic activity of rMADE-1795 and rMADE-2848 was improved by 81.5% and 67.7%, respectively, compared to the wild-type. Moreover, structural analysis revealed that replacement of acidic amino acids with basic amino acids by a mutation (D114H) in rMADE-2848 increased the polar interactions with surrounding residues and resulted in a threefold increase in the t value of the enzyme and made it more thermaltolerate. KEY POINTS: • Mutant libraries construction of a new aflatoxins degrading enzyme by error-prone PCR. • D114H/N295D mutant improved enzyme activity and thermostability. • The first reported enhanced thermostability of aflatoxins degrading enzyme better for its application.
Topics: Aflatoxins; Enzyme Stability; Polymerase Chain Reaction; Mutation; Cloning, Molecular; Temperature
PubMed: 37300712
DOI: 10.1007/s00253-023-12610-4 -
Physical Review Letters May 2023The bacterium Myxococcus xanthus produces multicellular droplets called fruiting bodies when starved. These structures form initially through the active dewetting of a...
The bacterium Myxococcus xanthus produces multicellular droplets called fruiting bodies when starved. These structures form initially through the active dewetting of a vegetative biofilm into surface-associated droplets. This motility-driven aggregation is succeeded by a primitive developmental process in which cells in the droplets mature into nonmotile spores. Here, we use atomic force microscopy to probe the mechanics of these droplets throughout their formation. Using a combination of time- and frequency-domain rheological experiments, we characterize and develop a simple model of the linear viscoelasticity of these aggregates. We then use this model to quantify how cellular behaviors predominant at different developmental times-motility during the dewetting phase and cellular sporulation during later development-manifest as decreased droplet viscosity and increased elasticity, respectively.
Topics: Myxococcus xanthus; Spores, Bacterial; Bacterial Proteins
PubMed: 37295076
DOI: 10.1103/PhysRevLett.130.218402 -
Environmental Pollution (Barking, Essex... Aug 2023The potential of sulphur (S), MgSO (Mg), and KHPO (P) in nitrogen retention, ammonia emission decrease, and microbial community succession during composting needs to be...
The potential of sulphur (S), MgSO (Mg), and KHPO (P) in nitrogen retention, ammonia emission decrease, and microbial community succession during composting needs to be investigated. To achieve this, different levels of S (0, 0.2, 0.4, 0.6, and 0.8% in dry weight) plus Mg and P (S + Mg + P) were progressively added in 70 days pig manure aerobic composting. The results revealed that the amendment increased salinity and lowered pH and dephytotoxication of the product with the increase of S amount. However, no significant inhibition effects were observed on the evolution of the thermophilic phase and product maturity. In addition, the amendment significantly reduced the total NH and NO emissions by 29.66%-58.81% and 20.6%-56.7%, increased NH level by 17.22%-73.21% in thermophilic phase and NO content by 26.17%-57.48% in a mature phase, and elevated the total Kjeldahl nitrogen content by 34.28%-46.6% during the composting. In addition, compared to the control, the supplement markedly encouraged the formation of guanite in the compost product. The S addition stimulated the growth of Anseongella, Actinomadura, Chelativorans, Castellaniella, Luteimonas, and Steroidobacter microbial communities which functioned well in the degradation of nitrogen-containing compounds and organic matter. Evidence from Redundancy Analysis, Firmicutes, Myxococcus, Chloroflexi, Gemmatimonadota, and Deinococcota showed positive correlations with pH. These results imply that adding S-Mg-P amendment encourages the population and activity of specific functional microorganisms, and facilitated the ammonia emission reduction by lowering pH and thus reserved nitrogen through the formation of guanite during composting. The investigation of bacterial community abundance and environmental variables at the phylum and genus levels over time revealed that adding of 0.6% S in conjunction with P and Mg minerals was suitable for nitrogen loss mitigation in composting. The findings suggest using S + Mg + P supplement to conserve nitrogen in pig dung aerobic composting.
Topics: Swine; Animals; Ammonia; Manure; Composting; Soil; Nitrogen; Sulfur; Bacteria
PubMed: 37263560
DOI: 10.1016/j.envpol.2023.121934 -
Genes May 2023By targeting mRNA transcripts, non-coding small RNAs (sRNAs) regulate the expression of genes governing a wide range of bacterial functions. In the social myxobacterium...
By targeting mRNA transcripts, non-coding small RNAs (sRNAs) regulate the expression of genes governing a wide range of bacterial functions. In the social myxobacterium , the sRNA Pxr serves as a gatekeeper of the regulatory pathway controlling the life-cycle transition from vegetative growth to multicellular fruiting body development. When nutrients are abundant, Pxr prevents the initiation of the developmental program, but Pxr-mediated inhibition is alleviated when cells starve. To identify genes essential for Pxr function, a developmentally defective strain in which Pxr-mediated blockage of development is constitutively active (strain "OC") was transposon-mutagenized to identify suppressor mutations that inactivate or bypass Pxr inhibition and thereby restore development. One of the four loci in which a transposon insertion restored development is , encoding the Ribonuclease D protein (RNase D). RNase D is an exonuclease important for tRNA maturation. Here, we show that disruption of abolishes the accumulation of Pxr-S, the product of Pxr processing from a longer precursor form (Pxr-L) and the active inhibitor of development. Additionally, the decrease in Pxr-S caused by disruption was associated with increased accumulation primarily of a longer novel Pxr-specific transcript (Pxr-XL) rather than of Pxr-L. The introduction of a plasmid expressing reverted cells back to OC-like phenotypes in development and Pxr accumulation, indicating that a lack of RNase D alone suppresses the developmental defect of OC. Moreover, an in vitro Pxr-processing assay demonstrated that RNase D processes Pxr-XL into Pxr-L; this implies that overall, Pxr sRNA maturation requires a sequential two-step processing. Collectively, our results indicate that a housekeeping ribonuclease plays a central role in a model form of microbial aggregative development. To our knowledge, this is the first evidence implicating RNase D in sRNA processing.
Topics: Ribonuclease III; RNA, Bacterial; Myxococcales; Suppression, Genetic; RNA, Small Untranslated
PubMed: 37239421
DOI: 10.3390/genes14051061 -
Microbiology Resource Announcements Jun 2023Here, we characterize the genome of phage Mx9, a lysogenic, short-tailed phage (genus ) phage infecting the bacterial host Myxococcus xanthus, a model for bacterial...
Here, we characterize the genome of phage Mx9, a lysogenic, short-tailed phage (genus ) phage infecting the bacterial host Myxococcus xanthus, a model for bacterial evolution and development. The 53.5-kb genome has a GC content of 67.5% and contains 98 predicted protein-coding genes, including the previously characterized site-specific integrase gene ().
PubMed: 37219425
DOI: 10.1128/mra.00221-23