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PLoS Computational Biology Jan 2021The mechanisms and design principles of regulatory systems establishing stable polarized protein patterns within cells are well studied. However, cells can also...
The mechanisms and design principles of regulatory systems establishing stable polarized protein patterns within cells are well studied. However, cells can also dynamically control their cell polarity. Here, we ask how an upstream signaling system can switch the orientation of a polarized pattern. We use a mathematical model of a core polarity system based on three proteins as the basis to study different mechanisms of signal-induced polarity switching. The analysis of this model reveals four general classes of switching mechanisms with qualitatively distinct behaviors: the transient oscillator switch, the reset switch, the prime-release switch, and the push switch. Each of these regulatory mechanisms effectively implements the function of a spatial toggle switch, however with different characteristics in their nonlinear and stochastic dynamics. We identify these characteristics and also discuss experimental signatures of each type of switching mechanism.
Topics: Bacterial Proteins; Cell Polarity; Computational Biology; Gene Regulatory Networks; Intercellular Signaling Peptides and Proteins; Membrane Proteins; Models, Biological; Myxococcus xanthus; Signal Transduction; Stochastic Processes
PubMed: 33465073
DOI: 10.1371/journal.pcbi.1008587 -
Current Opinion in Microbiology Aug 2020Myxobacteria conduct complex social traits that requires populations to be highly related and devoid of exploiters. To enrich for clonal cells in populations, they... (Review)
Review
Myxobacteria conduct complex social traits that requires populations to be highly related and devoid of exploiters. To enrich for clonal cells in populations, they employ kin discrimination mechanisms. One key system involves a polymorphic cell surface receptor, TraA, which recognizes self by homotypic interactions with neighboring myxobacterial cells. Recent studies revealed that TraA and its partner TraB are fluid outer membrane proteins that coalesce into foci upon recognition of kin. The formation of foci leads to transient membrane fusion junctions and the bidirectional exchange of outer membrane components that facilitates cooperative behaviors. Additionally, expansive suites of polymorphic lipoprotein toxins are exchanged, which act as self-identity barcodes that exquisitely discriminate against nonself to assemble homogenous populations.
Topics: Bacterial Proteins; Cell Membrane; Myxococcales; Receptors, Cell Surface
PubMed: 32828979
DOI: 10.1016/j.mib.2020.07.003 -
Marine Drugs Aug 2018Over the last two decades, halophilic (organisms that thrive at high salt concentrations) and halotolerant (organisms that have adapted to high salt concentrations)... (Review)
Review
Over the last two decades, halophilic (organisms that thrive at high salt concentrations) and halotolerant (organisms that have adapted to high salt concentrations) myxobacteria emerged as an important source of structurally diverse secondary metabolites from the marine environment. This review explores the advance of metagenomics analysis and 16S rRNA gene phylogeny of the cultured and uncultured myxobacteria from marine and other salt-environments up to July 2018. The diversity of novel groups of myxobacteria in these environments appears unprecedented, especially in the and suborders. The related clade in the suborder seems more widely distributed compared to the exclusively marine myxobacterial cluster. Some of the previously identified clones from metagenomic studies were found to be related to the suborder. This understanding provides the foundation for a vital, unexplored resource. Understanding the conditions required to cultivate these yet "uncultured" myxobacteria in the laboratory, while a key next step, offers a significant potential to further expand access to diverse secondary metabolites.
Topics: Aquatic Organisms; Biodiversity; Biological Products; DNA, Bacterial; Metagenomics; Myxococcales; Phylogeny; RNA, Ribosomal, 16S; Salt Tolerance; Sequence Analysis, DNA
PubMed: 30158489
DOI: 10.3390/md16090303 -
Microbiology Spectrum Aug 2023Polyp bail-out constitutes both a stress response and an asexual reproductive strategy that potentially facilitates dispersal of some scleractinian corals, including...
Polyp bail-out constitutes both a stress response and an asexual reproductive strategy that potentially facilitates dispersal of some scleractinian corals, including several dominant reef-building taxa in the family Pocilloporidae. Recent studies have proposed that microorganisms may be involved in onset and progression of polyp bail-out. However, changes in the coral microbiome during polyp bail-out have not been investigated. In this study, we induced polyp bail-out in corals using hypersaline and hyperthermal methods. Bacterial community dynamics during bail-out induction were examined using the V5-V6 region of the 16S-rRNA gene. From 70 16S-rRNA gene libraries constructed from coral tissues, 1,980 OTUs were identified. and consistently constituted the dominant bacterial taxa in all coral tissue samples. Onset of polyp bail-out was characterized by increased relative abundance of and decreased abundance of in both induction experiments, with the shift being more prominent in response to elevated temperature than to elevated salinity. Four OTUs, affiliated with , , , and , showed concurrent abundance increases at the onset of polyp bail-out in both experiments, suggesting potential microbial causes of this coral stress response. Polyp bail-out represents both a stress response and an asexual reproductive strategy with significant implications for reshaping tropical coral reefs in response to global climate change. Although earlier studies have suggested that coral-associated microbiomes likely contribute to initiation of polyp bail-out in scleractinian corals, there have been no studies of coral microbiome shifts during polyp bail-out. In this study, we present the first investigation of changes in bacterial symbionts during two experiments in which polyp bail-out was induced by different environmental stressors. These results provide a background of coral microbiome dynamics during polyp bail-out development. Increases in abundance of , , , and that occurred in both experiments suggest that these bacteria are potential microbial causes of polyp bail-out, shedding light on the proximal triggering mechanism of this coral stress response.
Topics: Animals; Anthozoa; Coral Reefs; Microbiota; Gammaproteobacteria; Rhodobacteraceae; Myxococcales; RNA, Ribosomal, 16S
PubMed: 37378544
DOI: 10.1128/spectrum.00257-23 -
Research (Washington, D.C.) 2022Microbial contributions to natural soil suppressiveness have been reported for a range of plant pathogens and cropping systems. To disentangle the mechanisms underlying...
Microbial contributions to natural soil suppressiveness have been reported for a range of plant pathogens and cropping systems. To disentangle the mechanisms underlying suppression of banana Panama disease caused by f. sp. tropical race 4 (Foc4), we used amplicon sequencing to analyze the composition of the soil microbiome from six separate locations, each comprised of paired orchards, one potentially suppressive and one conducive to the disease. Functional potentials of the microbiomes from one site were further examined by shotgun metagenomic sequencing after soil suppressiveness was confirmed by greenhouse experiments. Potential key antagonists involved in disease suppression were also isolated, and their activities were validated by a combination of microcosm and pot experiments. We found that potentially suppressive soils shared a common core community with relatively low levels of and relatively high proportions of Myxococcales, Pseudomonadales, and Xanthomonadales, with five genera, , , , , and being significantly enriched. Further, was identified as a potential key taxon linked to pathogen suppression. Metagenomic analysis showed that, compared to the conducive soil, the microbiome in the disease suppressive soil displayed a significantly greater incidence of genes related to quorum sensing, biofilm formation, and synthesis of antimicrobial compounds potentially active against Foc4. We also recovered a higher frequency of antagonistic isolates from disease suppressive experimental field sites, and their protective effects against banana wilt disease were demonstrated under greenhouse conditions. Despite differences in location and soil conditions, separately located suppressive soils shared common characteristics, including enrichment of Myxococcales, Pseudomonadales, and Xanthomonadales, and enrichment of specific populations with antagonistic activity against the pathogen. Moreover, changes in functional capacity toward an increase in quorum sensing, biofilm formation, and antimicrobial compound synthesizing involve in disease suppression.
PubMed: 36204250
DOI: 10.34133/2022/9818073 -
Current Biology : CB Dec 2020Many microbes produce stress-resistant spores to survive unfavorable conditions [1-4] and enhance dispersal [1, 5]. Cooperative behavior is integral to the process of...
Many microbes produce stress-resistant spores to survive unfavorable conditions [1-4] and enhance dispersal [1, 5]. Cooperative behavior is integral to the process of spore formation in some species [3, 6], but the degree to which germination of spore populations involves social interactions remains little explored. Myxococcus xanthus is a predatory soil bacterium that upon starvation forms spore-filled multicellular fruiting bodies that often harbor substantial diversity of endemic origin [7, 8]. Here we demonstrate that germination of M. xanthus spores formed during fruiting-body development is a social process involving at least two functionally distinct social molecules. Using pairs of natural isolates each derived from a single fruiting body that emerged on soil, we first show that spore germination exhibits positive density dependence due to a secreted "public-good" germination factor. Further, we find that a germination defect of one strain under saline stress in pure culture is complemented by addition of another strain that germinates well in saline environments and mediates cheating by the defective strain. Glycine betaine, an osmo-protectant utilized in all domains of life, is found to mediate saline-specific density dependence and cheating. Density dependence in non-saline conditions is mediated by a distinct factor, revealing socially complex spore germination involving multiple social molecules.
Topics: Betaine; Myxococcus xanthus; Quorum Sensing; Soil Microbiology; Spores, Bacterial
PubMed: 32976811
DOI: 10.1016/j.cub.2020.08.091 -
Nature Communications Sep 2023Peptidoglycan (PG) defines cell shape and protects bacteria against osmotic stress. The growth and integrity of PG require coordinated actions between synthases that...
Peptidoglycan (PG) defines cell shape and protects bacteria against osmotic stress. The growth and integrity of PG require coordinated actions between synthases that insert new PG strands and hydrolases that generate openings to allow the insertion. However, the mechanisms of their coordination remain elusive. Moenomycin that inhibits a family of PG synthases known as Class-A penicillin-binding proteins (aPBPs), collapses rod shape despite aPBPs being non-essential for rod-like morphology in the bacterium Myxococcus xanthus. Here, we demonstrate that inhibited PBP1a2, an aPBP, accelerates the degradation of cell poles by DacB, a hydrolytic PG peptidase. Moenomycin promotes the binding between DacB and PG and thus reduces the mobility of DacB through PBP1a2. Conversely, DacB also regulates the distribution and dynamics of aPBPs. Our findings clarify the action of moenomycin and suggest that disrupting the coordination between PG synthases and hydrolases could be more lethal than eliminating individual enzymes.
Topics: Peptidoglycan; Bambermycins; Nitric Oxide Synthase; Peptide Hydrolases; Cell Wall; Myxococcus xanthus; Penicillin-Binding Proteins
PubMed: 37660104
DOI: 10.1038/s41467-023-41082-3 -
Cells Nov 2022Understanding the intrinsic mechanisms of bacterial competition is a fundamental question. Iron is an essential trace nutrient that bacteria compete for. The most...
BACKGROUND
Understanding the intrinsic mechanisms of bacterial competition is a fundamental question. Iron is an essential trace nutrient that bacteria compete for. The most prevalent manner for iron scavenging is through the secretion of siderophores. Although tremendous efforts have focused on elucidating the molecular mechanisms of siderophores biosynthesis, export, uptake, and regulation of siderophores, the ecological aspects of siderophore-mediated competition are not well understood.
METHODS
We performed predation and bacterial competition assays to investigate the function of siderophore transport on myxobacterial predation.
RESULTS
Deletion of , which encodes an iron chelate uptake ABC transporter family permease subunit, led to a reduction in myxobacterial predation and intracellular iron, but iron deficiency was not the predominant reason for the decrease in the predation ability of the ∆ mutant. We further confirmed that obstruction of siderophore transport decreased myxobacterial predation by investigating the function of a non-ribosomal peptide synthetase for siderophore biosynthesis, a TonB-dependent receptor, and a siderophore binding protein in . Our results showed that the obstruction of siderophores transport decreased myxobacterial predation ability through the downregulation of lytic enzyme genes, especially outer membrane vesicle (OMV)-specific proteins.
CONCLUSIONS
This work provides insight into the mechanism of siderophore-mediated competition in myxobacteria.
Topics: Myxococcales; Bacterial Proteins; Siderophores; Iron; Membrane Proteins; Bacteria; ATP-Binding Cassette Transporters
PubMed: 36496980
DOI: 10.3390/cells11233718 -
PLoS Biology Jan 2024Ecological variation influences the character of many biotic interactions, but examples of predator-prey reversal mediated by abiotic context are few. We show that the...
Ecological variation influences the character of many biotic interactions, but examples of predator-prey reversal mediated by abiotic context are few. We show that the temperature at which prey grow before interacting with a bacterial predator can determine the very direction of predation, reversing predator and prey identities. While Pseudomonas fluorescens reared at 32°C was extensively killed by the generalist predator Myxococcus xanthus, P. fluorescens reared at 22°C became the predator, slaughtering M. xanthus to extinction and growing on its remains. Beyond M. xanthus, diffusible molecules in P. fluorescens supernatant also killed 2 other phylogenetically distant species among several examined. Our results suggest that the sign of lethal microbial antagonisms may often change across abiotic gradients in natural microbial communities, with important ecological and evolutionary implications. They also suggest that a larger proportion of microbial warfare results in predation-the killing and consumption of organisms-than is generally recognized.
Topics: Animals; Predatory Behavior; Antibiosis; Biological Evolution; Microbiota; Myxococcus xanthus
PubMed: 38261596
DOI: 10.1371/journal.pbio.3002454 -
Molecules (Basel, Switzerland) Mar 2023The hard-to-culture slightly halophilic myxobacterium "" SMH-27-4 produces antifungal cyclodepsipeptide miuraenamide A (). Herein, the region (85.9 kbp) containing the...
The hard-to-culture slightly halophilic myxobacterium "" SMH-27-4 produces antifungal cyclodepsipeptide miuraenamide A (). Herein, the region (85.9 kbp) containing the biosynthetic gene cluster (BGC) coding the assembly of was identified and heterologously expressed in A biosynthetic pathway proposed using in silico analysis was verified through the gene disruption of the heterologous transformant. In addition to the core polyketide synthase (PKS) and nonribosomal peptide synthase (NRPS) genes, tyrosine halogenase and -methyltransferase genes participated in the biosynthesis of as their gene-disrupted mutants produced a new congener, debromomiuraenamide A (), and a previously isolated congener, miuraenamide E (), respectively. Multigene disruption provided a heterologous mutant that produced with the highest yield among the prepared mutants. When fed on 3-bromo-L-tyrosine, this mutant produced more in the yield of 1.21 mg/L, which was 20 times higher than that produced by the initially prepared heterologous transformant. Although this yield was comparable to that of the original producer SMH-27-4 (1 mg/L), the culture time was 4.5 times shorter than that of SMH-27-4, indicating a five-fold efficiency in productivity. The results indicate the great potential of the miuraenamide BGC for the future contribution to drug development through logical gene manipulation.
Topics: Anti-Bacterial Agents; Myxococcales; Depsipeptides; Polyketide Synthases; Multigene Family
PubMed: 36985787
DOI: 10.3390/molecules28062815