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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 -
RSC Chemical Biology Nov 20238-Azido-3,8-dideoxy-α/β-d--oct-2-ulosonic acid (Kdo-8-N) is a Kdo derivative used in metabolic labeling of lipopolysaccharide (LPS) structures found on the cell...
8-Azido-3,8-dideoxy-α/β-d--oct-2-ulosonic acid (Kdo-8-N) is a Kdo derivative used in metabolic labeling of lipopolysaccharide (LPS) structures found on the cell membrane of Gram-negative bacteria. Several studies have reported successful labeling of LPS using Kdo-8-N and visualization of LPS by a fluorescent reagent through click chemistry on a selection of Gram-negative bacteria such as strains, , and . Motivated by the promise of Kdo-8-N to be useful in the investigation of LPS biosynthesis and cell surface labeling across different strains, we set out to explore the variability in nature and efficiency of LPS labeling using Kdo-8-N in a variety of strains and serotypes. We optimized the chemical synthesis of Kdo-8-N and subsequently used Kdo-8-N to metabolically label pathogenic strains from commercial and clinical origin. Interestingly, different extents of labeling were observed in different strains, which seemed to be dependent also on growth media, and the majority of labeled LPS appears to be of the 'rough' LPS variant, as visualized using SDS-PAGE and fluorescence microscopy. This knowledge is important for future application of Kdo-8-N in the study of LPS biosynthesis and dynamics, especially when working with clinical isolates.
PubMed: 37920390
DOI: 10.1039/d3cb00110e -
PLoS Genetics Sep 2022The Ras-like GTPase MglA is a key regulator of front-rear polarity in the rod-shaped Myxococcus xanthus cells. MglA-GTP localizes to the leading cell pole and stimulates...
The Ras-like GTPase MglA is a key regulator of front-rear polarity in the rod-shaped Myxococcus xanthus cells. MglA-GTP localizes to the leading cell pole and stimulates assembly of the two machineries for type IV pili-dependent motility and gliding motility. MglA-GTP localization is spatially constrained by its cognate GEF, the RomR/RomX complex, and GAP, the MglB Roadblock-domain protein. Paradoxically, RomR/RomX and MglB localize similarly with low and high concentrations at the leading and lagging poles, respectively. Yet, GEF activity dominates at the leading and GAP activity at the lagging pole by unknown mechanisms. Here, we identify RomY and show that it stimulates MglB GAP activity. The MglB/RomY interaction is low affinity, restricting formation of the bipartite MglB/RomY GAP complex almost exclusively to the lagging pole with the high MglB concentration. Our data support a model wherein RomY, by forming a low-affinity complex with MglB, ensures that the high MglB/RomY GAP activity is confined to the lagging pole where it dominates and outcompetes the GEF activity of the RomR/RomX complex. Thereby, MglA-GTP localization is constrained to the leading pole establishing front-rear polarity.
Topics: Bacterial Proteins; Cell Polarity; GTP Phosphohydrolases; Guanosine Triphosphate; Myxococcus xanthus
PubMed: 36067225
DOI: 10.1371/journal.pgen.1010384 -
Journal of Bacteriology Jun 2021In bacteria, the nucleotide-based second messenger bis-(3'-5')-cyclic dimeric GMP (c-di-GMP) binds to effectors to generate outputs in response to changes in the...
In bacteria, the nucleotide-based second messenger bis-(3'-5')-cyclic dimeric GMP (c-di-GMP) binds to effectors to generate outputs in response to changes in the environment. In Myxococcus xanthus, c-di-GMP regulates type IV pilus-dependent motility and the starvation-induced developmental program that results in formation of spore-filled fruiting bodies; however, little is known about the effectors that bind c-di-GMP. Here, we systematically inactivated all 24 genes encoding PilZ domain-containing proteins, which are among the most common c-di-GMP effectors. We confirm that the stand-alone PilZ domain protein PlpA is important for regulation of motility independently of the Frz chemosensory system and that Pkn1, which is composed of a Ser/Thr kinase domain and a PilZ domain, is specifically important for development. Moreover, we identify two PilZ domain proteins that have distinct functions in regulating motility and development. PixB, which is composed of two PilZ domains and an acetyltransferase domain, binds c-di-GMP and regulates type IV pilus-dependent and gliding motility in a Frz-dependent manner as well as development. The acetyltransferase domain is required and sufficient for function during growth, while all three domains and c-di-GMP binding are essential for PixB function during development. PixA is a response regulator composed of a PilZ domain and a receiver domain, binds c-di-GMP , and regulates motility independently of the Frz system, likely by setting up the polarity of the two motility systems. Our results support a model whereby PlpA, PixA, and PixB act in independent pathways and have distinct functions in regulation of motility. c-di-GMP signaling controls bacterial motility in many bacterial species by binding to downstream effector proteins. Here, we identify two PilZ domain-containing proteins in Myxococcus xanthus that bind c-di-GMP. We show that PixB, which contains two PilZ domains and an acetyltransferase domain, acts in a manner that depends on the Frz chemosensory system to regulate motility via the acetyltransferase domain, while the intact protein and c-di-GMP binding are essential for PixB to support development. In contrast, PixA acts in a Frz-independent manner to regulate motility. Taking our results together with previous observations, we conclude that PilZ domain proteins and c-di-GMP act in multiple independent pathways to regulate motility and development in M. xanthus.
Topics: Bacterial Proteins; Cyclic GMP; Fimbriae, Bacterial; Gene Expression Regulation, Bacterial; Myxococcus xanthus; Protein Binding; Protein Domains
PubMed: 33875546
DOI: 10.1128/JB.00126-21 -
Experimental Biology and Medicine... 2024Currently, various functionalized nanocarrier systems are extensively studied for targeted delivery of drugs, peptides, and nucleic acids. Joining the approaches of...
Currently, various functionalized nanocarrier systems are extensively studied for targeted delivery of drugs, peptides, and nucleic acids. Joining the approaches of genetic and chemical engineering may produce novel carriers for precise targeting different cellular proteins, which is important for both therapy and diagnosis of various pathologies. Here we present the novel nanocontainers based on vectorized genetically encoded (Mx) encapsulin, confining a fluorescent photoactivatable mCherry (PAmCherry) protein. The shells of such encapsulins were modified using chemical conjugation of human transferrin (Tf) prelabeled with a fluorescein-6 (FAM) maleimide acting as a vector. We demonstrate that the vectorized encapsulin specifically binds to transferrin receptors (TfRs) on the membranes of mesenchymal stromal/stem cells (MSCs) followed by internalization into cells. Two spectrally separated fluorescent signals from Tf-FAM and PAmCherry are clearly distinguishable and co-localized. It is shown that Tf-tagged Mx encapsulins are internalized by MSCs much more efficiently than by fibroblasts. It has been also found that unlabeled Tf effectively competes with the conjugated Mx-Tf-FAM formulations. That indicates the conjugate internalization into cells by Tf-TfR endocytosis pathway. The developed nanoplatform can be used as an alternative to conventional nanocarriers for targeted delivery of, e.g., genetic material to MSCs.
Topics: Mesenchymal Stem Cells; Transferrin; Humans; Myxococcus xanthus; Endocytosis; Receptors, Transferrin; Luminescent Proteins
PubMed: 38774281
DOI: 10.3389/ebm.2024.10055 -
Journal of Bacteriology Feb 2016When starved for nutrients, Myxococcus xanthus produces a biofilm that contains a mat of rod-shaped cells, known as peripheral rods, and aerial structures called... (Review)
Review
When starved for nutrients, Myxococcus xanthus produces a biofilm that contains a mat of rod-shaped cells, known as peripheral rods, and aerial structures called fruiting bodies, which house thousands of dormant and stress-resistant spherical spores. Because rod-shaped cells differentiate into spherical, stress-resistant spores and spore differentiation occurs only in nascent fruiting bodies, many genes and multiple levels of regulation are required. Over the past 2 decades, many regulators of the temporal and spatial expression of M. xanthus sporulation genes have been uncovered. Of these sporulation gene regulators, two-component signal transduction circuits, which typically contain a histidine kinase sensor protein and a transcriptional regulator known as response regulator, are among the best characterized. In this review, we discuss prototypical two-component systems (Nla6S/Nla6 and Nla28S/Nla28) that regulate an early, preaggregation phase of sporulation gene expression during fruiting body development. We also discuss orphan response regulators (ActB and FruA) that regulate a later phase of sporulation gene expression, which begins during the aggregation stage of fruiting body development. In addition, we summarize the research on a complex two-component system (Esp) that is important for the spatial regulation of sporulation.
Topics: Gene Expression Regulation, Bacterial; Myxococcus xanthus; Signal Transduction; Spores, Bacterial; Time Factors
PubMed: 26369581
DOI: 10.1128/JB.00474-15 -
Journal of Natural Products Mar 2017This review focuses entirely on the natural bengamides and selected synthetic analogues that have inspired decades of research. Bengamide A was first reported in 1986... (Review)
Review
This review focuses entirely on the natural bengamides and selected synthetic analogues that have inspired decades of research. Bengamide A was first reported in 1986 from the sponge Jaspis cf. coriacea, and bengamide-containing sponges have been gathered from many biogeographic sites. In 2005, a terrestrial Gram-negative bacterium, Myxococcus virescens, was added as a source for bengamides. Biological activity data using varying bengamide-based scaffolds has enabled fine-tuning of structure-activity relationships. Molecular target finding contributed to the creation of a synthetic "lead" compound, LAF389, that was the subject of a phase I anticancer clinical trial. Despite clinical trial termination, the bengamide compound class is still attracting worldwide attention. Future breakthroughs based on the bengamide scaffold are possible and could build on their nanomolar in vitro and positive in vivo antiproliferative and antiangiogenic properties. Bengamide molecular targets include methionine aminopeptidases (MetAP1 and MetAP2) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB). A mixed PKS/NRPS biosynthetic gene cluster appears to be responsible for creation of the bengamides. This review highlights that the bengamides have driven inspirational studies and that they will remain relevant for future research, even 30 years after the discovery of the first structures.
Topics: Aminopeptidases; Angiogenesis Inhibitors; Animals; Azepines; Humans; Metalloendopeptidases; Methionyl Aminopeptidases; Molecular Structure; NF-kappa B; Porifera
PubMed: 28185457
DOI: 10.1021/acs.jnatprod.6b00970 -
Sheng Wu Gong Cheng Xue Bao = Chinese... Sep 2017Myxococcus xanthus is a Gram-negative soil bacterium capable of performing sophisticated cellular behaviors and growing one of the most intricate bacterial... (Review)
Review
Myxococcus xanthus is a Gram-negative soil bacterium capable of performing sophisticated cellular behaviors and growing one of the most intricate bacterial single-species biofilms in nature. During the process of biofilm formation, social behaviors of M. xanthus cells dominate key steps of the biofilm establishment, e.g., cellular motility on solid surface, predatory behavior by the grouped cells, kin recognition in the community, fruiting body development, myxospore differentiation, and programmed cell death. This review introduces the recent research progress about the M. xanthus biofilms.
Topics: Biofilms; Microbial Interactions; Myxococcus xanthus
PubMed: 28956403
DOI: 10.13345/j.cjb.170201 -
Bio-protocol Jul 2023In the environment, bacteria compete for niche occupancy and resources; they have, therefore, evolved a broad variety of antibacterial weapons to destroy competitors....
In the environment, bacteria compete for niche occupancy and resources; they have, therefore, evolved a broad variety of antibacterial weapons to destroy competitors. Current laboratory techniques to evaluate antibacterial activity are usually labor intensive, low throughput, costly, and time consuming. Typical assays rely on the outgrowth of colonies of prey cells on selective solid media after competition. Here, we present fast, inexpensive, and complementary optimized protocols to qualitatively and quantitively measure antibacterial activity. The first method is based on the degradation of a cell-impermeable chromogenic substrate of the β-galactosidase, a cytoplasmic enzyme released during lysis of the attacked reporter strain. The second method relies on the lag time required for the attacked cells to reach a defined optical density after the competition, which is directly dependent on the initial number of surviving cells. Key features First method utilizes the release of β-galactosidase as a proxy for bacterial lysis. Second method is based on the growth timing of surviving cells. Combination of two methods discriminates between cell death and lysis, cell death without lysis, or survival to quasi-lysis. Methods optimized to various bacterial species such as , and . Graphical overview.
PubMed: 37449039
DOI: 10.21769/BioProtoc.4706 -
Scientific Reports Feb 2021Bacterial-derived polyketide and non-ribosomal peptide natural products are crucial sources of therapeutics and yet little is known about the conditions that favor...
Bacterial-derived polyketide and non-ribosomal peptide natural products are crucial sources of therapeutics and yet little is known about the conditions that favor activation of natural product genes or the regulatory machinery controlling their transcription. Recent findings suggest that the σ system, which includes σ-loaded RNA polymerase and transcriptional activators called enhancer binding proteins (EBPs), might be a common regulator of natural product genes. Here, we explored this idea by analyzing a selected group of putative σ promoters identified in Myxococcus xanthus natural product gene clusters. We show that mutations in putative σ-RNA polymerase binding regions and in putative Nla28 EBP binding sites dramatically reduce in vivo promoter activities in growing and developing cells. We also show in vivo promoter activities are reduced in a nla28 mutant, that Nla28 binds to wild-type fragments of these promoters in vitro, and that in vitro binding is lost when the Nla28 binding sites are mutated. Together, our results indicate that M. xanthus uses σ promoters for transcription of at least some of its natural product genes. Interestingly, the vast majority of experimentally confirmed and putative σ promoters in M. xanthus natural product loci are located within genes and not in intergenic sequences.
Topics: Bacterial Proteins; Gene Expression Regulation, Bacterial; Multigene Family; Myxococcus xanthus; Promoter Regions, Genetic; RNA Polymerase Sigma 54; Transcriptional Activation
PubMed: 33637792
DOI: 10.1038/s41598-021-84057-4