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Frontiers in Microbiology 2023MrpC, a member of the CRP/Fnr transcription factor superfamily, is necessary to induce and control the multicellular developmental program of the bacterium, . During...
INTRODUCTION
MrpC, a member of the CRP/Fnr transcription factor superfamily, is necessary to induce and control the multicellular developmental program of the bacterium, . During development, certain cells in the population first swarm into haystack-shaped aggregates and then differentiate into environmentally resistant spores to form mature fruiting bodies (a specialized biofilm). transcriptional regulation is controlled by negative autoregulation (NAR).
METHODS
Wild type and mutant promoter regions were fused to a fluorescent reporter to examine effects on expression in the population and in single cells . Phenotypic consequences of the mutant promoter were assayed by deep convolution neural network analysis of developmental movies, sporulation efficiency assays, and anti-MrpC immunoblot. In situ analysis of single cell MrpC levels in distinct populations were assayed with an MrpC-mNeonGreen reporter.
RESULTS
Disruption of MrpC binding sites within the promoter region led to increased and broadened distribution of expression levels between individual cells in the population. Expression of from the mutant promoter led to a striking phenotype in which cells lose synchronized transition from aggregation to sporulation. Instead, some cells abruptly exit aggregation centers and remain locked in a cohesive swarming state we termed developmental swarms, while the remaining cells transition to spores inside residual fruiting bodies. examination of a fluorescent reporter for MrpC levels in developmental subpopulations demonstrated cells locked in the developmental swarms contained MrpC levels that do not reach the levels observed in fruiting bodies.
DISCUSSION
Increased cell-to-cell variation in expression upon disruption of MrpC binding sites within its promoter is consistent with NAR motifs functioning to reducing noise. Noise reduction may be key to synchronized transition of cells in the aggregation state to the sporulation state. We hypothesize a novel subpopulation of cells trapped as developmental swarms arise from intermediate levels of MrpC that are sufficient to promote aggregation but insufficient to trigger sporulation. Failure to transition to higher levels of MrpC necessary to induce sporulation may indicate cells in developmental swarms lack an additional positive feedback signal required to boost MrpC levels.
PubMed: 38075919
DOI: 10.3389/fmicb.2023.1293966 -
Frontiers in Microbiology 2023The soil-dwelling delta-proteobacterium is a model organism to study predation and competition. preys on a broad range of bacteria mediated by lytic enzymes,...
The soil-dwelling delta-proteobacterium is a model organism to study predation and competition. preys on a broad range of bacteria mediated by lytic enzymes, exopolysaccharides, Type-IV pilus-based motility, and specialized metabolites. Competition between and prey bacterial strains with various specialized metabolite profiles indicates a range of fitness, suggesting that specialized metabolites contribute to prey survival. To expand our understanding of how specialized metabolites affect predator-prey dynamics, we assessed interspecies interactions between and two strains of . While strain ATCC 14579 resisted predation, strain T was found to be highly sensitive to predation. The interaction between ATCC 14579 and appears to be competitive, resulting in population loss for both predator and prey. Genome analysis revealed that ATCC 14579 belongs to a clade that possesses the biosynthetic gene cluster for production of thiocillins, whereas strain T lacks those genes. Further, purified thiocillin protects strains unable to produce this specialized metabolite, strengthening the finding that thiocillin protects against predation and contributes to the ecological fitness of ATCC 14579. Lastly, strains that produce thiocillin appear to confer some level of protection to their own antibiotic by encoding an additional copy of the L11 ribosomal protein, a known target for thiopeptides. This work highlights the importance of specialized metabolites affecting predator-prey dynamics in soil microenvironments.
PubMed: 38075900
DOI: 10.3389/fmicb.2023.1295262 -
Microbiology Resource Announcements Dec 2023is the best-studied member of the phylum Myxococcota, but the bacteriophages infecting it and their characterization remain limited. Here, we present complete genomes...
is the best-studied member of the phylum Myxococcota, but the bacteriophages infecting it and their characterization remain limited. Here, we present complete genomes of Mx1, the first phage isolated, and of an Mx4 derivative widely used for generalized transduction, both unclassified Caudoviricetes with long, contractile tails.
PubMed: 38009928
DOI: 10.1128/MRA.00904-23 -
Access Microbiology 2023Myxobacteria produce a variety of bioactive secondary metabolites, and with a wealth of under-researched species they hold vast potential for undiscovered compounds....
Identification of secondary metabolites containing a diketopiperazine core in extracts from myxobacterial strains with growth inhibition activity against a range of prey species.
Myxobacteria produce a variety of bioactive secondary metabolites, and with a wealth of under-researched species they hold vast potential for undiscovered compounds. With the ever-increasing need for new antibiotics, the development of novel therapeutics is vitally important. Therefore, this study aimed to extract and elucidate antimicrobial metabolites from the following myxobacteria: CA010 and AB022; DSM 14696; DSM 14675; and AB050A. Metabolite mixtures were extracted in acetone from XAD-16 resin incubated in liquid cultures and analysed using GC-MS. Bioactivity was identified using a growth inhibition assay against a panel of clinically relevant prey species including Gram-positive and Gram-negative bacteria and a fungus. Growth of and was most affected by the metabolite mixtures and the mixtures from AB022 and AB050A were effective against the most prey. GC-MS analysis revealed metabolites with roles in the synthesis and degradation of amino acids and fatty acids, but also identified compounds A and B with a diketopiperazine (DKP) core. With previously confirmed bioactivity of compound A, it is suggested that these DKP compounds are contributing to the antimicrobial activity observed. Furthermore, many compounds could not be identified and so these unknowns present further potential for novel bioactive compounds.
PubMed: 37970077
DOI: 10.1099/acmi.0.000629.v4 -
International Journal of Molecular... Oct 2023The co-culturing of microorganisms is a well-known strategy to study microbial interactions in the laboratory. This approach facilitates the identification of new...
The co-culturing of microorganisms is a well-known strategy to study microbial interactions in the laboratory. This approach facilitates the identification of new signals and molecules produced by one species that affects other species' behavior. In this work, we have studied the effects of the interaction of nine species (, , , , , , , , and ) with the predator bacteria , five of which (, , , , and ) induce mound formation of on complex media (Casitone Yeast extract (CYE) and Casitone tris (CTT); media on which does not form these aggregates under normal culture conditions. An in-depth study on - interactions (the strain producing the strongest effect) has allowed the identification of two siderophores produced by , demethylenenocardamine and nocardamine, responsible for this grouping effect over . Experiments using pure commercial nocardamine and different concentrations of FeSO show that iron depletion is responsible for the behavior of . Additionally, it was found that molecules, smaller than 3 kDa, produced by can induce the production of DK-xanthenes by .
Topics: Myxococcus; Myxococcus xanthus; Streptomyces; Microbial Interactions; Iron
PubMed: 37958645
DOI: 10.3390/ijms242115659 -
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 -
STAR Protocols Dec 2023Protein-protein interactions are foundational for many cellular processes. Such interactions are especially challenging to identify if they are transient or depend on...
Protein-protein interactions are foundational for many cellular processes. Such interactions are especially challenging to identify if they are transient or depend on environmental conditions. This protocol details steps to identify stable and transient protein interactomes in the bacterium Myxococcus xanthus using biotin ligase miniTurbo-based proximity labeling. We include instructions for optimizing the expression of control proteins, in vivo biotin labeling of bacteria grown on a surface or in suspension culture, enrichment of biotinylated proteins, and sample processing for proteomic analysis. For complete details on the use and execution of this protocol, please refer to Branon et al. (2018)..
Topics: Biotin; Myxococcus xanthus; Proteomics
PubMed: 37883223
DOI: 10.1016/j.xpro.2023.102657 -
Frontiers in Microbiology 2023Myxobacteria are widely distributed in various habitats of soil and oceanic sediment. However, it is unclear whether soil-dwelling myxobacteria tolerate a saline...
Myxobacteria are widely distributed in various habitats of soil and oceanic sediment. However, it is unclear whether soil-dwelling myxobacteria tolerate a saline environment. In this study, a salt-tolerant myxobacterium sp. strain MxC21 was isolated from forest soil with NaCl tolerance >2% concentration. Under 1% salt-contained condition, strain MxC21 could kill and consume bacteria prey and exhibited complex social behaviors such as S-motility, biofilm, and fruiting body formation but adopted an asocial living pattern with the presence of 1.5% NaCl. To investigate the genomic basis of stress tolerance, the complete genome of MxC21 was sequenced and analyzed. Strain MxC21 consists of a circular chromosome with a total length of 9.13 Mbp and a circular plasmid of 64.3 kb. Comparative genomic analysis revealed that the genomes of strain MxC21 and DK1622 share high genome synteny, while no endogenous plasmid was found in DK1622. Further analysis showed that approximately 21% of its coding genes from the genome of strain MxC21 are predominantly associated with signal transduction, transcriptional regulation, and protein folding involved in diverse niche adaptation such as salt tolerance, which enables social behavior such as gliding motility, sporulation, and predation. Meantime, a high number of genes are also found to be involved in defense against oxidative stress and production of antimicrobial compounds. All of these functional genes may be responsible for the potential salt-toleration. Otherwise, strain MxC21 is the second reported myxobacteria containing indigenous plasmid, while only a small proportion of genes was specific to the circular plasmid of strain MxC21, and most of them were annotated as hypothetical proteins, which may have a direct relationship with the habitat adaptation of strain MxC21 under saline environment. This study provides an inspiration of the adaptive evolution of salt-tolerant myxobacterium and facilitates a potential application in the improvement of saline soil in future.
PubMed: 37789850
DOI: 10.3389/fmicb.2023.1250602 -
MBio Oct 2023Type IVa pili (T4aP) are widespread bacterial cell surface structures with important functions in motility, surface adhesion, biofilm formation, and virulence. Different...
Type IVa pili (T4aP) are widespread bacterial cell surface structures with important functions in motility, surface adhesion, biofilm formation, and virulence. Different bacteria have adapted different piliation patterns. To address how these patterns are established, we focused on the bipolar localization of the T4aP machine in the model organism by studying the localization of the PilQ secretin, the first component of this machine that assembles at the poles. Based on experiments using a combination of fluorescence microscopy, biochemistry, and computational structural analysis, we propose that PilQ, and specifically its AMIN domains, binds septal and polar peptidoglycan, thereby enabling polar Tgl localization, which then stimulates PilQ multimerization in the outer membrane. We also propose that the presence and absence of AMIN domains in T4aP secretins contribute to the different piliation patterns across bacteria.
Topics: Fimbriae Proteins; Myxococcus xanthus; Fimbriae, Bacterial
PubMed: 37754549
DOI: 10.1128/mbio.01593-23 -
MSystems Oct 2023Understanding the processes behind bacterial biofilm formation, maintenance, and dispersal is essential for addressing their effects on health and ecology. Within these...
Understanding the processes behind bacterial biofilm formation, maintenance, and dispersal is essential for addressing their effects on health and ecology. Within these multicellular communities, various cues can trigger differentiation into distinct cell types, allowing cells to adapt to their specific local environment. The soil bacterium forms biofilms in response to starvation, marked by cells aggregating into mounds. Some aggregates persist as spore-filled fruiting bodies, while others disperse after initial formation for unknown reasons. Here, we use a combination of cell tracking analysis and computational simulations to identify behaviors at the cellular level that contribute to aggregate dispersal. Our results suggest that cells in aggregates actively determine whether to disperse or persist and undergo a transition to sporulation based on a self-produced cue related to the aggregate size. Identifying these cues is an important step in understanding and potentially manipulating bacterial cell-fate decisions.
Topics: Spores, Bacterial; Myxococcus xanthus; Biofilms; Cell Differentiation
PubMed: 37747885
DOI: 10.1128/msystems.00425-23