-
Frontiers in Microbiology 2023Adjusting motility patterns according to environmental cues is important for bacterial survival. , a bacterium moving on surfaces by gliding and twitching mechanisms,...
Adjusting motility patterns according to environmental cues is important for bacterial survival. , a bacterium moving on surfaces by gliding and twitching mechanisms, modulates the reversal frequency of its front-back polarity in response to mechanical cues like substrate stiffness and cell-cell contact. In this study, we propose that 's gliding machinery senses environmental mechanical cues during force generation and modulates cell reversal accordingly. To examine our hypothesis, we expand an existing mathematical model for periodic polarity reversal in , incorporating the experimental data on the intracellular dynamics of the gliding machinery and the interaction between the gliding machinery and a key polarity regulator. The model successfully reproduces the dependence of cell reversal frequency on substrate stiffness observed in gliding. We further propose reversal control networks between the gliding and twitching motility machineries to explain the opposite reversal responses observed in wild type cells that possess both motility mechanisms. These results provide testable predictions for future experimental investigations. In conclusion, our model suggests that the gliding machinery in can function as a mechanosensor, which transduces mechanical cues into a cell reversal signal.
PubMed: 38260904
DOI: 10.3389/fmicb.2023.1294631 -
BioRxiv : the Preprint Server For... Dec 2023Ecological context often modifies biotic interactions, yet effects of ecological history are poorly understood. In experiments with the bacterium , resource-level...
Ecological context often modifies biotic interactions, yet effects of ecological history are poorly understood. In experiments with the bacterium , resource-level histories of genotypes interacting during cooperative multicellular development were found to strongly regulate social fitness. Yet how developmental spore production responded to variation in resource-level histories between interactants differed greatly between cooperators and cheaters; relative-fitness advantages gained by cheating after high-resource growth were generally reduced or absent if one or both parties experienced low-resource growth. Low-resource growth also eliminated facultative exploitation in some pairwise mixes of cooperation-proficient natural isolates that occurs when both strains have grown under resource abundance. Our results contrast with previous studies in which cooperator fitness correlated positively with resource level and suggest that resource-level variation may be important in regulating whether exploitation of cooperators occurs in a natural context.
PubMed: 38168390
DOI: 10.1101/2023.12.14.571652 -
Frontiers in Microbiology 2023and represent a well-studied microbial predator-prey pair frequently examined in laboratory settings. While significant progress has been made in comprehending the...
and represent a well-studied microbial predator-prey pair frequently examined in laboratory settings. While significant progress has been made in comprehending the mechanisms governing predation, various aspects of the response and defensive mechanisms of as prey remain elusive. In this study, the MG1655 large-scale chromosome deletion library was screened, and a mutant designated as ME5012 was identified to possess significantly reduced susceptibility to predation by . Within the deleted region of ME5012 encompassing seven genes, the significance of and genes in driving the observed phenotype became apparent. Specifically, the deletion of resulted in a notable reduction in flagellum production in , contributing to a certain level of resistance against predation by . Meanwhile, the removal of in led to diminished inducibility of myxovirescin A production by , accompanied by a slight decrease in susceptibility to myxovirescin A. These findings shed light on the molecular mechanisms underlying the complex interaction between and in a predatory context.
PubMed: 38116529
DOI: 10.3389/fmicb.2023.1304874 -
Journal of Bacteriology Jan 2024The LPXTG protein-sorting signal, found in surface proteins of various Gram-positive pathogens, was the founding member of a growing panel of prokaryotic small...
The LPXTG protein-sorting signal, found in surface proteins of various Gram-positive pathogens, was the founding member of a growing panel of prokaryotic small C-terminal sorting domains. Sortase A cleaves LPXTG, exosortases (XrtA and XrtB) cleave the PEP-CTERM sorting signal, archaeosortase A cleaves PGF-CTERM, and rhombosortase cleaves GlyGly-CTERM domains. Four sorting signal domains without previously known processing proteases are the MYXO-CTERM, JDVT-CTERM, Synerg-CTERM, and CGP-CTERM domains. These exhibit the standard tripartite architecture of a short signature motif, a hydrophobic transmembrane segment, and an Arg-rich cluster. Each has an invariant cysteine in its signature motif. Computational evidence strongly suggests that each of these four Cys-containing sorting signals is processed, at least in part, by a cognate family of glutamic-type intramembrane endopeptidases related to the eukaryotic type II CAAX-processing protease Rce1. For the MYXO-CTERM sorting signals of different lineages, their sorting enzymes, called myxosortases, include MrtX (MXAN_2755 in ), MrtC, and MrtP, all with radically different N-terminal domains but with a conserved core. Related predicted sorting enzymes were also identified for JDVT-CTERM (MrtJ), Synerg-CTERM (MrtS), and CGP-CTERM (MrtA). This work establishes a major new family of protein-sorting housekeeping endopeptidases contributing to the surface attachment of proteins in prokaryotes. IMPORTANCE Homologs of the eukaryotic type II CAAX-box protease Rce1, a membrane-embedded endopeptidase found in yeast and human ER and involved in sorting proteins to their proper cellular locations, are abundant in prokaryotes but not well understood there. This bioinformatics paper identifies several subgroups of the family as cognate endopeptidases for four protein-sorting signals processed by previously unknown machinery. Sorting signals with newly identified processing enzymes include three novel ones, but also MYXO-CTERM, which had been the focus of previous experimental work in the model fruiting and gliding bacterium . The new findings will substantially improve our understanding of Cys-containing C-terminal protein-sorting signals and of protein trafficking generally in bacteria and archaea.
Topics: Humans; Cysteine; Protein Transport; Peptide Hydrolases; Membrane Proteins; Bacteria; Saccharomyces cerevisiae
PubMed: 38084967
DOI: 10.1128/jb.00173-23 -
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