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Journal of Bacteriology Sep 2023The regulation of biofilm and motile states as alternate bacterial lifestyles has been studied extensively in flagellated bacteria, where the second messenger...
The regulation of biofilm and motile states as alternate bacterial lifestyles has been studied extensively in flagellated bacteria, where the second messenger cyclic-di-GMP (cdG) plays a crucial role. However, much less is known about the mechanisms of such regulation in motile bacteria without flagella. The bacterial type IV pilus (T4P) serves as a motility apparatus that enables to move on solid surfaces. PilB, the T4P assembly ATPase, is, therefore, required for T4P-dependent motility in . Interestingly, T4P is also involved in the regulation of exopolysaccharide as the biofilm matrix material in this bacterium. A newly discovered cdG-binding domain, MshE, is conserved in the N-terminus of PilB (PilB) in and other bacteria. This suggests that cdG may bind to PilB to control the respective outputs that regulate biofilm development and T4P-powered motility. In this study, we aimed to validate PilB as a cdG effector protein. We performed a systematic mutational analysis of its cdG-binding domain to investigate its relationship with motility, piliation, and biofilm formation. Excluding those resulting in low levels of PilB protein, all other substitution mutations in PilB resulted in mutants with distinct and differential phenotypes in piliation and biofilm levels in . This suggests that the PilB domain plays dual roles in modulating motility and biofilm levels, and these two functions of PilB can be dependent on and independent of each other in . IMPORTANCE The regulation of motility and biofilm by cyclic-di-GMP in flagellated bacteria has been extensively investigated. However, our knowledge regarding this regulation in motile bacteria without flagella remains limited. Here, we aimed to address this gap by investigating a non-flagellated bacterium with motility powered by bacterial type-IV pilus (T4P). Previous studies hinted at the possibility of PilB, the T4P assembly ATPase, serving as a cyclic-di-GMP effector involved in regulating both motility and biofilm. Our findings strongly support the hypothesis that PilB directly interacts with cyclic-di-GMP to act as a potential switch to promote biofilm formation or T4P-dependent motility. These results shed light on the bifurcation of PilB functions and its pivotal role in coordinating biofilm formation and T4P-mediated motility.
Topics: Myxococcus xanthus; Cyclic GMP; Adenosine Triphosphatases; Biofilms
PubMed: 37695853
DOI: 10.1128/jb.00221-23 -
Microbiology (Reading, England) Jul 2023Myxobacteria are social microbial predators that use cell-cell contacts to identify bacterial or fungal prey and to differentiate kin relatives to initiate cellular... (Review)
Review
Myxobacteria are social microbial predators that use cell-cell contacts to identify bacterial or fungal prey and to differentiate kin relatives to initiate cellular responses. For prey killing, they assemble Tad-like and type III-like secretion systems at contact sites. For kin discrimination (KD), they assemble outer membrane exchange complexes composed of the TraA and TraB receptors at contacts sites. A type VI secretion system and Rhs proteins also mediate KD. Following cellular recognition, these systems deliver appropriate effectors into target cells. For prey, this leads to cell death and lysis for nutrient consumption by myxobacteria. In KD, a panel of effectors are delivered, and if adjacent cells are clonal cells, resistance ensues because they express a cognate panel of immunity factors; while nonkin lack complete immunity and are intoxicated. This review compares and contrasts recent findings from these systems in myxobacteria.
Topics: Animals; Myxococcales; Predatory Behavior; Myxococcus xanthus; Bacterial Proteins
PubMed: 37494115
DOI: 10.1099/mic.0.001372 -
FEMS Microbiology Letters Jan 2023Polyphosphate kinase 1 (Ppk1) generates polyphosphates (polyPs) by catalyzing phosphate transfer from ATP. In the presence of ATP, Myxococcus xanthus Ppk1 showed the...
Polyphosphate kinase 1 (Ppk1) generates polyphosphates (polyPs) by catalyzing phosphate transfer from ATP. In the presence of ATP, Myxococcus xanthus Ppk1 showed the highest activity with polyP60-70 but also showed high activity with orthophosphate and pyrophosphate. Ppk1 synthesizes long-chain polyPs with >1 000 phosphate residues from orthophosphate or pyrophosphate present in high concentrations, suggesting that in M. xanthus, Ppk1 uses intracellular ortho/pyrophosphate as an initial primer for polyP production. During M. xanthus starvation-induced development, the specific activity of Ppk1 peaked at 12 h (300-800 nmol/min/mg) and then gradually decreased. The polyP concentration was highest during mound formation (45 nmol phosphate/mg protein); then, the level of long-chain polyPs decreased and that of short-chain polyPs increased during fruiting body and spore formation. Myxococcus xanthus expresses two exopolyphosphatases, Ppx1 and Ppx2, which mainly degrade short- and long-chain polyPs, respectively, both of which were highest in vegetative cells and were detected during starvation, which may account for the degradation of polyPs. Thus, polyPs synthesized by Ppk1 early in starvation-induced development could be degraded by exopolyphosphatases and may also be used as substrates by polyP:AMP phosphotransferases and polyphosphate/ATP-NAD kinases to generate ADP and NADP+, respectively.
Topics: Polyphosphates; Diphosphates; Myxococcus xanthus; Adenosine Triphosphate
PubMed: 36731866
DOI: 10.1093/femsle/fnad007 -
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 -
Journal of the American Chemical Society Aug 2023The genomes of myxobacteria harbor a variety of biosynthetic gene clusters encoding numerous secondary metabolites, including ribosomally synthesized and...
The genomes of myxobacteria harbor a variety of biosynthetic gene clusters encoding numerous secondary metabolites, including ribosomally synthesized and post-translationally modified peptides (RiPPs) with diverse chemical structures and biological activities. However, the biosynthetic potential of RiPPs from myxobacteria remains barely explored. Herein, we report a novel myxobacteria lanthipeptide myxococin identified from . Myxococins represent the first example of lanthipeptides, of which the characteristic multiple thioether rings are installed by employing a Class II lanthipeptide synthetase MfuM and a Class I lanthipeptide cyclase MfuC in a cascaded way. Unprecedentedly, we biochemically characterized the first M61 family aminopeptidase MfuP involved in RiPP biosynthesis, demonstrating that MfuP showed the activity of an endopeptidase activity. MfuP is leader-independent but strictly selective for the multibridge structure of myxococin A and responsible for unwrapping two rings via amide bond hydrolysis, yielding myxococin B. Furthermore, the X-ray crystal structure of MfuP and structural analysis, including active-site mutations, are reported. Finally, myxococins are evaluated to exhibit anti-inflammatory activity in lipopolysaccharide-induced macrophages without detectable cytotoxicity.
Topics: Myxococcales; Peptides; Protein Processing, Post-Translational
PubMed: 37466996
DOI: 10.1021/jacs.3c06014 -
Biochimica Et Biophysica Acta. Proteins... Aug 2021Myxococcus xanthus possesses two exopolyphosphatases, mxPpx1 and mxPpx2, which belong to the family of Ppx/GppA phosphatases; however, their catalytic properties have...
Myxococcus xanthus possesses two exopolyphosphatases, mxPpx1 and mxPpx2, which belong to the family of Ppx/GppA phosphatases; however, their catalytic properties have not been described. mxPpx1 and mxPpx2 contain 311 and 505 amino acid residues, respectively; mxPpx2 has an additional C-terminal region, which corresponds to the metal-dependent HDc phosphohydrolase domain. mxPpx1 mainly hydrolyzed short-chain polyPs (polyP and polyP), whereas mxPpx2 preferred long-chain polyP and polyP. mxPpx2 was activated by 25-50 mM KCl, but mxPpx1 did not significantly depend on K. In addition, mxPpx1 and mxPpx2 showed weak hydrolysis of ATP and GTP in the absence of K, and mxPpx2 could also hydrolyze guanosine pentaphosphate (pppGpp) in the presence of K. The exopolyphosphatase activity of mxPpx1 toward polyP was inhibited by polyP and that of mxPpx2 toward polyP and polyP, by pyrophosphate. To clarify the function of the mxPpx2 C-terminal domain, it was fused to mxPpx1 (mxPpx1-2C) and deleted from mxPpx2 (mxPpx2∆C). Compared to wild-type mxPpx2, mxPpx2∆C had significantly reduced exopolyphosphatase activity toward long-chain polyPs (by 90%), whereas that toward polyP and polyP was much less affected; furthermore, the phosphohydrolase activity toward pppGpp, ATP, and GTP was also decreased (by 30-75%). In contrast, mxPpx1-2C had increased hydrolytic activity compared to mxPpx1. Furthermore, mxPpx2∆C lost the requirement for K characteristic for the wild-type enzyme, whereas mxPpx1-2C acquired it. These results suggest that the C-terminal domain of mxPpx2 is necessary for its maximum hydrolytic activity, especially toward long-chain polyPs, and defines mxPpx2 dependency on K for activation.
Topics: Acid Anhydride Hydrolases; Bacterial Proteins; Guanosine Pentaphosphate; Hydrolysis; Kinetics; Myxococcus xanthus; Phosphoric Monoester Hydrolases; Substrate Specificity
PubMed: 33857634
DOI: 10.1016/j.bbapap.2021.140660 -
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 -
International Journal of Systematic and... Sep 2020The International Committee on Systematics of Prokaryotes has formally made final decisions, taking into account the conclusions of the Judicial Commission, on three...
The International Committee on Systematics of Prokaryotes has formally made final decisions, taking into account the conclusions of the Judicial Commission, on three pending Requests for an Opinion, thereby allowing the corresponding Opinions to be issued. According to Opinion 100, the request for the recognition of strain A1-86 (=DSM 17629=NCIMB 14373) as the neotype strain of (Hauduroy 1937) Prévot 1938 (Approved Lists 1980) is denied, ruling that a neotype does not need to be designated for because strain VPI 0990 (=ATCC 33656=CIP 105953) is considered to be a duplicate isolate of the same strain as VPI 0989 (=ATCC 25578) and may serve as its nomenclatural type. Opinion 101 approves the request that strain ATCC 25946 (=DSM 14877) serves as the type strain of instead of strain ATCC 25944, formally correcting the Approved Lists of Bacterial Names. Opinion 102 concludes that strain Cc m8 (=DSM 14697=CIP 109128=JCM 12621) is an established neotype strain for the species , replacing the designated type strain Windsor M271, and that strain Mx s8 (=DSM 14675=JCM 12634) is an established neotype strain for the species , replacing the designated type strain Windsor M78, with some additional considerations about the nature of the type material replaced and about the name () .
Topics: Eubacterium; Myxococcales; Myxococcus; Phylogeny
PubMed: 32812861
DOI: 10.1099/ijsem.0.004390 -
Organic Letters Aug 2021The alkaloid physostigmine is an approved anticholinergic drug and an important lead structure for the development of novel therapeutics. Using a complementary approach...
The alkaloid physostigmine is an approved anticholinergic drug and an important lead structure for the development of novel therapeutics. Using a complementary approach that merged chemical synthesis with pathway refactoring, we produced a series of physostigmine analogues with altered specificity and toxicity profiles in the heterologous host . The compounds that were generated by applying a simple feeding strategy include the promising drug candidate phenserine, which was previously accessible only by total synthesis.
Topics: Molecular Structure; Myxococcus xanthus; Physostigmine
PubMed: 34355569
DOI: 10.1021/acs.orglett.1c02374 -
Current Opinion in Microbiology Jun 2024Myxococcus relies on motility to efficiently invade and predate a prey colony. Upon contact with prey, Myxococcus temporarily halts its motility and initiates prey cell... (Review)
Review
Myxococcus relies on motility to efficiently invade and predate a prey colony. Upon contact with prey, Myxococcus temporarily halts its motility and initiates prey cell lysis, which involves two contact-dependent predatory machineries, the Kil system and the needleless T3SS*. Predatory cells grow as they invade and feed on prey cells. When dividing, Myxococcus cells systematically pause their movements before division. This highlights a high level of co-ordination between motility and contact-dependent killing but also with cell division. In this review, we give an overview of the different nanomachines used by Myxococcus to move on surfaces, kill by contact, and divide, and we discuss the potential regulatory mechanisms at play during these different processes.
PubMed: 38843560
DOI: 10.1016/j.mib.2024.102492