Biology subjects

Bramkamp, M.

Publications and source records attributed to Bramkamp, M..

At least 19 recordsLinked to original sources

bioRxiv2026

A conserved oscillatory system that positions the divisome in Archaea

Precise placement of the cell division machinery is essential for cell division in most organisms, yet the mechanisms responsible for this process vary substantially across the domains of life. In Eukaryotes, cell division is primarily driven by ESCRT-based systems, while many Bacteria rely on the Min system to ensure accurate positioning of the division septum. By contrast, the mechanisms by which Archaea spatially regulate divisome assembly remain largely unknown. Here, we identify a three-protein system, which we term divisome positioning proteins A, B and C (DipA, DipB and DipC) that is essential for correct divisome positioning in Haloferax volcanii. Deletion of any dip gene results in mislocalization of cell division proteins and the formation of abundant minicells, similar to Min defects in bacteria. Furthermore, we show that all three Dip proteins undergo pole-to-pole oscillation, and that DipB and DipC assemble into ring-like structures at midcell. Biochemical analyses demonstrate that DipA is a membrane binding GTPase whose association with the membrane is disrupted by DipB. Notably, Dip homologues are widely conserved across diverse archaeal lineages that employ FtsZ-based division, indicating that the Dip system is a broadly distributed key regulator of FtsZ-based cell division in Archaea. Despite its striking functional similarities to the bacterial Min system, the Dip system is entirely unrelated at the sequence level, representing a compelling example of convergent evolution of oscillatory spatial regulators in distinct domains of life.

microbiology↗

bioRxiv2026

An SPFH Protein Couples Membrane Stress to Differentiation in Bacillus subtilis

Bacillus subtilis adapts to fluctuating environmental stress, such as membrane perturbation or alkaline conditions, using membrane-associated regulatory complexes. Here, we rename the previously termed pspA-ydjGHI operon to pspA-samGHI (for starvation and motility) to reflect its functional roles in membrane envelope stress signalling. The SamG-SamH membrane proteins recruit SamI, a cytosolic SPFH protein, which stabilizes focal membrane localization and recruitment of PspA, an ESCRT-III homolog. Under normal conditions, this system transiently assembles at the membrane, stabilizing it and allowing proper motility, secretion, and biofilm formation. Loss of SamI ({Delta}samI/{Delta}ydjI) leads to unbalanced SamG-SamH activity leading to a constitutive stress signalling, and global transcriptional changes reminiscent of starvation situations. This, in turn, blocks secretion of the matrix protein BslA, preventing biofilm formation, and reducing motility. Deletion of samH in combination with {Delta}samI restores biofilm formation, while {Delta}pspA mutants form biofilms normally, indicating that PspA is dispensable for the developmental phenotype. Our findings reveal that beside membrane integrity SamGHI coordinates transcriptional homeostasis and multicellular development through formation of a membrane integral stress sensor complex.

microbiology↗

bioRxiv2025

Equipositioning of Chromosomes in the Polyploid Archaeon Haloferax volcanii by HpaAB

Proper genome segregation is essential for all life forms, but in archaea, this process is less characterized as compared to bacteria, or eukarya. Archaea show considerable variability in chromosome and plasmid copy number, and organization. Stable maintenance of chromosomes and low-copy plasmids in organisms requires an active segregation system. Haloferax volcanii DS2 is a polyploid archaeon that contains a fragmented genome composed of a main chromosome, three secondary chromosomes, pHV1, pHV3 and pHV4, as well as a plasmid pHV2. Due to the high copy number of all replicons, genomic segregation in H. volcanii is typically considered random. However, we identified four two-gene operons encoding a ParA-like homologue and an uncharacterized protein. Here we characterized one of these systems, termed here HpaA (ParA-homolog) and HpaB, that is encoded on the secondary chromosome pHV3. HpaA, showing conserved ATPase walker motifs, is a ParA protein with a bacterial origin acquired via horizontal gene transfer. Mutation of key residues in HpaA alters its localization, and HpaA is necessary for proper spatial distribution of HpaB. HpaB, an archaeal protein capable of forming foci in the cytosol, is shown to function as a centromere-binding protein, thereby acting as a functional ParB homologue. qPCR data confirm that HpaB is crucial for maintaining the plasmid-to-chromosome ratio, as deletion of hpaB reduces pHV3 copy number. Single particle tracking suggests that absence of HpaB leads to an altered population distribution of HpaA, based on protein dynamics. Deletion of the genes hpaA and hpaB results in severe growth defects when cells are grown on xylose as a sole carbon source, in line with the location of the genes for the xylose degradation pathway on chromosome pHV3. We propose that H. volcanii has an active chromosome segregation system, essential for the "two-dimensional" segregation and equipositioning of its replicons. This function is crucial for ensuring stable replicon maintenance across the distinct cell morphologies of H. volcanii, which transition between rod-shaped and disc-shaped forms at different stages of growth.

microbiology↗

bioRxiv2025

Maternal transmission of a plastid structure enhances offspring fitness

Development in the sea has long been thought to be a nutritional gamble that disproportionately ends in starvation. Here, we unexpectedly show that components of plastids are incorporated into sea urchin eggs and that these, in turn, benefit developmental fitness. We find chromoplast-derived carotenoid crystals and chromoplast-specific metabolites inside of sea urchin eggs. The light-dependent activity of these chromoplast components influence the subsequent abundance of phytohormones that, in turn, regulate the use of energetic lipids that promote development and survival. Offspring that benefit from these chromoplast components are predicted to disperse further, over larger geographic areas, and use a wider range of currents, including those that cross ocean basins. Data presented here challenge the long-held assumption that components of non-metazoan organelles are unable to enter the germline and be passed between generations. We hypothesize that sea urchins manipulate plastids solely for their self-interest by a process that we term machioplasty, with the result of this process being a novel and adaptive form of maternal provisioning. SIGNIFICANCEMaking a fertilizable egg is a complex and carefully regulated process. One long-held assumption is that any component of non-animal organelles are unable to cross the evolutionary valley between non-reproductive and reproductive cells. Here, we unexpectedly show that components of plastids are incorporated into sea urchin eggs and that these, in turn, benefit developmental fitness. Offspring benefit from these plastid components by developing more quickly into larvae and having higher survival due to ability to use phytohormones that influence energetic lipids. This allows offspring to use a wider range of ocean currents, including those that cross entire basins. This challenge the long-held assumption that components of non-metazoan organelles are unable to be passed between generations.

developmental biology↗

bioRxiv2025

Robust antibiotic sensitization of pathogenic Pseudomonas aeruginosa via negative hysteresis in the cell envelope

Antibiotic combination in time and space is a key strategy to combat antimicrobial resistance. The success of such treatment designs requires their robust efficacy across treatment conditions and a pathogens genomic diversity. This study found that an initial treatment with a {beta}-lactam antibiotic causes robust cellular sensitization towards an aminoglycoside antibiotic across the high-risk human pathogen Pseudomonas aeruginosa, including resistant strains. This phenomenon of cellular sensitization, termed negative hysteresis, is modulated by the Cpx envelope stress response system and linked to membrane stress during growth. The increase in efficacy is achieved through a {beta}-lactam induced elevated cellular uptake of the subsequently administered aminoglycoside. Negative hysteresis and the Cpx system are linked in several cases to the expression of synergistic drug interactions, thus enhancing efficacy of antibiotic combinations. Overall, our study identifies the phenomenon of negative hysteresis as a robustly inducible phenotype and thus a unique focus for optimizing antimicrobial therapy.

evolutionary biology↗

bioRxiv2025

The ParA-like ATPase PldP influences the TatA dynamics in Corynebacterium glutamicum

In bacterial cells, precise localization of protein complexes is achieved by unique positioning systems. One of the examples of such positioning systems is the ParAB-parS which is responsible for plasmid and chromosome segregation. In Corynebacterium glutamicum, a parAB deletion results in cell division and growth defects, while deletion of an orphan ParA-like protein pldP results only in a moderate cell division phenotype. Having confirmed a basal ATPase activity of PldP, we aimed to explore if the {Delta}pldP-related phenotype could be a consequence of the mislocalized secreted proteins, as the loss of extracellular proteins involved in cell wall metabolism results in a similar phenotype characterized by disrupted separation of daughter cells. Putative peptidoglycan hydrolase Rv2525c from Mycobacterium tuberculosis and Rv2525c-like glycoside hydrolase-like domain-containing protein Cg0955 from C. glutamicum were previously shown to be transported outside of the cell by twin-arginine protein translocation machinery (Tat). Here, we found that although the deletion of pldP did not lead to the altered secretion of the putative hydrolase Cg0955 by the Tat system, it resulted in the reduction of the Tat dynamics. Our findings highlight the interplay between the ParA-like ATPase PldP and the Tat translocon and contribute to the studies of ParA-like proteins being essential in positioning various cargos in the bacterial cells. ImportancePrecise spatio-temporal localization of protein complexes within a bacterial cell is essential for the survival and proliferation of bacteria. ParA-like ATPases play a crucial role in protein positioning, as well as chromosome and plasmid segregation. Here, we characterize a novel ParA-like ATPase PldP in Corynebacterium glutamicum, a model organism for the cell biology of Mycobacteriales and a biotechnological workhorse. Deletion of pldP results in the cell division phenotypes and impacts the intracellular dynamics of TatA, a component of the twin-arginine protein transport. We suggest that the mislocalization of the Tat-secreted putative peptidoglycan hydrolase caused by the indirect influence of pldP deletion might account for the observed cell separation defect.

microbiology↗

bioRxiv2025

Membrane-binding of the bacterial dynamin-like protein DynA is essential for effective phage defence

Bacterial dynamin-like proteins are large GTPases that play crucial roles in membrane dynamics. DynA in B. subtilis, a two-headed bacterial dynamin-like protein, possesses membrane-binding and tethering functions in trans. The formation of large DynA clusters on membranes in response to pore-forming antibiotics and phages demonstrates its potential role in maintaining membrane integrity under various environmental stresses. In this study, we identified the membrane-binding site of B. subtilis DynA within the D1 domain of the protein that includes positively charged lysine residues K360 and K367, as well as hydrophobic phenylalanine residues F363, F364, and F365. For experimental validation, recombinant proteins with mutations in the lysine or phenylalanine residues were produced and used in liposome binding assays. Non-conservative mutations lead to a complete loss of DynAs membrane-binding capability. In vivo data showed that the membrane-binding mutants exhibit significantly increased susceptibility to phage infection compared to wild-type strains, further emphasizing the importance of DynAs membrane interaction in conferring phage resistance. Our findings bridge the gap between the structural characteristics of DynA and its functional implications in maintaining membrane integrity and mediating phage resistance.

microbiology↗

bioRxiv2024

Assembly of a functional neuronal circuit in embryos of an ancestral metazoan is influenced by environmental signals including the microbiome

Understanding how neural populations evolve to give rise to behavior is a major goal in neuroscience. However, the complexity of the nervous system in most invertebrates and vertebrates complicates the deciphering of underlying fundamental processes. Here, we explore the self-assembly of neural circuits in Hydra, an organism with a simple nervous system but no centralized information processing, to improve the understanding of nervous system evolution. The N4 neuronal circuit in embryos develops through activity-driven self-assembly, where neurons in distinct regions increase connectivity and synchronization. Gap junctions and vesicle-mediated communication between neuronal and non-neuronal cells drive rapid assembly, with the embryos prospective oral region exhibiting the highest neuronal density. An artificial electrical circuit-based model demonstrates dynamic increases in synchronization over time, along with predictions for selective dynamic adaptions of connections. Environmental factors, like temperature and an absent microbiome, modify neural architecture, suggesting the existence of a certain plasticity in neural development. We propose that these fundamental features originated in the last common bilaterian ancestor, supporting the hypothesis that the basic architecture of the nervous system is universal.

neuroscience↗

bioRxiv2024

Mechanistic Insights into MinD Regulation and Pattern Formation in Bacillus subtilis

Bacteria precisely regulate the place and timing of their cell division. One of the best-understood systems for division site selection is the Min system in Escherichia coli. In E. coli, the Min system displays remarkable pole-to-pole oscillation, creating a time-averaged minimum at the cells geometric center, which marks the future division site. Interestingly, the Gram-positive model species Bacillus subtilis also encodes homologous proteins: the cell division inhibitor MinC and the Walker-ATPase MinD. However, B. subtilis lacks the activating protein MinE, which is essential for Min dynamics in E. coli. We have shown before that the B. subtilis Min system is highly dynamic and quickly relocalizes to active sites of division. This raised questions about how Min protein dynamics are regulated on a molecular level in B. subtilis. Here, we show with a combination of in vitro experiments and in vivo single-molecule imaging that the ATPase activity of B. subtilis MinD is activated by membrane binding. Additionally, both monomeric and dimeric MinD bind to the membrane, and binding of ATP to MinD is a prerequisite for fast membrane detachment. Single-molecule localization microscopy data confirm membrane binding of monomeric MinD variants. However, only wild type MinD enriches at cell poles and sites of ongoing division, likely due to interaction with MinJ. Monomeric MinD variants and locked dimers remain distributed along the membrane and lack the characteristic pattern formation. Single-molecule tracking data further support that MinD has a freely diffusive population, which is increased in the monomeric variants and a membrane binding defective mutant. Thus, MinD dynamics in B. subtilis under the tested conditions do not require any unknown protein component and can be fully explained by MinDs binding and unbinding kinetics with the membrane. The spatial organization of MinD relies on the short-lived temporal residence of MinD dimers at the membrane.

microbiology↗

bioRxiv2023

Deletion of SMC renders FtsK essential in Corynebacterium glutamicum

Structural maintenance of chromosomes (SMC) are ubiquitously distributed proteins involved in chromosome organization. Deletion of smc causes severe growth phenotypes in many organisms. Surprisingly, smc can be deleted in Corynebacterium glutamicum, a member of the Actinomycetota phylum, without any apparent growth phenotype. Earlier work has shown that SMC in C. glutamicum is loaded in a ParB-dependent fashion to the chromosome and functions in replichore cohesion. The unexpected absence of a growth phenotype in the smc mutant prompted us to screen for unknown synthetic interactions within C. glutamicum. Therefore, we generated a high-density Tn-5 library based on wild-type and smc-deleted C. glutamicum strains. The transposon sequencing (Tn-seq) data revealed that the DNA-translocase FtsK is essential in a smc deletion strain. FtsK localized to the septa and cell poles in wild type cells, however deletion of smc resulted in a decreased polar FtsK localization. Single-particle tracking analysis further suggests that prolonged FtsK complex activity is both required and sufficient to make up for the absence of SMC, thus achieving efficient chromosome segregation in C. glutamicum. Further, single molecule dynamics of FtsK is influenced, albeit indirectly, by DNA-loaded SMC. Deletion of ParB results in an increased of both SMC and FtsK mobility. While the first change agrees with previous data that show how ParB is essential for SMC loading on DNA, the latter suggests that FtsK mobility is affected in cells with defects in chromosome organization. Based on our data we propose a simple, yet efficient mechanism for efficient DNA segregation in C. glutamicum, even in absence of SMC proteins. ImportanceFaithful DNA segregation is of fundamental importance for life. Bacteria have efficient systems to coordinate chromosome compaction, DNA segregation and cell division. A key factor in DNA compaction is the SMC-complex that is found to be essential in many bacteria. In members of the Actinomycetota smc is dispensable, but the reason for this was unclear. We show here that the divisome associated DNA-pump FtsK can compensate SMC loss and the subsequent loss in correct chromosome organization. In cells with distorted chromosomes, FtsK functions for an extended period of time at the septum, until chromosomes are segregated.

microbiology↗

bioRxiv2023

Effects of benzothiazinone and ethambutol on the integrity of the corynebacterial cell envelope

The mycomembrane (MM) is a hydrophobic layer formed by mycolic acids covering the surface of Mycobacteria and related species. This group includes important pathogens such as Mycobacterium tuberculosis, Corynebacterium diphtheriae, but also the biotechnologically important strain Corynebacterium glutamicum. The MM contributes to the impermeability of the cell envelope and thereby also protects bacteria from antibiotics. This makes biosynthesis of the MM an attractive target for antibiotic intervention. The first line anti-tuberculosis drug ethambutol (EMB) interferes with the synthesis of the arabinogalactan (AG), which is a structural scaffold for covalently attached mycolic acids that form the inner leaflet of the MM. Similarly, the new drug candidate, benzothiazinone 043 (BTZ) affects the synthesis of the AG component of the cell wall. We previously showed that C. glutamicum cells treated with a sublethal concentration of EMB lose the integrity of the MM. In this study we examined the effects of a sublethal concentration of BTZ. Our work shows that 1 {micro}g ml-1 BTZ efficiently blocks the apical growth machinery and reduces cell proliferation, however the integrity of the MM is largely preserved and the effects of {beta}-lactam antibiotics are only additive, not synergistic. Transmission electron microscopy (TEM) analysis revealed a distinct middle layer in the septum of control cells considered to be the inner leaflet of the MM covalently attached to the AG. It functions as a greasy slide for the lateral flow of mycolic acids in the outer leaflet. This layer was not detectable in the septa of BTZ or EMB treated cells, which suggests that the greasy slide is impaired and the confluency of the MM is thereby reduced. In addition, we observed that EMB treated cells have a thicker and less electron dense peptidoglycan (PG) layer consistent with the report that EMB also inhibits the glutamate racemase MurI. We conclude that EMB and BTZ have distinct differences in their modes of action. While EMB and BTZ both effectively block elongation growth, BTZ also strongly reduces septal cell wall synthesis. This renders BTZ treated cells likely more tolerant to antibiotics that act on growing bacteria.

microbiology↗

bioRxiv2023

Four novel Caudoviricetes bacteriophages isolated from Baltic Sea water infect colonizers of Aurelia aurita

The moon jellyfish Aurelia aurita is associated with a highly diverse microbiota changing with provenance, tissue, and life stage. While the crucial relevance of bacteria to host fitness is well known, bacteriophages have often been neglected. Here, we aimed to isolate lytic phages targeting bacteria that are part of the A. aurita-associated microbiota. Four phages (Pseudomonas phage BSwM KMM1, Citrobacter phages BSwM KMM2- BSwM KMM4) were isolated from the Baltic Sea water column and characterized. Phages KMM2/3/4 infected representatives of Citrobacter, Shigella, and Escherichia (Enterobacteriaceae), whereas KMM1 showed a remarkably broad host range, infecting Gram- negative Pseudomonas as well as Gram-positive Staphylococcus. All phages showed short latent periods (around 30 min), large burst sizes (mean of 128 pfu/mL), and high efficiency of plating (EOP > 0.5), demonstrating decent virulence, efficiency, and infectivity. Transmission electron microscopy and viral genome analysis revealed that all phages are novel species and belong to the tailed, linear double- stranded DNA phage families Siphovirus (KMM3) and Myovirus (KMM1/2/4), with genome sizes between 50 - 138 kbp. Those isolates now allow manipulation of the A. aurita-associated microbiota and will provide new insights into phage impact on the multicellular host.

microbiology↗

bioRxiv2022

A novel nuclease is the executing part of a bacterial plasmid defense system

Cells are continuously facing the risk of taking up foreign DNA that can compromise genomic and cellular integrity. Therefore, bacteria are in a constant arms race with mobile genetic elements such as phages, transposons and plasmids. They have developed several active strategies against invading DNA molecules that can be seen as a bacterial innate immune system. Anti-phage systems are usually organized in defense islands and can consist of restriction-modification (R-M) systems, CRISPR-Cas, and abortive infection (Abi) systems. Despite recent advances in the field, much less is known about plasmid defense systems. We have recently identified the MksBEFG system in Corynebacterium glutamicum as a novel plasmid defense system which comprises homologues of the condensin system MukFEB. Here, we investigated the molecular arrangement of the MksBEFG complex. Importantly, we identified MksG as a novel nuclease that degrades plasmid DNA and is, thus, the executing part of the system. The crystal structure of MksG revealed a dimeric assembly through its DUF2220 C-terminal domains. This domain is homologous to the TOPRIM domain of the topoisomerase II family of enzymes and contains the corresponding divalent ion binding site that is essential for DNA cleavage in topoisomerases, explaining the in vitro nuclease activity of MksG. We further show that the MksBEF subunits exhibit an ATPase cycle similar to MukBEF in vitro and we reason that this reaction cycle, in combination with the nuclease activity provided by MksG, allows for processive degradation of invading plasmids. Super-resolution localization microscopy revealed that the Mks system is spatially regulated via to the polar scaffold protein DivIVA. Introduction of plasmids increases the diffusion rate and alters the localization of MksG, indicating an activation of the system in vivo.

microbiology↗

bioRxiv2022

Bacteroides muris sp. nov. isolated from the cecum of wild-derived house mice

Two bacterial strains, KH365_2T and KH569_7, were isolated from the cecum contents of wild-derived house mice. The strains were characterized as Gram-negative, rod-shaped, strictly anaerobic, and non-motile. Phylogenetic analysis based on 16S rRNA gene sequences revealed that both strains were most closely related to Bacteroides uniformis ATCC 8492T. Whole genome sequences of KH365_2T and KH569_7 strains have a DNA G+C content of 46.02% and 46.03% mol, respectively. Most morphological and biochemical characteristics did not differ between the newly isolated strains and classified Bacteroides strains. However, the average nucleotide identity (ANI) and dDNA-DNA hybridization (dDDH) values clearly distinguished the two strains from described members of the genus Bacteroides. Here, we present the phylogeny, morphology, and physiology of a novel species of the genus Bacteroides and propose the name Bacteroides muris sp. nov., with KH365_2T (DSM XXX = CCUG XXX) as type strain.

microbiology↗

bioRxiv2021

A bacterial dynamin-like protein confers a novel phage resistance strategy on the population level in Bacillus subtilis

Bacillus subtilis DynA is a member of the dynamin superfamily, involved in membrane remodeling processes. DynA was shown to catalyze full membrane fusion and it plays a role in membrane surveillance against antibiotics. We show here that DynA also provides a novel resistance mechanism against phage infection. Cells lacking DynA are efficiently lysed after phage infection and virus replication. DynA does not prevent phage infection and replication in individual cells, but significantly delays host cell lysis, thereby slowing down the release of phage progeny from the host cells. During the process, DynA forms large, almost immobile clusters on the cell membrane that seem to support membrane integrity. Single molecule tracking revealed a shift of freely diffusive molecules within the cytosol towards extended, confined motion at the cell membrane following phage induction. Thus, the bacterial dynamins are the first anti-phage system reported to delay host cell lysis and the last line of defense of a multilayered antiviral defense. DynA is therefore providing protective effects on the population, but not on single cell level.

microbiology↗

bioRxiv2021

The CTPase activity of ParB acts as a timing mechanism to control the dynamics and function of prokaryotic DNA partition complexes

DNA partitioning CTPases of the ParB family mediate the segregation of bacterial chromosomes and low-copy number plasmids. They act as DNA-sliding clamps that are loaded at parS motifs in the centromeric region of target DNA molecules and then spread laterally to form large nucleoprotein complexes that serve as docking points for the DNA segregation machinery. Here, we identify conformational changes that underlie the CTP- and parS-dependent closure of ParB clamps. Moreover, we solve crystal structures of ParB in the pre- and post-hydrolysis state and provide insights into the catalytic mechanism underlying nucleotide hydrolysis. The characterization of CTPase-deficient ParB variants reveals that CTP hydrolysis serves as a timing mechanism to control the sliding time of ParB. Hyperstable clamps are trapped on the DNA, leading to excessing spreading and severe chromosome segregation defects in vivo. These findings clarify the role of the ParB CTPase cycle in partition complex dynamics and function and thus complete our understanding of this prototypic CTP-dependent molecular switch.

microbiology↗

bioRxiv2020

Single-cell growth inference of Corynebacterium glutamicum reveals asymptotically linear growth

Regulation of growth and cell size is crucial for the optimization of bacterial cellular function. So far, single bacterial cells have been found to grow exponentially, which implies the need for tight regulation to maintain cell size homeostasis. Here, we characterize the growth behavior of the apically growing bacterium Corynebacterium glutamicum using a novel broadly applicable inference method for single-cell growth dynamics. Using this approach, we find that C. glutamicum exhibits asymptotically linear single-cell growth. To explain this growth mode, we model elongation as being rate-limited by the apical growth mechanism. Our model accurately reproduces the inferred cell growth dynamics and is validated with elongation measurements on a transglycosylase deficient{Delta} rodA mutant. Finally, with simulations we show that the distribution of cell lengths is narrower for linear than exponential growth, suggesting that this asymptotically linear growth mode can act as a substitute for tight division length and division symmetry regulation.

microbiology↗

bioRxiv2020

Dynamics of the Bacillus subtilis Min system

Division site selection is a vital process to ensure generation of viable offspring. In many rod-shaped bacteria a dynamic protein system, termed the Min system, acts as a central regulator of division site placement. The Min system is best studied in Escherichia coli where it shows a remarkable oscillation from pole to pole with a time-averaged density minimum at midcell. Several components of the Min system are conserved in the Gram-positive model organism Bacillus subtilis. However, in B. subtilis it is believed that the system forms a stationary bipolar gradient from the cell poles to midcell. Here, we show that the Min system of B. subtilis localizes dynamically to active sites of division, often organized in clusters. We provide physical modelling using measured diffusion constants that describe the observed enrichment of the Min system at the septum. Modelling suggests that the observed localization pattern of Min proteins corresponds to a dynamic equilibrium state. Our data provide evidence for the importance of ongoing septation for the Min dynamics, consistent with a major role of the Min system to control active division sites, but not cell pole areas.

microbiology↗