Abstract. Faithful DNA segregation in bacteria relies on ParABS systems, in which ParB assembles into condensates at centromere-like parS sites, while the

Structural maintenance of chromosomes (SMC) complexes are conserved ATP-driven machines that organize, compact, and segregate genomes in all domains of life. Despite variation in subunit composition and regulation, all SMC complexes share a core structure and mechanism of action. Bacteria possess two major classes of SMC complexes, SMC-ScpAB and MukBEF, which function in chromosome compaction and segregation. In addition, some bacteria contain other SMC complexes or SMC-like systems such as MksBEF, Wadjet, RecN, and SbcC, each with specialized functions. Bacterial SMC complexes coordinate genome maintenance, DNA replication, DNA repair, plasmid defense, and cell physiology. In this review, we discuss the structure and function of these bacterial SMC complexes, highlighting the shared characteristics and unique strategies employed by each.

Bacterial genomes often include extrachromosomal replicons, ranging from small plasmids to chromosome-scale replicons. Here, Czarnecki et al. analyse more than 40,000 complete bacterial genomes and sh...

Properties of biomolecules; Epigenetics; Microbial genomics; Transcriptomics

Plasmids are extrachromosomal DNA molecules that spread by horizontal transfer and shape bacterial evolution. Plasmids are typically present at mul...

Bacteria must distinguish phage attack from normal homeostatic processes, yet the danger signals that trigger many defence systems remain unknown. Here, we show that a PUA-Calcineurin-CE-HAD module from Escherichia coli ECOR28 confers broad anti-phage protection by binding Dam-methylated deoxyadenosine monophosphate (m6-dAMP) generated during phage-induced chromosome degradation. Ligand binding converts a preassembled PUA-Calcineurin-CE hexamer loaded with six HAD phosphatases into a polymerising filament. The filament acts as a high-flux dNTP sink through a two-enzyme cascade: HAD first dephosphorylates dATP to dADP, and Calcineurin-CE then converts dADP to dAMP. dNTP collapse halts phage replication and enforces abortive infection. Multiple mobile-element DNA mimic proteins block filament assembly, revealing a direct phage counter-defence. More broadly, our findings extend a conserved, cross-kingdom paradigm of immune filament assembly to nucleotide-depletion antiviral defence and suggest modified-nucleotide sensing by related PUA-Calcineurin-CE modules as a widespread, underappreciated bacterial strategy. ### Competing Interest Statement The authors have declared no competing interest. NIHR Southampton Biomedical Research Centre, https://ror.org/01qqpzg67, Postdoctoral Bridging Fellowship F.L.N. is supported by a Wessex Health Partners (WHP) and National Institute for Health and Care Research Wessex Experimental Medicine Network (NIHR WEMN), Seed fund National Institutes of Health, GM145888, U24 GM129539) Maloris Foundation Memorial Sloan Kettering Cancer Center, P30-CA008748 Simons Foundation, SF349247 New York State Assembly

DNA methylation is a widespread phenomenon in bacteria that can regulate gene expression, although the mechanisms underlying this epigenetic regulation are often poorly understood. In Clostridioides d...

Natural genetic transformation is a conserved mechanism of bacterial horizontal gene transfer, which is directed entirely by the recipient cell and...

Abstract. Plasmids are important drivers of evolutionary transformations and ecological adaptation in prokaryotes. Plasmids supplying the host with benefic

Our understanding of chromosome organization and dynamics in spherical bacteria, such as Staphylococcus aureus, remains limited. Here, the authors show that chromosome replication and cell division cycles are not synchronized in S. aureus, with cells exhibiting two segregated origins of replication at the start of the cell cycle.

Wadjet is an SMC-based prokaryotic defense system that eliminates plasmid DNA. Roisné-Hamelin et al. present structures capturing key steps of its DNA-loading mechanism. This work reveals how Wadjet t...

Wadjet are SMC-based prokaryotic defense systems that cleave plasmid DNA. Roisné-Hamelin et al. reconstitute a type II Wadjet and demonstrate that it exhibits substrate selection and cleavage properti...

The first step of cell division is deforming the planar cell membrane inward towards the cytoplasm. As deforming membranes is energetically costly, biology has developed various protein systems to acc...

A DNA-binding protein, DnaA, regulates the initiation of chromosomal replication in bacteria. Here, Olivi et al. show that the bacterial chromosome sequesters DnaA in a growth rate-dependent manner, s...

Bacterial genomes often contain extrachromosomal replicons (ERs), ranging from small, mobile plasmids to large, stably inherited elements, such as meg…

Abstract. Ring-shaped sliding clamp proteins are essential components of the replication machinery across all domains of life. DNA polymerases bind the cla

Proteins SegA and SegB are important for chromosome segregation and organization in archaea of the order Sulfolobales, but mechanisms are unclear. Here, Kabli et al. uncover patterns and mechanisms th...

The pathogenic bacterium Vibrio cholerae typically has two circular chromosomes. Here, Cuénod et al. analyse 467 clinical isolates and identify several independent chromosome fusion events that are li...

YouTube video by Science Communication Lab

La résistance des bactéries aux antibiotiques est un phénomène qui s’accentue, créant un problème de santé publique majeur. Parmi les possibles alternatives aux antibiotiques, l’utilisation de virus i...

Integrons are genetic systems that drive bacterial adaptation by acquiring, expressing, and shuffling gene cassettes. While mobile integrons are well known for spreading antibiotic resistance genes, t...

Integrons are genetic systems that drive bacterial adaptation by acquiring, expressing, and shuffling gene cassettes. While mobile integrons are well known for spreading antibiotic resistance genes, t...

Plasmid conjugation is a contact-dependent horizontal gene transfer mechanism that significantly contributes to the dissemination of antibiotic res...

Bright and photostable monomeric fluorescent proteins enable long-term time-lapse imaging in E. coli.

Abstract. Nucleoid-associated proteins (NAPs) are crucial for maintaining chromosomal compaction and architecture, and are actively involved in DNA replica

While methylated cytosines are known to play important roles in eukaryotes, their significance in bacteria remains poorly understood especially when they are added on genomes by DNA methyltransferases...