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| Open AccessThe virulence regulator VirB from Shigella flexneri uses a CTP-dependent switch mechanism to activate gene expression
Protein VirB regulates the expression of virulence genes in the pathogen Shigella flexneri by binding to DNA sequences far upstream of their promoters. Here, Jakob et al. show that VirB acts as a CTP-dependent molecular switch that uses a loading-and-sliding mechanism to control transcription of its target genes.
- Sara Jakob
- , Wieland Steinchen
- & Martin Thanbichler
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Article
| Open AccessA unique sigma/anti-sigma system in the actinomycete Actinoplanes missouriensis
Bacteria of the genus Actinoplanes form sporangia which, upon contact with water, release motile spores. Here, the authors study the mechanisms behind sporangium dehiscence and discover a sigma/anti-sigma system with unique features.
- Takeaki Tezuka
- , Kyota Mitsuyama
- & Yasuo Ohnishi
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| Open AccessDiversification of division mechanisms in endospore-forming bacteria revealed by analyses of peptidoglycan synthesis in Clostridioides difficile
The enzymes FtsW and FtsI are thought to be essential for the synthesis of septal peptidoglycan (PG) during bacterial cell division. Here, Shrestha et al. show that the pathogen Clostridioides difficile lacks a canonical FtsW/FtsI pair, with its homologs fulfilling sporulation-specific roles including the synthesis of septal PG during sporulation-specific cell division.
- Shailab Shrestha
- , Najwa Taib
- & Aimee Shen
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Article
| Open AccessDipM controls multiple autolysins and mediates a regulatory feedback loop promoting cell constriction in Caulobacter crescentus
Proteins with a catalytically inactive LytM-type endopeptidase domain regulate cell wall-degrading enzymes in bacteria. Here, Izquierdo-Martinez et al. show that one such protein, DipM, coordinates different peptidoglycan-remodeling pathways to ensure proper cell constriction and daughter cell separation in the model bacterium Caulobacter crescentus.
- Adrian Izquierdo-Martinez
- , Maria Billini
- & Martin Thanbichler
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Article
| Open AccessAllosteric activation of cell wall synthesis during bacterial growth
Coordination of cell wall assembly is critical for bacterial morphology and survival. Here, the authors show that activation of cell wall synthesis by the Rod complex is regulated by the structural dynamics of RodA-PBP2.
- Irina Shlosman
- , Elayne M. Fivenson
- & Joseph J. Loparo
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Article
| Open AccessA contractile injection system is required for developmentally regulated cell death in Streptomyces coelicolor
Bacteria can use extracellular contractile injection systems (eCISs) to inject toxic proteins into eukaryotic cells. Here, Vladimirov et al. provide evidence that the main role of eCISs in Streptomyces is not to attack other species, but to modulate the complex Streptomyces developmental process.
- Maria Vladimirov
- , Ruo Xi Zhang
- & Alan R. Davidson
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| Open AccessPhase separation modulates the assembly and dynamics of a polarity-related scaffold-signaling hub
The polarization of distinct scaffold-signaling hubs at opposite cell poles constitutes the basis of asymmetric cell division. Here, the authors show that phase separation serves as a general mechanism to regulate the assembly and dynamics of a new-pole scaffold-signaling hub.
- Wei Tan
- , Sihua Cheng
- & Wei Zhao
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| Open AccessAllosteric regulation of glycogen breakdown by the second messenger cyclic di-GMP
c-di-GMP has emerged as the signal controlling development in antibiotic producing Streptomyces. Here the authors describe another developmental role of c-di-GMP, in energy metabolism, by activating the glycogen-debranchingenzyme, GlgX. Structures revealing the activation mechanism are described.
- Maria A. Schumacher
- , Mirka E. Wörmann
- & Natalia Tschowri
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Article
| Open AccessLife at high temperature observed in vitro upon laser heating of gold nanoparticles
Studying microorganisms at high temperatures is challenging on conventional optical microscopes. Here, the authors introduce the concept of microscale laser heating over the full field of view by using gold nanoparticles as light absorbers, and study thermophile species up to 80 °C.
- Céline Molinaro
- , Maëlle Bénéfice
- & Guillaume Baffou
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| Open AccessThe obligate intracellular bacterium Orientia tsutsugamushi differentiates into a developmentally distinct extracellular state
Orientia tsutsugamushi (Ot) the causing agent of scrub typhus exits infected cells using a unique mechanism that involves budding off the surface of infected cells. Here, Atwal et al. report that Ots that have budded from their host cells are in a distinct developmental stage than intracellular bacteria and provide the first characterization of this extracellular stage. Both forms are infectious but differ in their physical properties, proteome, and entry mechanism into host cells.
- Sharanjeet Atwal
- , Jantana Wongsantichon
- & Jeanne Salje
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| Open AccessHyphal compartmentalization and sporulation in Streptomyces require the conserved cell division protein SepX
Streptomyces bacteria undergo two modes of cell division: formation of cross-walls in hyphae, leading to multicellular compartments, and septation for release of unicellular spores. Here, Bush et al. identify a protein that is important for both cell division modes in Streptomyces, likely by contributing to stabilization of the divisome.
- Matthew J. Bush
- , Kelley A. Gallagher
- & Susan Schlimpert
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Article
| Open AccessDormant spores sense amino acids through the B subunits of their germination receptors
Germination of Bacillus subtilis spores in response to L-alanine requires a putative membrane receptor consisting of three proteins. Here, Artzi et al. use evolutionary co-variation analysis and functional assays of mutants to provide evidence that one of the proteins, GerAB, likely acts as the L-alanine sensor.
- Lior Artzi
- , Assaf Alon
- & David Z. Rudner
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| Open AccessSpatial rearrangement of the Streptomyces venezuelae linear chromosome during sporogenic development
Streptomyces bacteria have a linear chromosome and a complex life cycle, including development of multi-genomic hyphae that differentiate into mono-genomic exospores. Here, Szafran et al. show that the chromosome of Streptomyces venezuelae undergoes substantial remodelling during sporulation, from an ‘open’ to a ‘closed’ conformation.
- Marcin J. Szafran
- , Tomasz Małecki
- & Dagmara Jakimowicz
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| Open AccessAn ambruticin-sensing complex modulates Myxococcus xanthus development and mediates myxobacterial interspecies communication
Starvation induces cell aggregation and formation of spore-containing fruiting bodies in the bacterium Myxococcus xanthus. Here, the authors show that a different myxobacterial species produces a compound that inhibits the development of fruiting bodies in M. xanthus, by affecting the function of histidine kinases and major regulators.
- Francisco Javier Marcos-Torres
- , Carsten Volz
- & Rolf Müller
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Article
| Open AccessDynamics of bacterial population growth in biofilms resemble spatial and structural aspects of urbanization
Bacterial biofilms develop from initial colonizers on surfaces that subsequently evolve into structured communities. Here, Paula et al. study this process in Streptococcus mutans and show growth dynamics that display spatial and structural patterns that are analogous to urbanization.
- Amauri J. Paula
- , Geelsu Hwang
- & Hyun Koo
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| Open AccessTwo-step chromosome segregation in the stalked budding bacterium Hyphomonas neptunium
In bacteria, DNA replication and segregation are commonly coupled. Here, by investigating the dynamics of these processes in the marine bacterium Hyphomonas neptunium, the authors unravel a two-step chromosomal segregation process reminiscent of eukaryotic mitosis, providing insights into the evolution of bacterial cell organization.
- Alexandra Jung
- , Anne Raßbach
- & Martin Thanbichler
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| Open AccessSingle-molecule imaging reveals modulation of cell wall synthesis dynamics in live bacterial cells
The bacterial cell wall is important for cell shape and stability, but how the activities of the biosynthetic machinery are coordinated are not clear. Here the authors use single-molecule imaging and chemical perturbations to determine factors that affect the localization dynamics of penicillin-binding proteins (PBP)1A and PBP1B.
- Timothy K. Lee
- , Kevin Meng
- & Kerwyn Casey Huang
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| Open AccessTopological control of the Caulobacter cell cycle circuitry by a polarized single-domain PAS protein
The bacterium Caulobacter crescentus is a model organism for research on the bacterial cell cycle and cell division processes. Here, Sanselicio et al. show that the MopJ protein contributes to the control of cell cycle and growth in C. crescentus.
- Stefano Sanselicio
- , Matthieu Bergé
- & Patrick H. Viollier