Cellular microbiology articles within Nature Communications

Here, Bhat et al. show that Influenza A virus mRNAs are exported from the nucleus via the nucleoporin Tpr and the mRNA export complex TREX-2. These mRNAs have low exon number, high mean exon length, and low GC content. A 45-nucleotide RNA signal can mediate export via TREX-2.

Dudek et al. describe rectangular bacterial structures in the mouths of dolphins. Using various genomic and microscopy techniques, they show that the structures consist of bacterial cells that appear to divide along the longitudinal axis and display other unusual features.

The pathogenic fungus Candida albicans can switch between a mating-competent form (“opaque” cells) and a form that is thought to be essentially sterile (“white” cells). Here, the authors show that glucose depletion, a common nutrient stress, enables C. albicans white cells to undergo efficient sexual mating.

Enteropathogenic bacteria use extracellular appendages, known as F-pili, to share plasmids carrying antibiotic resistance genes. Here, the authors show that F-pili are highly flexible but robust at the same time, and this is important for plasmid transfer and formation of biofilms that protect against the action of antibiotics.

Bacteria of the genus Streptomyces have complex life cycles involving cellular differentiation and multicellular structures that have never been observed in archaea. Here, the authors show that several halophilic archaea display a life cycle resembling that of Streptomyces bacteria, undergoing cellular differentiation into mycelia and spores.

Cable bacteria are centimeter-long filamentous microbes that conduct electrons via internal wires, thus coupling sulfide oxidation between sediment layers. Here, Bjerg et al. show that the anoxic part of oxygen-respiring cable bacteria attracts swarms of other bacteria, which appear to transfer electrons to cable bacteria via soluble metabolites.

IFT-A plays crucial roles in bidirectional ciliary transport, vital for cilia biogenesis and signaling. Here, Ma et al. report the IFT-A structure in two distinct states and unveil the assembly mechanism of IFT-A into the anterograde train.

Multicellular fungi have septal pores that allow cytoplasmic exchange between adjacent cells; cell wounding and other stress conditions induce septal pore closure. Here, Mamun et al. determine the subcellular localization of hundreds of uncharacterized proteins in a multicellular fungus, identifying 62 proteins associated with the septum. Of these, 23 proteins are involved in septal pore plugging upon hyphal wounding.

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.

Salmonella typhimurium translocates numerous effectors via its type III secretion system. Here, Göser et al. present a characterisation of selected proteins and their dynamic interaction with Salmonella-containing vacuoles and – induced filaments.

It has been proposed that bacterial membrane proteins may be produced via ‘transertion’, or concurrent transcription, translation and membrane insertion from membrane-associated genes. Here, Kaval et al. provide evidence supporting that Vibrio parahaemolyticus uses transertion to assemble a transmembrane complex (type III secretion system) used to inject virulence factors into host cells.

Temperature shapes the adaptation and composition of microbiomes, but whether their enzymes drive the thermal response remains unknown. Using an analysis of seven enzyme classes from worldwide marine microbiome data, this study shows that enzyme thermal properties explain microbial thermal plasticity and they are both finely tuned by the thermal variability of the environment.

Bacteria can affect cellular processes in other bacteria and in eukaryotic cells by injecting effectors using a type VI secretion system (T6SS). Here, Sá-Pessoa et al. describe how a T6SS effector from the bacterial pathogen Klebsiella pneumoniae triggers the fragmentation of the mitochondrial network in eukaryotic cells.

Exocytosis is a fundamental cellular process. Here, the authors report an unusual exocytosis mechanism in the silicified cell wall of diatoms, in which membrane patches are discarded.

Vimentin is an intermediate filament protein responsible for maintaining cell shape. Here, the authors characterise the role of the Salmonella effector SopB on the vimentin network and its contribution to infection.

Efficient metabolic regulation is key for parasite growth. Here, the authors report that Toxoplasma alters its AMPK phosphorylation during the lytic cycle, which reprograms parasite’s metabolism to ensure metabolic needs at different stages are met.

Conjugation is a contact-dependent mechanism for the transfer of plasmid DNA between bacterial cells. Here, Couturier et al. use live-cell microscopy to visualise the intracellular dynamics of conjugation in real time, revealing a molecular strategy that allows the sequential production of factors involved in establishing, maintaining and disseminating the plasmid.

The bacterium Brucella abortus is an intracellular pathogen that modulates autophagy in host cells. Here, the authors identify two B. abortus effectors that interact with host protease SENP3, thus promoting cytoplasmic accumulation of nucleolar proteins associated with ribosomal biogenesis and facilitating intracellular replication of the pathogen

Pathogenic fungi of the genus Cryptococcus can undergo bisexual and unisexual reproduction. Here, the authors construct a gene-deletion library for over 100 transcription factor genes in Cryptococcus deneoformans and provide insights into regulatory cascades that are specific for each reproductive mode.

The filamentous cyanobacterium Nostoc regulates communication between sister cells via a conformational change in septal junctions. Here, the authors identify and characterize protein SepN as a component of septal junctions, and highlight the importance of controlling molecular diffusion between cells to ensure the survival of a multicellular organism.

Pili are filamentous appendages on the surface of bacteria and archaea, and play roles in multiple processes such as adhesion, motility and horizontal gene transfer. Here, Gaines et al. describe the structure of a new type of pilus, termed ‘thread’, from the model archaeaon Sulfolobus acidocaldarius.

There is increasing evidence for metabolic processes mediating antimicrobial resistance. Here, the authors present a mechanism of sulfamethoxazole resistance in Group A Streptococcus that is dependent on acquiring end products of the host folate biosynthesis pathway.

Extensive lysosomal damage can result in cell death but how limited protease leakage affects cytoplasmic organelles in viable cells is not well understood. Here the authors show that limited lysosomal damage leads to changes in the mitochondrial proteome and the modulation of macrophage immunometabolism.

The bacterium Borrelia burgdorferi, which causes Lyme disease and is transmitted by ticks, has a linear chromosome and multiple plasmids. Here, Takacs et al. show that the pathogen is polyploid, the number of genome copies decreases during stationary phase, and chromosome copies are regularly spaced along the cell’s length.

Staphylococcus aureus is increasingly recognized as a facultative intracellular pathogen, but it is unclear whether the intracellular lifestyle is a general feature or is restricted to some isolates. Here, Rodrigues Lopes et al. profile the interaction of 191 clinical isolates with four host cell types over time, showing that almost all isolates are internalized and that a large fraction replicate and persist within host cells.

Fibres formed by protein TasA are important components of the extracellular matrix in biofilms developed by the bacterium Bacillus subtilis. Here, Böhning et al. use electron cryomicroscopy and other techniques to show how TasA globular monomers assemble through donor-strand exchange into β-sheet-rich fibres, which in turn assemble into bundles.

The cell wall and cytoplasmic MreB polymers are important for bacterial cell shape. However, Spiroplasma cells lack a cell wall and still display a helical shape and kink-based motility, which is thought to rely on five MreB isoforms and a fibril protein. Here, Lartigue et al. show that heterologous expression of a single Spiroplasma MreB isoform confers helical shape and kinking ability to Mycoplasma cells, which are naturally spherical and non-motile.

Bacterial symbionts, such as Wolbachia species, can manipulate the sexual development and reproduction of their insect hosts. Here, the authors identify a Wolbachia protein that interacts with a host masculinization factor and leads to male killing in lepidopteran insects.

Enterotoxigenic Escherichia coli infections have been linked to non-diarrheal sequelae however, the reasons for this are unclear. Here, the authors present an additional role of heat-labile toxin in disrupting the structure and function of intestinal epithelial cells.

Toxin B (TcdB) is a major exotoxin responsible for diseases associated with C. difficile infection. Here, Tian et al. show that several TcdB subtypes do not recognize the established FZD receptors, and identify a different host protein (TFPI) as a receptor for subtypes TcdB4 and TcdB10.

Bacteria can form organized multicellular communities through regulation of cell growth, motility, shape and differentiation. Here, Ellison et al. show that bacterial multicellular development can also be driven by specific patterns of localization of appendages known as type IV pili.

Uncultured bacteria of the genus Quinella are found in the rumen of ruminant animals, especially in sheep that emit low amounts of methane. Here, Kumar et al. reconstruct genomic sequences from Quinella cells to provide insights into their metabolic capabilities, including lactate and propionate formation as major fermentation pathways and an apparent lack of production of H₂, a major precursor of methane.

Uropathogenic strains of Escherichia coli (UPEC) are a leading cause of urinary tract infections (UTIs) and invasion involves Rho GTPase members, notably Rac1, to drive actin cytoskeleton rearrangement leading to engulfment. Here, Petracchini et al. provide evidence of an ECM stiffnessmodulated role of Optineurin (OPTN), which regulates HACE1-dependant Rac1 activity and thus controls integrinmediated mechanotransduction and bacterial invasion.

Bacterial cells at fluid interfaces can self-assemble into soft living materials, called pellicles. Here, Qin and Bassler use the bacterium Vibrio cholerae as a model system to identify regulatory and structural components that drive sequential mechanical instabilities underlying pellicle morphogenesis, culminating in fractal patterning.

The carcinogenic bacterium Helicobacter pylori infects gastric cells. Here, the authors show that H. pylori preferentially infects differentiated cells in the pit region of gastric units, and this relies on bacterial chemotaxis towards host cell-released urea, which scales with host cell size.

Transitioning from spores to hyphae is crucial for host invasion by the plant pathogenic fungus Zymoseptoria tritici. Here, the authors show that the spore-to-hypha transition is enhanced by wheat leaf surface compounds and is regulated by the white-collar complex, which integrates light with biotic and abiotic cues to allow host invasion through open stomata.

Magnetotactic bacteria use intracellular chains of ferrimagnetic nanocrystals, produced within magnetosome organelles, to align and navigate along the geomagnetic field. Here, Wan et al. identify two proteins involved in magnetosome positioning in Magnetospirillum magneticum, homologs of which are widespread among magnetotactic bacteria.

“Intracellular phase separation is emerging as a universal principle for organizing biochemical reactions in time and space. Here the authors show that PopZ condensate dynamics support cell division and using PopZ modular architecture, the tunable PopTag platform was developed to enable designer condensates.”

Horizontal gene transfer in bacteria can occur through mechanisms such as conjugation, transduction and transformation, which facilitate the passage of DNA across the cell wall. Here, Kapteijn et al. show that cell wall-deficient bacteria can take up DNA and other extracellular materials via an endocytosis-like process.

Perinatal infection with Group B Streptococcus (GBS) is associated with preterm birth, neonatal sepsis, and stillbirth. Here, Korir et al. show that gene cadD, encoding a putative metal efflux transporter, is important for metal detoxification, immune evasion and bacterial proliferation in the pregnant host.

Lipids shed by pathogenic mycobacteria have been shown to inhibit NPC1, a lysosomal membrane protein deficient in most cases of a rate inherited lysosomal storage disorder Niemann-Pick disease type C (NPC). Here, authors utilise lipid extracts from clinical Mycobacterium tuberculosis strains, and non-tubercular mycobacteria to investigate their ability to inhibit the NPC pathway.

Rod-shaped bacteria typically elongate and divide by transverse fission, but a few species are known to divide longitudinally. Here, the authors use genomic, phylogenetic and microscopy techniques to shed light on the evolution of cell shape, multicellularity and division mode within the family Neisseriaceae.

Some bacteria act as pathogens or predators of other bacteria, but their impact in natural settings is often unclear. Here, Bethany et al. describe a new type of obligate, intracellular predatory bacterium of widespread distribution that preys on soil cyanobacteria in biocrusts and thus severely impacts biocrust productivity.

In E. coli, disruption of TopoI and RNAP interaction decreases cells viability and leads to hypernegative DNA supercoiling and R loops accumulation. TopoI and DNA gyrase bind around transcription units and TopoI recognizes cleavage sites by a specific motif and negative supercoiling.

Chromosomal instability caused by cell division errors is associated with antifungal drug resistance in fungal pathogens. Here, Jaitly et al. identify several genes involved in chromosomal stability in Candida albicans, including a phylogenetically restricted gene encoding an essential cell-cycle progression factor.

Encystment is a process that allows free-living and parasitic amoebae to survive in unfavorable environments. Here, Bernard et al. provide detailed insights into the early stages of encystment of Acanthamoeba castellanii by integrating RNA-Seq, proteomics and phosphoproteomics data sets.

The fungal pathogen Candida albicans forms filamentous hyphae that can invade the epithelium. Here, Lachat et al. show that C. albicans early invasion of epithelial tissues can lead to either host membrane breaching and host cell death, or trans-cellular tunnelling through host cells without membrane breaching.

Pathogenic Rickettsia species are arthropod-borne, obligate intracellular bacteria that invade host cells, replicate in the cell cytosol, and spread from cell to cell. Here, Borgo et al. identify a Rickettsia phospholipase enzyme that is important for infection by helping the bacteria escape from host cell vacuoles into the host cytosol, preventing targeting by autophagy, and promoting bacterial motility and spread to other cells.

Mycobacterium marinum, a close relative of Mycobacterium tuberculosis, polymerizes host actin at the bacterial surface to drive intracellular movement and cell-to-cell spread during infection. Here, Hill & Welch identify an M. marinum surface protein that binds to and activates the host protein NWASP to stimulate actin polymerization and drive bacterial actin-based motility.