Moo19 and B2: Structures of podophages with = 9 geometry and tailspikes with esterase activity.

Podophages are, by far, the least well studied of all the bacteriophages. Despite being classified together due to their short, noncontractile tails, there is a huge amount of diversity among members of this group. Of the podophages, the N4-like family is the least well studied structurally and is quite divergent from well-characterized podophages such as T7 and P22.

Phage Hunting in the High School Classroom: Phage Isolation and Characterization.

National science, technology, engineering, and mathematics education emphasizes science practices, such as hands-on learning. We describe a week-long activity where students participate in real-world scientific discovery, including "hunting" for bacteriophage in a variety of environmental samples. First, the students collect samples, then look for evidence of phage on "bait" bacteria, and finally amplify/purify the phages for further study.

A viral satellite maximizes its spread and inhibits phage by remodeling hijacked phage coat proteins into small capsids.

Phage satellites commonly remodel capsids they hijack from the phages they parasitize, but only a few mechanisms regulating the change in capsid size have been reported. Here, we investigated how a satellite from , phage-inducible chromosomal island-like element (PLE), remodels the capsid it has been predicted to steal from the phage ICP1 (Netter et al., 2021).

Cryo-EM structure of a Shigella podophage reveals a hybrid tail and novel decoration proteins.

There is a paucity of high-resolution structures of phages infecting Shigella, a human pathogen and a serious threat to global health. HRP29 is a Shigella podophage belonging to the Autographivirinae family, and has very low sequence identity to other known phages. Here, we resolved the structure of the entire HRP29 virion by cryo-EM.

PlzD modifies foraging behavior and virulence in response to elevated c-di-GMP.

Many free-swimming bacteria propel themselves through liquid using rotary flagella, and mounting evidence suggests that the inhibition of flagellar rotation initiates biofilm formation, a sessile lifestyle that is a nearly universal surface colonization paradigm in bacteria. In general, motility and biofilm formation are inversely regulated by the intracellular second messenger bis-(3´-5´)-cyclic dimeric guanosine monophosphate (c-di-GMP). Here, we identify a protein, PlzD, bearing a conserved c-di-GMP binding PilZ domain that localizes to the flagellar pole in a c-di-GMP-dependent manner and alters the foraging behavior, biofilm, and virulence characteristics of the opportunistic human pathogen, .

A viral satellite maximizes its spread and inhibits phage by remodeling hijacked phage coat proteins into small capsids.

Phage satellites commonly remodel capsids they hijack from the phages they parasitize, but only a few mechanisms regulating the change in capsid size have been reported. Here, we investigated how a satellite from , PLE, remodels the capsid it has been predicted to steal from the phage ICP1 (1). We identified that a PLE-encoded protein, TcaP, is both necessary and sufficient to form small capsids during ICP1 infection.

Complete Genome Sequences of Genamy16 and NovaSharks, Two Gordonia rubripertincta Bacteriophages Isolated from Soil in Southeastern Florida.

We report on two actinobacteriophages, Genamy16 and NovaSharks, that were isolated from soil in Florida using Gordonia rubripertincta NRRL B-16540. The genomes of both phages are ~65,000 bp, with similar GC contents, and, based on gene content similarity to phages in the Actinobacteriophage Database, were assigned to phage cluster DV.

Host Range Expansion of Phage Sf6 Evolves through Point Mutations in the Tailspike.

The first critical step in a virus's infection cycle is attachment to its host. This interaction is precise enough to ensure the virus will be able to productively infect the cell, but some flexibility can be beneficial to enable coevolution and host range switching or expansion. Bacteriophage Sf6 utilizes a two-step process to recognize and attach to its host Shigella flexneri.

Spore-Associated Proteins Involved in c-di-GMP Synthesis and Degradation of Bacillus anthracis.

Bis-(3'-5')-cyclic-dimeric GMP (c-di-GMP) is an important bacterial regulatory signaling molecule affecting biofilm formation, toxin production, motility, and virulence. The genome of Bacillus anthracis, the causative agent of anthrax, is predicted to encode ten putative GGDEF/EAL/HD-GYP-domain containing proteins. Heterologous expression in Bacillus subtilis hosts indicated that there are five active GGDEF domain-containing proteins and four active EAL or HD-GYP domain-containing proteins.

Large metabolic rewiring from small genomic changes between strains of .

The instability of genomes has been described, but how this instability causes phenotypic differences within the species is largely unknown and likely variable. We describe herein the genome of strain PE577, originally a clinical isolate, which exhibits several phenotypic differences compared to the model strain 2457T. Like many previously described strains of , PE577 lacks discernible, functional CRISPR and restriction-modification systems.

Promotion of CTL epitope presentation by a nanoparticle with environment-responsive stability and phagolysosomal escape capacity.

Vaccines that induce cytotoxic T lymphocyte (CTL)-mediated immune responses constitute an important class of medical tools to fend off diseases like infections and malignancy. Epitope peptides, as a format of CTL vaccines, are being tested preclinically and clinically. To elicit CTL responses, epitope vaccines go through an epitope presentation pathway in dendritic cells (DCs) that has multiple bottleneck steps and hence is inefficient.

Ecology, Structure, and Evolution of Phages.

Numerous bacteriophages-viruses of bacteria, also known as phages-have been described for hundreds of bacterial species. The Gram-negative species are close relatives of , yet relatively few previously described phages appear to exclusively infect this genus. Recent efforts to isolate phages have indicated these viruses are surprisingly abundant in the environment and have distinct genomic and structural properties.

Functional Regulators of Bacterial Flagella.

Bacteria move by a variety of mechanisms, but the best understood types of motility are powered by flagella (72). Flagella are complex machines embedded in the cell envelope that rotate a long extracellular helical filament like a propeller to push cells through the environment. The flagellum is one of relatively few biological machines that experience continuous 360° rotation, and it is driven by one of the most powerful motors, relative to its size, on earth.

The C-Terminal Region of Bacillus subtilis SwrA Is Required for Activity and Adaptor-Dependent LonA Proteolysis.

SwrA is the master activator of flagellar biosynthesis in , and SwrA activity is restricted by regulatory proteolysis in liquid environments. SwrA is proteolyzed by the LonA protease but requires a proteolytic adaptor protein, SmiA. Here, we show that SwrA and SmiA interact directly.

MotI (DgrA) acts as a molecular clutch on the flagellar stator protein MotA in .

Stator elements consisting of MotAMotB complexes are anchored to the cell wall, extend through the cell membrane, and interact with FliG in the cytoplasmic C ring rotor of the flagellum. The cytoplasmic loop of MotA undergoes proton-driven conformational changes that drive flagellar rotation. Functional regulators inhibit motility by either disengaging or jamming the stator-rotor interaction.

SwrD (YlzI) Promotes Swarming in Bacillus subtilis by Increasing Power to Flagellar Motors.

The bacterium is capable of two kinds of flagellum-mediated motility: swimming, which occurs in liquid, and swarming, which occurs on a surface. Swarming is distinct from swimming in that it requires secretion of a surfactant, an increase in flagellar density, and perhaps additional factors. Here we report a new gene, , located within the 32 gene operon dedicated to flagellar biosynthesis and chemotaxis, which when mutated abolished swarming motility.

Engineering of Bacillus subtilis strains to allow rapid characterization of heterologous diguanylate cyclases and phosphodiesterases.

Microbial processes, including biofilm formation, motility, and virulence, are often regulated by changes in the available concentration of cyclic dimeric guanosine monophosphate (c-di-GMP). Generally, high c-di-GMP concentrations are correlated with decreased motility and increased biofilm formation and low c-di-GMP concentrations are correlated with an increase in motility and activation of virulence pathways. The study of c-di-GMP is complicated, however, by the fact that organisms often encode dozens of redundant enzymes that synthesize and hydrolyze c-di-GMP, diguanylate cyclases (DGCs), and c-di-GMP phosphodiesterases (PDEs); thus, determining the contribution of any one particular enzyme is challenging.