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).

The phage fought the cells, and the phage won: a satellite symposium at the ASV 2023 annual meeting.

This satellite symposium was focused on the molecular arms race between bacteria and their predators, the bacteriophages: who's the friend and who's the foe? This recounts highlights of the talks and presents food for thought and additional reflections on the current state of the field.

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.

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.

Phage defence by deaminase-mediated depletion of deoxynucleotides in bacteria.

Vibrio cholerae biotype El Tor is perpetuating the longest cholera pandemic in recorded history. The genomic islands VSP-1 and VSP-2 distinguish El Tor from previous pandemic V. cholerae strains.

Shigella viruses Sf22 and KRT47 require outer membrane protein C for infection.

Viruses rely on hosts for their replication: thus, a critical step in the infection process is identifying a suitable host cell. Bacterial viruses, known as bacteriophages or phages, often use receptor binding proteins to discriminate between susceptible and non-susceptible hosts. By being able to evade predation, bacteria with modified or deleted receptor-encoding genes often undergo positive selection during growth in the presence of phage.

Structure and physiology of giant DNA viruses.

Although giant viruses have existed for millennia and possibly exerted great evolutionary influence in their environment. Their presence has only been noticed by virologists recently with the discovery of Acanthamoeba polyphaga mimivirus in 2003. Its virion with a diameter of 500 nm and its genome larger than 1 Mpb shattered preconceived standards of what a virus is and triggered world-wide prospection studies.

Modeling the Effects of Calcium Overload on Mitochondrial Ultrastructural Remodeling.

Mitochondrial cristae are dynamic invaginations of the inner membrane and play a key role in its metabolic capacity to produce ATP. Structural alterations caused by either genetic abnormalities or detrimental environmental factors impede mitochondrial metabolic fluxes and lead to a decrease in their ability to meet metabolic energy requirements. While some of the key proteins associated with mitochondrial cristae are known, very little is known about how the inner membrane dynamics are involved in energy metabolism.

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.

The mitochondrial permeability transition phenomenon elucidated by cryo-EM reveals the genuine impact of calcium overload on mitochondrial structure and function.

Mitochondria have a remarkable ability to uptake and store massive amounts of calcium. However, the consequences of massive calcium accumulation remain enigmatic. In the present study, we analyzed a series of time-course experiments to identify the sequence of events that occur in a population of guinea pig cardiac mitochondria exposed to excessive calcium overload that cause mitochondrial permeability transition (MPT).

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.

Students' use of chemistry core ideas to explain the structure and stability of DNA.

Students tend to think of their science courses as isolated and unrelated to each other, making it difficult for them to see connections across disciplines. In addition, many existing science assessments target rote memorization and algorithmic problem-solving skills. Here, we describe the development, implementation, and evaluation of an activity aimed to help students integrate knowledge across introductory chemistry and biology courses.

Structural and Proteomic Characterization of the Initiation of Giant Virus Infection.

Since their discovery, giant viruses have expanded our understanding of the principles of virology. Due to their gargantuan size and complexity, little is known about the life cycles of these viruses. To answer outstanding questions regarding giant virus infection mechanisms, we set out to determine biomolecular conditions that promote giant virus genome release.

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.

A cornucopia of Shigella phages from the Cornhusker State.

Bacteriophages are abundant in the environment, yet the vast majority have not been discovered or described. Many characterized bacteriophages infect a small subset of Enterobacteriaceae hosts. Despite its similarity to Escherichia coli, the pathogenic Shigella flexneri has relatively few known phages, which exhibit significant differences from many E.

The phage L capsid decoration protein has a novel OB-fold and an unusual capsid binding strategy.

The major coat proteins of dsDNA tailed phages (order ) and herpesviruses form capsids by a mechanism that includes active packaging of the dsDNA genome into a precursor procapsid, followed by expansion and stabilization of the capsid. These viruses have evolved diverse strategies to fortify their capsids, such as non-covalent binding of auxiliary 'decoration' (Dec) proteins. The Dec protein from the P22-like phage L has a highly unusual binding strategy that distinguishes between nearly identical three-fold and quasi-three-fold sites of the icosahedral capsid.

Genes affecting progression of bacteriophage P22 infection in Salmonella identified by transposon and single gene deletion screens.

Bacteriophages rely on their hosts for replication, and many host genes critically determine either viral progeny production or host success via phage resistance. A random insertion transposon library of 240,000 mutants in Salmonella enterica serovar Typhimurium was used to monitor effects of individual bacterial gene disruptions on bacteriophage P22 lytic infection. These experiments revealed candidate host genes that alter the timing of phage P22 propagation.

Shigella Phages Isolated during a Dysentery Outbreak Reveal Uncommon Structures and Broad Species Diversity.

In 2016, Michigan experienced the largest outbreak of shigellosis, a type of bacillary dysentery caused by spp., since 1988. Following this outbreak, we isolated 16 novel -infecting bacteriophages (viruses that infect bacteria) from environmental water sources.

Breaking Symmetry in Viral Icosahedral Capsids as Seen through the Lenses of X-ray Crystallography and Cryo-Electron Microscopy.

The majority of viruses on Earth form capsids built by multiple copies of one or more types of a coat protein arranged with 532 symmetry, generating an icosahedral shell. This highly repetitive structure is ideal to closely pack identical protein subunits and to enclose the nucleic acid genomes. However, the icosahedral capsid is not merely a passive cage but undergoes dynamic events to promote packaging, maturation and the transfer of the viral genome into the host.

Microscopic Characterization of the Brazilian Giant Samba Virus.

Prior to the discovery of the mimivirus in 2003, viruses were thought to be physically small and genetically simple. Mimivirus, with its ~750-nm particle size and its ~1.2-Mbp genome, shattered these notions and changed what it meant to be a virus.