Biology subjects

Robins, W. P. P.

Publications and source records attributed to Robins, W. P. P..

3 recordsLinked to original sources

bioRxiv2026

Structural basis of multimodal adsorption and infection initiation by Vibrio phage Peru-2

Phage Peru-2, isolated during the 1993 cholera outbreaks in Peru, is distinct from the three ICP phage lineages typically associated with epidemic Vibrio cholerae. The molecular basis of Peru-2 adsorption and infection initiation has remained unknown. Here, we combine single-particle cryo-electron microscopy (cryo-EM) and cryo-electron tomography (cryo-ET) to define the architecture and infection mechanisms of Peru-2 at high resolution. The mature virion comprises an icosahedral capsid decorated with minor capsid proteins and a short tail apparatus surrounded by six structurally flexible tailspikes. These tailspikes are enzymatically active in mediating phage attachment to the Vibrio polysaccharide (VPS), a key component of biofilms. Three internal core proteins form a disordered core adjacent to the portal, positioning them for release before genome ejection during infection initiation. Structural analyses further resolve pre-ejection, genome-ejection, and post-ejection intermediates of the tail apparatus, while cryo-ET imaging of infected cells reveals a multimodal adsorption strategy during infection initiation. SignificanceVibrio phages play important ecological and evolutionary roles, yet the structural basis underlying their host recognition and adsorption strategies has remained poorly understood. Here, we determine the overall architecture of Vibrio phage Peru-2 at near-atomic resolution, showing that it shares a conserved molecular organization with T7-like podophages but possesses additional minor capsid proteins and a distinct tailspike. In addition, Peru-2 interacts extensively with both the bacterial cell surface and sheathed flagella, revealing multiple modes of adsorption strategy distinct from those of classic T7 infection. Our structural analyses and functional evidence that Vibrio polysaccharide is required for Peru-2 adsorption and infection provide a mechanistic framework for understanding host recognition and infection strategies among Vibrio phages.

microbiology↗

bioRxiv2026

An Aeromonad selectively removes a class of pathogens from shrimp, prevents disease and preserves a healthy commensal microbiome

On their own, probiotics do not entirely eliminate pathogens during infection and disease. Instead, they often serve as adjuncts that rely on distinct mechanisms to reduce the presence of harmful bacteria. Our prior research indicates that an isolated Aeromonas dhakensis strain A603 kills pathogenic Vibrio strains through two antibacterial mechanisms: the type VI secretion system (T6SS) and phenazine (AdPhen). Here, we investigate A603 as a standalone probiotic for a shrimp disease model. This study shows that A603 prevents mortality from acute hepatopancreatic necrosis disease (AHPND) in shrimp caused by pathogenic Vibrio spp. that produce the PirAB toxin. AHPND infection alters the shrimp microbiota by increasing pathogen abundance and decreasing beneficial bacterial abundance prior to death. As both a prophylactic and treatment, A603 removes pathogenic Vibrio from shrimp and reverses such alterations in the microbiota using both T6SS and AdPhen. Collectively, our findings show that A603 antibacterial mechanisms prevent AHPND.

microbiology↗

bioRxiv2025

The spike tip protein of bacteriophage T4

Contractile injection systems (CISs) - bacteriophage tails, tailocins, and bacterial type VI secretion systems - penetrate the envelope of the target cell by employing a contractile sheath-rigid tube mechanism. The membrane-attacking end of the tube carries a spike-shaped complex that ends with a spike tip. In bacteriophage P2, the spike and spike tip proteins are fused, and we used this phage to show that sheath contraction results in the translocation of the spike into the periplasm of the host cell. In bacteriophage T4, the spike and spike tip proteins are encoded by different genes. We show that the ORFan gene 5.4 codes for the spike tip protein of bacteriophage T4. Using an amber nonsense mutation, we show that the gp5.4 protein is dispensable for bacteriophage T4 particle assembly but essential for bacteriophage fitness and infection of bacteria with truncated lipopolysaccharides.

molecular biology↗