Biology subjects

Molineux, I. J.

Publications and source records attributed to Molineux, I. J..

3 recordsLinked to original sources

bioRxiv2026

Sequential assembly in vivo of the bacteriophage P22 genome translocation channel

Bacteriophage P22 ejects four internal proteins into infected cells to assemble a channel for genome translocation across the cell envelope. However, how these proteins cooperate to build the trans-envelope channel remains enigmatic. Using in situ single-particle cryogenic electron microscopy, we determined near-atomic in vivo structures of P22 infection intermediates, revealing how the tail hub protein gp10 templates the sequential assembly of three internal proteins gp7*, gp20 and gp16 into a ~50-nm trans-envelope channel that extends from the virion into the host cytoplasm. Functional analyses explain why phage DNA can be detected in supernatant fluids during infection by channel-defective mutants. Our structures also provide a mechanistic basis for the long-standing observation that a P22 virion lacking gp16 can be complemented, extra-cytoplasmically, by a co-infecting virion lacking gp20, thereby allowing the genome in the gp16-deficient particle to enter the host cytoplasm.

microbiology↗

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↗

bioRxiv2019

Promises and pitfalls of in vivo evolution to improve phage therapy

(Background) Phage therapy is the use of bacterial viruses (phages) to treat bacterial infections. Phages lack the broad host ranges of antibiotics, so individual phages are often used with no prior history of use in treatment. Therapeutic phages are thus often chosen based on limited criteria, sometimes merely an ability to plate on the pathogenic bacterium. It is possible that better treatment outcomes might be obtained from an informed choice of phages. Here we consider whether phages used to treat the bacterial infection in a patient might specifically evolve to improve treatment. Phages recovered from the patient could then serve as a source of improved phages or cocktails for use on subsequent patients. (Methods) With the aid of mathematical and computational models, we explore this possibility for four phage properties expected to promote therapeutic success: in vivo growth, phage decay rate, overcoming resistant bacteria, and enzyme activity to degrade protective bacterial layers. (Results) Phage evolution only sometimes works in favor of treatment, and even in those cases, intrinsic phage dynamics in the patient are usually not ideal. An informed use of phages is invariably superior to reliance on within-host evolution and dynamics, although the extent of this benefit varies with the application.

microbiology↗