ИСТИНА

Jumbo phages are a distinct type of bacteriophages characterized by their exceptionally large capsids, capable of packaging genomes exceeding 200 kbp—sizes approaching those of the smallest bacteria. This genome capacity enables them to employ versatile infection strategies, complex metabolic processes, and more effective evasion of bacterial antiviral defenses. Jumbo phages can encapsidate not only genomic DNA but also also a ready-to-use components of replication machinery such as the viral RNA polymerases. The large size of the virion particles, together with the complex protein composition, pose a significant challenge for determining the virion structure. Recent advances in cryoEM methods, however, have enabled the high-resolution reconstructions of bacteriophages. Although many phage structures have been solved in recent years, only two jumbo phage structures have been determined at high resolution [1,2]. This study focuses on resolving the structural composition of the novel Pseudomonas aeruginosa jumbo phage phiK601. The phage phiK601 was isolated from a water sample collected from Powai Lake in Mumbai, India, and purified extensively using CsCl gradient ultracentrifugation. We imaged the phage using cryo-electron microscopy and present a part-by-part single-particle reconstruction of the jumbo bacteriophage phiK601 virion.