A split nozzle and two-protein chain-like fibers define the tail architecture of Pseudomonas aeruginosa podophage A1002

Phage therapy offers unique advantages against antibiotic-resistant bacteria. However, high-resolution structural studies of phages targeting Pseudomonas aeruginosa —a top-seven global pathogen—particularly podophages, remain severely limited, directly impeding structure-based development of novel antimicrobials. In this study, we utilize cryo-EM to resolve the high-resolution intact structure of mature phage A1002, a podophage infecting carbapenem-resistant P. aeruginosa . Based on density maps combined with AlphaFold3 predictions, we identified 11 structural protein components from the head to the tail. Phage A1002 exhibits a distinctly elongated tail morphology distinct from other reported podophages. Notably, the A1002 nozzle employs a distinct assembly strategy, featuring the unique nozzle-rope protein and nozzle-base protein, which may have evolved through modular evolution and horizontal gene transfer. Furthermore, the nozzle-rope protein provides 11 adsorption sites for fiber dimers, and these dimers are assembled from two proteins, giving rise to two types of dimers: dimers 1–7 correspond to fiber I (gp40), and dimers 8–11 correspond to fiber II (gp41). The nozzle-rope protein and these dimers combine to form a chain-like fiber. The tail tube comprises a double-layered, elongated tube structure that functions to simultaneously increase tail length and provide docking sites for six chain-like fibers. These distinctive structural features provide the molecular basis for A1002’s broad-spectrum infection of drug-resistant P. aeruginosa and offer a novel molecular blueprint for rational design of structure-guided phage therapeutics.