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Researchers used cryo-electron microscopy to determine the high-resolution structures of AbP20, a podovirus that infects the multidrug-resistant bacterium Acinetobacter baumannii, including both its mature form and its procapsid precursor. The study revealed AbP20 consists of five distinct structural components and identified the molecular mechanisms of capsid assembly and maturation, showing a canonical conformational switch from procapsid to mature capsid. This represents the first complete atomic-level structure of a podovirus targeting A. baumannii.
Why it matters
This structural information provides a foundation for engineering and modifying phages to combat multidrug-resistant A. baumannii infections, which is increasingly important as antibiotic resistance rises. The detailed molecular blueprint could enable rational design of more effective therapeutic phages for precision medicine applications.
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⚠️ Preprint – Noch nicht peer-reviewed
Dieser Artikel wurde noch nicht von unabhängigen Experten begutachtet. Die Ergebnisse sind vorläufig und sollten mit Vorsicht interpretiert werden.
Phages that hunting multidrug resistant bacteria represent a promising approach in precision medicine nowadays, including these infecting Acinetobacter baumannii. To data, a large number of A. baumannii phages has been isolated, however, complete structural information remains not adequately released. Previously, we reported a podovirus, AbP20, that infects A. baumannii with potent efficacy in mouse model. In the present work, we further report the high-resolution cryo-electron microscopy (cryo-EM) structures of AbP20 and its procapsid. The near-atomic resolution reveals that AbP20 is composed of five distinct structural subunits, i.e., capsid, portal, nozzle, fiber, and adaptor. We then characterized the assembly mechanisms of molecular interactions within capsid and portal-tail complex. By co-expressing the scaffold protein and the capsid protein of AbP20, we constructed the self-assembled DNA-free procapsid of AbP20. A near-atomic resolution reconstruction reveals it a double-layered concentric spherical architecture with a nearly 1:1 ratio of these two proteins. Comparison between the mature and apo-form of the capsid of AbP20 uncovers a canonical model of conformational switch from procapsid to capsid. Altogether, the present work reports the first whole atom structure of a podovirus infecting A. baumannii, providing a reference for structure-based phage engineering and editing.
Source: Cryo-EM structures of an Acinetobacter baumannii podovirus reveal a canonical capsid maturation