Using cryogenic electron microscopy methods to gain insight into structure and initial host attachment of the flagellotropic bacteriophage 7-7-1

Noteborn, W. E. M.; Ouyang, R.; Hoeksma, T.; Sidi Mabrouk, A.; Esteves, N.; Pelt, D. M.; Scharf, B. E.; Briegel, A.

doi:10.1101/2025.01.29.635402

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bioRxiv · 10.1101/2025.01.29.635402

Using cryogenic electron microscopy methods to gain insight into structure and initial host attachment of the flagellotropic bacteriophage 7-7-1

Noteborn, W. E. M.·Ouyang, R.·Hoeksma, T.·Sidi Mabrouk, A.·Esteves, N.·Pelt, D. M.·Scharf, B. E.·Briegel, A.

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Abstract

Understanding the structural and functional mechanisms of bacteriophage 7-7-1, the flagellotropic phage infecting Agrobacterium sp. H13-3, offers promising insights into phage-host interactions. Using single particle analysis (SPA) cryo-electron microscopy (cryo-EM), we determined the capsid and tail structure, and built atomic models of capsid hexamers, pentamers and tail. Combined with cryo-electron tomography (cryo-ET) and machine learning methodologies, our findings indicate that phage 7-7-1 uses capsid fibers to establish initial contact with the host flagellum, followed by subsequent attachment to cell surface receptors. Proteinase K treatment confirmed the time-dependent degradation of capsid fibers. The study also demonstrated that capsid fibers are flexible and can interact with other phages and host flagella, suggesting a cooperative infection strategy. These results provide crucial structural insights and may open avenues for developing phage-based therapeutics against resistant bacterial pathogens.

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Noteborn, W. E. M., Ouyang, R., Hoeksma, T., Sidi Mabrouk, A., Esteves, N., Pelt, D. M., Scharf, B. E., Briegel, A.. 2025-01-29. Using cryogenic electron microscopy methods to gain insight into structure and initial host attachment of the flagellotropic bacteriophage 7-7-1. https://doi.org/10.1101/2025.01.29.635402

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