DNA mapping in the capsid of giant bacteriophage phiEL (Caudovirales: Myoviridae: Elvirus) by analytical electron microscopy

Autor: T. S. Trifonova, A. V. Moiseenko, M. V. Bourkaltseva, O. V. Shaburova, A. K. Shaytan, V. N. Krylov, O. S. Sokolova
Jazyk: English<br />Russian
Rok vydání: 2022
Předmět:
Zdroj: Вопросы вирусологии, Vol 66, Iss 6, Pp 434-441 (2022)
Druh dokumentu: article
ISSN: 0507-4088
2411-2097
DOI: 10.36233/0507-4088-80
Popis: Introduction. Giant phiKZ-like bacteriophages have a unique protein formation inside the capsid, an inner body (IB) with supercoiled DNA molecule wrapped around it. Standard cryo-electron microscopy (cryo-EM) approaches do not allow to distinguish this structure from the surrounding nucleic acid of the phage. We previously developed an analytical approach to visualize protein-DNA complexes on Escherichia coli bacterial cell slices using the chemical element phosphorus as a marker. In the study presented, we adapted this technique for much smaller objects, namely the capsids of phiKZ-like bacteriophages. Material and methods. Following electron microscopy techniques were used in the study: analytical (AEM) (electron energy loss spectroscopy, EELS), and cryo-EM (images of samples subjected to low and high dose of electron irradiation were compared). Results. We studied DNA packaging inside the capsids of giant bacteriophages phiEL from the Myoviridae family that infect Pseudomonas aeruginosa. Phosphorus distribution maps were obtained, showing an asymmetrical arrangement of DNA inside the capsid. Discussion. We developed and applied an IB imaging technique using a high angle dark-field detector (HAADF) and the STEM-EELS analytical approach. Phosphorus mapping by EELS and cryo-electron microscopy revealed a protein formation as IB within the phage phiEL capsid. The size of IB was estimated using theoretical calculations. Conclusion. The developed technique can be applied to study the distribution of phosphorus in other DNA- or RNA-containing viruses at relatively low concentrations of the element sought.
Databáze: Directory of Open Access Journals
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