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In situ Subcellular Fractionation of Adherent and Non-adherent Mammalian Cells
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Interaction with TopBP1 Is Required for Human Papillomavirus 16 E2 Plasmid Segregation/Retention Function during
Apurva T Prabhakar1, Claire D James1, Dipon Das1
1Virginia Commonwealth Universitygrid.224260.0 (VCU), Philips Institute for Oral Health Research, School of Dentistry, Richmond, Virginia, USA.
Journal of Virology
|July 26, 2022
Summary
Human papillomavirus 16 E2 protein ensures viral genome segregation by interacting with host protein TopBP1. This interaction is crucial for E2
Area of Science:
- Virology
- Molecular Biology
- Cell Biology
Background:
- Human papillomavirus 16 (HPV16) E2 protein regulates viral genome functions, including potential segregation during cell division.
- The host cell factor mediating E2's segregation function has remained unidentified.
- Previous work showed CK2 phosphorylation of E2 at S23 is necessary for TopBP1 interaction and recruitment to mitotic chromatin.
Purpose of the Study:
- To investigate the role of the E2-TopBP1 interaction in HPV16 genome segregation.
- To determine if TopBP1 is the host chromatin receptor for E2's segregation function.
- To elucidate the mechanism by which E2 achieves plasmid segregation during mitosis.
Main Methods:
- Utilizing U2OS cells expressing wild-type E2 and a non-binding mutant (S23A).
- Employing quantitative segregation assays in U2OS and N/Tert-1 cells.
- Performing siRNA knockdown of TopBP1 and CK2 components.
Main Results:
- E2-TopBP1 interaction is essential for recruiting HPV16 plasmids to mitotic chromatin.
- TopBP1 interaction is required for E2's plasmid segregation function in multiple cell types.
- Disruption of TopBP1 or CK2 function impairs E2 segregation.
- E2-TopBP1 interaction increases E2 protein levels during mitosis.
Conclusions:
- HPV16 E2 protein possesses plasmid segregation activity.
- The E2-TopBP1 interaction is critical for mediating HPV16 genome segregation.
- This interaction enhances E2 protein stability during mitosis, supporting its segregation function.
- The findings reveal a mechanism for HPV16 genome maintenance during infection.
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