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Interaction of human papillomavirus (HPV) type 16 capsid proteins with HPV DNA requires an intact L2 N-terminal
1Papillomavirus Research Unit, University of Queensland, Princess Alexandra Hospital, Woolloongabba, Australia.
Abstract:
Encapsidation of papillomavirus DNA involves DNA-protein and protein-protein interactions. We sought to define the role of each human papillomavirus (HPV) capsid protein in HPV DNA encapsidation. HPV16 major (L1) and minor (L2) capsid proteins purified from recombinant vaccinia virus-infected cells were compared for their ability to bind nucleic acids. L2 protein, but not L1 protein, could bind HPV DNA. To map the DNA-binding region of L2, a series of truncated or point-mutated L2 protein open reading frames were used to show that only the N terminal of L2 was required for L2-DNA binding. This interaction depends critically on charged amino acids (Lys or Arg) in the first 12 amino acids of the N terminal of the protein. Several techniques were used to show that L2 interaction with DNA did not require specific DNA sequences. We propose that HPV L2 protein may play a major role in papillomavirus capsid assembly by introducing HPV DNA to the virus particles formed by the self assembly of the L1 major structural protein.
Insights
Human papillomavirus (HPV) minor capsid protein L2, not L1, binds HPV DNA. The N-terminal region of L2, rich in charged amino acids, is crucial for this DNA interaction during viral assembly.
Area of Science:
- Virology
- Molecular Biology
- Structural Biology
Background:
- Papillomavirus DNA encapsidation relies on complex DNA-protein and protein-protein interactions.
- Understanding the specific roles of viral capsid proteins is essential for deciphering viral assembly mechanisms.
Purpose of the Study:
- To determine the individual roles of human papillomavirus (HPV) major (L1) and minor (L2) capsid proteins in HPV DNA encapsidation.
- To identify the specific regions and characteristics of L2 protein responsible for DNA binding.
Main Methods:
- Purification of HPV16 L1 and L2 capsid proteins from recombinant vaccinia virus-infected cells.
- Assessment of nucleic acid binding capabilities of purified L1 and L2 proteins.
- Analysis of truncated and point-mutated L2 protein variants to map DNA-binding domains.
- Utilizing multiple techniques to confirm L2-DNA interaction and sequence independence.
Main Results:
- HPV L2 protein demonstrated significant binding to HPV DNA, while L1 protein did not.
- The N-terminal region of the L2 protein was identified as the critical domain for DNA binding.
- Specific charged amino acids (Lysine or Arginine) within the first 12 amino acids of L2 are essential for DNA interaction.
- L2-DNA binding was found to be independent of specific DNA sequences.
Conclusions:
- The HPV L2 protein plays a pivotal role in initiating papillomavirus capsid assembly by binding viral DNA.
- L2 likely facilitates the introduction of HPV DNA into viral particles, which are primarily formed by the self-assembly of the L1 major structural protein.
- These findings elucidate a key mechanism in papillomavirus replication and assembly.