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J Gen Virol. 2010 Sep;91(Pt 9):2203-15. doi: 10.1099/vir.0.020958-0. Epub 2010 May 19.

Mutational analysis of the latency-associated nuclear antigen DNA-binding domain of Kaposi's sarcoma-associated herpesvirus reveals structural conservation among gammaherpesvirus origin-binding proteins.

Author information

1
Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL 32610-3633, USA.

Abstract

The latency-associated nuclear antigen (LANA) of Kaposi's sarcoma-associated herpesvirus functions as an origin-binding protein (OBP) and transcriptional regulator. LANA binds the terminal repeats via the C-terminal DNA-binding domain (DBD) to support latent DNA replication. To date, the structure of LANA has not been solved. Sequence alignments among OBPs of gammaherpesviruses have revealed that the C terminus of LANA is structurally related to EBNA1, the OBP of Epstein-Barr virus. Based on secondary structure predictions for LANA(DBD) and published structures of EBNA1(DBD), this study used bioinformatics tools to model a putative structure for LANA(DBD) bound to DNA. To validate the predicted model, 38 mutants targeting the most conserved motifs, namely three alpha-helices and a conserved proline loop, were constructed and functionally tested. In agreement with data for EBNA1, residues in helices 1 and 2 mainly contributed to sequence-specific DNA binding and replication activity, whilst mutations in helix 3 affected replication activity and multimer formation. Additionally, several mutants were isolated with discordant phenotypes, which may aid further studies into LANA function. In summary, these data suggest that the secondary and tertiary structures of LANA and EBNA1 DBDs are conserved and are critical for (i) sequence-specific DNA binding, (ii) multimer formation, (iii) LANA-dependent transcriptional repression, and (iv) DNA replication.

PMID:
20484563
PMCID:
PMC3066550
DOI:
10.1099/vir.0.020958-0
[Indexed for MEDLINE]
Free PMC Article

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