The Crystal Structure of the Herpes Simplex Virus 1 ssDNA-binding Protein Suggests the Structural Basis for Flexible, Cooperative Single-stranded DNA Binding.

All organisms including animal viruses use specific proteins to bind single-stranded DNA rapidly in a nonsequence-specific, flexible, and cooperative manner during the DNA replication process. The crystal structure of a 60-residue C-terminal deletion construct of ICP8, the major single-stranded DNA-binding protein from herpes simplex virus-1, was determined at 3.0 Å resolution. The structure reveals a novel fold, consisting of a large N-terminal domain (residues 9-1038) and a small C-terminal domain (residues 1049-1129). On the basis of the structure and the nearest neighbor interactions in the crystal, we have presented a model describing the site of single-stranded DNA binding and explaining the basis for cooperative binding. This model agrees with the beaded morphology observed in electron micrographs. [ABSTRACT FROM AUTHOR]