Download MendeleyThe Cytomegalovirus DNA Polymerase Subunit UL44 Forms a C Clamp-Shaped Dimer.
Appleton, B.A., Loregian, A., Filman, D.J., Coen, D.M., Hogle, J.M.(2004) Mol Cell 15: 233-244
- PubMed: 15260974
- DOI: https://doi.org/10.1016/j.molcel.2004.06.018
- Primary Citation of Related Structures:
1T6L - PubMed Abstract:
The human cytomegalovirus DNA polymerase consists of a catalytic subunit, UL54, and a presumed processivity factor, UL44. We have solved the crystal structure of residues 1-290 of UL44 to 1.85 A resolution by multiwavelength anomalous dispersion. The structure reveals a dimer of UL44 in the shape of a C clamp. Each monomer of UL44 shares its overall fold with other processivity factors, including herpes simplex virus UL42, which is a monomer that binds DNA directly, and the sliding clamp, PCNA, which is a trimer that surrounds DNA, although these proteins share no obvious sequence homology. Analytical ultracentrifugation and gel filtration measurements demonstrated that UL44 also forms a dimer in solution, and substitution of large hydrophobic residues along the homodimer interface with alanine disrupted dimerization and decreased DNA binding. UL44 represents a hybrid processivity factor as it binds DNA directly like UL42, but forms a C clamp that may surround DNA like PCNA.
Organizational Affiliation:
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
