Publication Abstract from PubMed
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.
The cytomegalovirus DNA polymerase subunit UL44 forms a C clamp-shaped dimer.,Appleton BA, Loregian A, Filman DJ, Coen DM, Hogle JM Mol Cell. 2004 Jul 23;15(2):233-44. PMID:15260974[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
