The clamp-loading complex for processive DNA replication.
DNA polymerase requires two processing factors, sliding clamps and clamp loaders, to direct rapid and accurate duplication of genomic DNA. In eukaryotes, proliferating cell nuclear antigen (PCNA), the ring-shaped sliding clamp, encircles double-stranded DNA within its central hole and tethers the DNA polymerases onto DNA. Replication factor C (RFC) acts as the clamp loader, which correctly installs the sliding clamp onto DNA strands in an ATP-dependent manner. Here we report the three-dimensional structure of an archaeal clamp-loading complex (RFC-PCNA-DNA) determined by single-particle EM. The three-dimensional structure of the complex, reconstituted in vitro using a nonhydrolyzable ATP analog, reveals two components, a closed ring and a horseshoe-shaped element, which correspond to PCNA and RFC, respectively. The atomic structure of PCNA fits well into the closed ring, suggesting that this ternary complex represents a state just after the PCNA ring has closed to encircle the DNA duplex.
Miyata
Tomoko
T
Department of Structural Biology, Biomolecular Engineering Research Institute, Suita, Osaka 565-0874, Japan.
Oyama
Takuji
T
Mayanagi
Kouta
K
Ishino
Sonoko
S
Ishino
Yoshizumi
Y
Morikawa
Kosuke
K
D000255:Adenosine Triphosphate / Q000378:metabolism; D001483:Base Sequence; D004247:DNA / Q000378:metabolism*; D017931:DNA Primers; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D006868:Hydrolysis; D008854:Microscopy, Electron
D017931:DNA Primers; D004268:DNA-Binding Proteins; D000255:Adenosine Triphosphate; D004247:DNA