期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 106, 期 49, 页码 20693-20698出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.0907780106
关键词
DNA clamp; DNA replication; electron microscopy; fidelity control; protein crystallography
资金
- Ministry of Education, Culture, Sports, Science, and Technology of Japan
- Institute for Bioinformatics Research and Development, Japan Science and Technology Agency
- Core Research for Evolutional Science and Technology, Japan Science and Technology Agency
Proliferating cell nuclear antigen (PCNA) is responsible for the processivity of DNA polymerase. We determined the crystal structure of Pyrococcus furiosus DNA polymerase (PfuPol) complexed with the cognate monomeric PCNA, which allowed us to construct a convincing model of the polymerase-PCNA ring interaction, with unprecedented configurations of the two molecules. Electron microscopic analyses indicated that this complex structure exists in solution. Our structural study revealed that an interaction occurs between a stretched loop of PCNA and the PfuPol Thumb domain, in addition to the authentic PCNA-polymerase recognition site (PIP box). Comparisons of the present structure with the previously reported structures of polymerases complexed with DNA, suggested that the second interaction plays a crucial role in switching between the polymerase and exonuclease modes, by inducing a PCNA-polymerase complex configuration that favors synthesis over editing. This putative mechanism for fidelity control of replicative DNA polymerases is supported by experiments, in which mutations at the second interaction site caused enhancements in the exonuclease activity in the presence of PCNA.
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