Summary information and primary citation
- PDB-id
-
7kc0;
DSSR-derived features in text and
JSON formats
- Class
- replication
- Method
- cryo-EM (3.2 Å)
- Summary
- Structure of the saccharomyces cerevisiae replicative
polymerase delta in complex with a primer-template and the
pcna clamp
- Reference
-
Zheng F, Georgescu RE, Li H, O'Donnell ME (2020):
"Structure
of eukaryotic DNA polymerase delta bound to the PCNA
clamp while encircling DNA."
Proc.Natl.Acad.Sci.USA, 117,
30344-30353. doi: 10.1073/pnas.2017637117.
- Abstract
- The DNA polymerase (Pol) δ of <i>Saccharomyces
cerevisiae</i> (S.c.) is composed of the catalytic
subunit Pol3 along with two regulatory subunits, Pol31 and
Pol32. Pol δ binds to proliferating cell nuclear antigen
(PCNA) and functions in genome replication, repair, and
recombination. Unique among DNA polymerases, the Pol3
catalytic subunit contains a 4Fe-4S cluster that may sense
the cellular redox state. Here we report the 3.2-Å cryo-EM
structure of S.c. Pol δ in complex with primed DNA, an
incoming ddTTP, and the PCNA clamp. Unexpectedly, Pol δ
binds only one subunit of the PCNA trimer. This singular
yet extensive interaction holds DNA such that the 2-nm-wide
DNA threads through the center of the 3-nm interior channel
of the clamp without directly contacting the protein. Thus,
a water-mediated clamp and DNA interface enables the PCNA
clamp to "waterskate" along the duplex with minimum drag.
Pol31 and Pol32 are positioned off to the side of the
catalytic Pol3-PCNA-DNA axis. We show here that Pol31-Pol32
binds single-stranded DNA that we propose underlies
polymerase recycling during lagging strand synthesis, in
analogy to <i>Escherichia coli</i> replicase.
Interestingly, the 4Fe-4S cluster in the C-terminal CysB
domain of Pol3 forms the central interface to Pol31-Pol32,
and this strategic location may explain the regulation of
the oxidation state on Pol δ activity, possibly useful
during cellular oxidative stress. Importantly, human cancer
and other disease mutations map to nearly every domain of
Pol3, suggesting that all aspects of Pol δ replication are
important to human health and disease.
