Summary information and primary citation
- PDB-id
-
6as7;
DSSR-derived features in text and
JSON formats
- Class
- replication-DNA
- Method
- X-ray (2.95 Å)
- Summary
- Crystal structure of the catalytic core of human DNA
polymerase alpha in ternary complex with an DNA-primed DNA
template and dctp
- Reference
-
Baranovskiy AG, Duong VN, Babayeva ND, Zhang Y, Pavlov
YI, Anderson KS, Tahirov TH (2018): "Activity
and fidelity of human DNA polymerase alpha depend on
primer structure." J. Biol. Chem.,
293, 6824-6843. doi: 10.1074/jbc.RA117.001074.
- Abstract
- DNA polymerase α (Polα) plays an important role in
genome replication. In a complex with primase, Polα
synthesizes chimeric RNA-DNA primers necessary for
replication of both chromosomal DNA strands. During RNA
primer extension with deoxyribonucleotides, Polα needs to
use double-stranded helical substrates having different
structures. Here, we provide a detailed structure-function
analysis of human Polα's interaction with dNTPs and DNA
templates primed with RNA, chimeric RNA-DNA, or DNA. We
report the crystal structures of two ternary complexes of
the Polα catalytic domain containing dCTP, a DNA template,
and either a DNA or an RNA primer. Unexpectedly, in the
ternary complex with a DNA:DNA duplex and dCTP, the
"fingers" subdomain of Polα is in the open conformation.
Polα induces conformational changes in the DNA and hybrid
duplexes to produce the universal double helix form.
Pre-steady-state kinetic studies indicated for both duplex
types that chemical catalysis rather than product release
is the rate-limiting step. Moreover, human Polα extended
DNA primers with higher efficiency but lower processivity
than it did with RNA and chimeric primers. Polα has a
substantial propensity to make errors during DNA synthesis,
and we observed that its fidelity depends on the type of
sugar at the primer 3'-end. A detailed structural
comparison of Polα with other replicative DNA polymerases
disclosed common features and some differences, which may
reflect the specialization of each polymerase in genome
replication.
