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Y. Li, S. Korolev, and G. Waksman.
Crystal structures of open and closed forms of binary and ternary complexes of
the large fragment of Thermus aquaticus DNA polymerase I: structural basis of nucleotide
incorporation
EMBO Journal. 17:7514-7525. (1998)
The crystal structures of two ternary
complexes of the large fragment of Thermus aquaticus DNA polymerase I
(Klentaq1) with a primer/template DNA and dideoxycytidine triphosphate and that
of a binary complex of the same enzyme with a primer/template DNA were
determined to a resolution of 2.3, 2.3 and 2.5 Angstrom, respectively. One
ternary complex structure differs markedly from the two other structures by a
large reorientation of the tip of the fingers domain. This structure, designated
"closed", represents the ternary polymerase complex caught in the act
of incorporating a nucleotide. In the two other structures, the tip of the
fingers domain is rotated outward by 46 degree ("open") and this
orientation of the fingers domain is similar to that of the apo form of
Klentaq1. These structures provide the first direct evidence in DNA polymerase
I enzymes for a large conformational change responsible for assembling an
active ternary complex.