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Proc Natl Acad Sci U S A. Sep 26, 1995; 92(20): 9264–9268.

Crystal structure of the large fragment of Thermus aquaticus DNA polymerase I at 2.5-A resolution: structural basis for thermostability.


The crystal structure of the large fragment of the Thermus aquaticus DNA polymerase (Klentaq1), determined at 2.5-A resolution, demonstrates a compact two-domain architecture. The C-terminal domain is identical in fold to the equivalent region of the Klenow fragment of Escherichia coli DNA polymerase I (Klenow pol I). Although the N-terminal domain of Klentaq1 differs greatly in sequence from its counterpart in Klenow pol I, it has clearly evolved from a common ancestor. The structure of Klentaq1 reveals the strategy utilized by this protein to maintain activity at high temperatures and provides the structural basis for future improvements of the enzyme.

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