Y. Li, Y. Kong, S. Korolev, and G. Waksman.
Crystal structures of the
Klenow fragment of Thermus aquaticus DNA polymerase I complexed with
deoxyribonucleoside triphosphates.
Protein Science. In Press. (1998)
The crystal structures of the Klenow fragment of the Thermus aquaticus DNA
polymerase I (Klentaq1) complexed with four deoxyribonucleoside triphosphates
(dNTP) have been determined to 2.5 resolution. The dNTPs bind adjacent to the O
helix of Klentaq1. The triphosphate moieties are at nearly identical positions in all
four complexes and are anchored by three positively charged residues, Arg659,
Lys663 and Arg587, and by two polar residues, His639 and Gln613. The configuration
of the base moieties in the Klentaq1/dNTP complexes demonstrates variability
suggesting that dNTP binding is primarily determined by recognition and binding of
the phosphate moiety. However, when superimposed on the Taq polymerase /
blunt end DNA complex structure (Eom et al., 1996), two of the dNTP / Klentaq1
structures demonstrate appropriate stacking of the nucleotide base with the 3' end of
the DNA primer strand, suggesting that at least in these two binary complexes, the
observed dNTP conformations are functionally relevant.
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