Inventors:
Steven Evans - Gosforth, GB
Joseph Anthony Mamone - Somerset NJ
Maria Davis - Princeton NJ
Bernard A. Connolly - Kingston Park, GB
Assignee:
Amersham Pharmacia Biotech, Inc. - Piscataway NJ
International Classification:
C12N 912
C12N 900
C12P 1934
C07K 100
C07H 2104
Abstract:
Polymerases from the Pol I family which are able to efficiently use ddNTPs have demonstrated a much improved performance when used to sequence DNA. A number of mutations have been made to the gene coding for the Pol II family DNA polymerase from the archaeon Pyrococcus furiosus with the aim of improving ddNTP utilisation. "Rational" alterations to amino acids likely to be near the dNTP binding site (based on sequence homologies and structural information) did not yield the desired level of selectivity for ddNTPs. However, alteration at four positions (Q472, A486, L490 and Y497) gave rise to variants which incorporated ddNTPs better than the wild type, allowing sequencing reactions to be carried out at lowered ddNTP:dNTP ratios. Wild type Pfu-Pol required a ddNTP:dNTP ratio of 30:1; values of 5:1 (Q472H), 1:3 (L490Y), 1:5 (A486Y) and 5:1 (Y497A) were found with the four mutants; A486Y representing a 150-fold improvement over the wild type. A486, L490 and Y407 are on an. alpha.