TY - JOUR
T1 - Functions of base selection step in human DNA polymerase α
AU - Tanaka, Shigeru
AU - Cao, Ke
AU - Niimi, Atsuko
AU - Limsirichaikul, Siripan
AU - Miao, Huang Qin
AU - Nakamura, Noriko
AU - Murate, Takashi
AU - Hasegawa, Yoshinori
AU - Takahashi, Takashi
AU - Suzuki, Motoshi
PY - 2010/5/4
Y1 - 2010/5/4
N2 - Recent studies have revealed that the base selection step of DNA polymerases (pol) plays a role in prevention of DNA replication errors. We investigated whether base selection is required for the DNA replication fidelity of pol α and genomic stability in human cells. We introduced an Leu864 to Phe substitution (L864F) into human pol α and performed an in vitro LacZα forward mutation assay. Our results showed that the overall mutation rate was increased by 180-fold as compared to that of the wild-type. Furthermore, steady state kinetics analyses consistently showed that L864F pol α had a decreased discrimination ability between correct and incorrect nucleotide incorporation, as well as between matched and mismatched primer termini. L864F pol α also exhibited increased translesion activity over the abasic, etheno-A, O4-methyl-T, and O6-methyl-G sites. In addition, our steady state kinetics analyses supported the finding of increased translesion activity of L864F pol α over O6-methyl-G. We also established stable clones transfected with pola1L864F utilizing the human cancer cell line HCT116. Using the HPRT gene as a reporter, the spontaneous mutation rate of pola1L864F cells was determined to be 2.4-fold greater than that of wild-type cells. Mutation assays were also carried out using cells transiently transfected with the wild-type or pola1L864F, and increased mutant frequencies were observed in pola1L864F cells under both spontaneous and methyl methanesulfonate-induced conditions. Together, our results indicate that the base selection step in human pol α functions to prevent DNA replication errors and maintain genomic integrity in HCT116 cells.
AB - Recent studies have revealed that the base selection step of DNA polymerases (pol) plays a role in prevention of DNA replication errors. We investigated whether base selection is required for the DNA replication fidelity of pol α and genomic stability in human cells. We introduced an Leu864 to Phe substitution (L864F) into human pol α and performed an in vitro LacZα forward mutation assay. Our results showed that the overall mutation rate was increased by 180-fold as compared to that of the wild-type. Furthermore, steady state kinetics analyses consistently showed that L864F pol α had a decreased discrimination ability between correct and incorrect nucleotide incorporation, as well as between matched and mismatched primer termini. L864F pol α also exhibited increased translesion activity over the abasic, etheno-A, O4-methyl-T, and O6-methyl-G sites. In addition, our steady state kinetics analyses supported the finding of increased translesion activity of L864F pol α over O6-methyl-G. We also established stable clones transfected with pola1L864F utilizing the human cancer cell line HCT116. Using the HPRT gene as a reporter, the spontaneous mutation rate of pola1L864F cells was determined to be 2.4-fold greater than that of wild-type cells. Mutation assays were also carried out using cells transiently transfected with the wild-type or pola1L864F, and increased mutant frequencies were observed in pola1L864F cells under both spontaneous and methyl methanesulfonate-induced conditions. Together, our results indicate that the base selection step in human pol α functions to prevent DNA replication errors and maintain genomic integrity in HCT116 cells.
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U2 - 10.1016/j.dnarep.2010.02.002
DO - 10.1016/j.dnarep.2010.02.002
M3 - Article
C2 - 20202915
AN - SCOPUS:77952101773
SN - 1568-7864
VL - 9
SP - 534
EP - 541
JO - DNA Repair
JF - DNA Repair
IS - 5
ER -
