Replication Error Rates for G·dGTP, T·dGTP, and A·dGTP Mispairs and Evidence for Differential Proofreading by Leading and Lagging Strand DNA Replication Complexes in Human Cells (*)-猫眼课题宝

G·dGTP、T·dGTP 和 A·dGTP 错配的复制错误率以及通过人体细胞中前导链和滞后链 DNA 复制复合物进行差异校对的证据 (*)

DOI：

发表时间：

1995

期刊：

Journal of Biological Chemistry

影响因子：

4.8

通讯作者：

中科院分区：

生物学2区

文献类型：

作者：

S. Izuta;John D. Roberts;T. Kunkel

We have determined the fidelity of DNA replication by human cell extracts in reactions containing excess dGTP. Replication errors were scored using two M13 DNA substrates having the replication origin on opposite sides of the lacZ α-complementation gene. The data suggest that the average rates for replication errors resulting from G(template), T•dGTP, and A•dGTP mispairs are 25 × 10−6, 12 × 10−6, and 3 × 10−6, respectively. The data also suggest that error rates for both the (+) and(-) strands differ by less than 2-fold when they are replicated either as the leading or lagging strand. This is in contrast to the 33- and 8-fold differences observed earlier for G•dTTP and C•dTTP mispairs on the (+) strand when replicated by the leading or lagging strand complex (Roberts, J. D., Izuta, S., Thomas, D. C., and Kunkel, T. A.(1994) J. Biol. Chem. 269, 1711-1717). Thus, the relative fidelity of the leading and lagging strand replication proteins varies with the mispair and sequence considered. Misincorporation of dGTP preferentially occurs at template positions where dGTP is the next correct nucleotide to be incorporated. This “next nucleotide” effect is characteristic of reduced exonucleolytic proofreading and suggests that these replication errors are normally proofread efficiently. Fidelity measurements performed in the absence or presence of dGMP, an inhibitor of proofreading exonuclease activity, suggest that the leading strand replication complex proofreads some mispairs more efficiently than does the lagging strand replication complex.