Preferential repair incision of cross-links versus monoadducts in psoralen-damaged plasmid DNA by human cell-free extracts.
Preferential repair incision of cross-links versus monoadducts in psoralen-damaged plasmid DNA by human cell-free extracts.
复制标题
通过人无细胞提取物优先修复补骨脂素损伤的质粒 DNA 中的交联切口与单加合物。
DOI：
10.1021/bi9607261
复制
发表时间：
1996
期刊：
影响因子：
2.9
通讯作者：
B. Salles
中科院分区：
文献类型：
--
作者：
P. Calsou;E. Sage;E. Moustacchi;B. Salles
Upon UVA irradiation psoralens covalently bind to DNA as monoadduct and interstrand crosslink. Psoralen photoadducts are processed via an excision repair reaction that has been reproduced in vitro with transcriptionnally active cell-free extracts. A derived in vitro assay that allows direct quantification of the incised sites has been set up and used to compare the efficiency of the incision reaction on monoadducts and interstrand cross-links. The incision reaction was performed with HeLa cell-free extracts on angelicin or 8-methoxypsoralen (8-MOP)-modified plasmid DNA substrates carrying known amounts of mono- and biadducts, within various relative ratios. In the case of 8-MOP modified plasmids consisting in a mixture of mono- and biadducts on the same DNA molecule, the incision signal was mainly due to the presence of interstrand cross-links. The extent of incision was linear with the number of cross-links up to about 4 cross-links per plasmid and then reached a plateau. The sensitivity of incision defined as the increase of incision by 2-fold over the background level corresponded to about 1 cross-link per plasmid molecule, and about 7% of the total cross-links were repaired under our assay conditions. The incision activity on angelicin monoadducts yielded only 27% when compared to that on 8-MOP cross-links. Furthermore, 8-MOP cross-links lowered the incision extent of angelicin monoadducts when the two photoadducts were present on distinct plasmid DNA molecules. These data are in line with the more rapid excision of psoralen interstrand cross-links vs monoadducts observed in vivo.
