Site-specific mutagenesis in Escherichia coli by N2-deoxyguanosine adducts derived from the highly carcinogenic fjord-region benzo[c]phenanthrene 3,4-diol 1,2-epoxides.
Site-specific mutagenesis in Escherichia coli by N2-deoxyguanosine adducts derived from the highly carcinogenic fjord-region benzo[c]phenanthrene 3,4-diol 1,2-epoxides.
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源自高致癌性峡湾地区苯并[c]菲 3,4-二醇 1,2-环氧化物的 N2-脱氧鸟苷加合物对大肠杆菌进行定点诱变。
DOI：
10.1021/tx020073r
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发表时间：
2002
影响因子：
4.1
通讯作者：
Jerina,DonaldM
中科院分区：
文献类型：
--
作者：
Ramos,LeilaniA;Ponten,Ingrid;Dipple,Anthony;Kumar,Subodh;Yagi,Haruhiko;Sayer,JaneM;Kroth,Heiko;Kalena,Govind;Jerina,DonaldM
虽然已经有大量关于苯并[a]芘二醇环氧化物(B[a]P DES)的dGuo加合物(B[a]P Des)定点突变的研究，但本研究是高致癌性苯并[c]菲3，4-二醇1，2-环氧化物(B[c]Ph Des)的dGo加合物定点突变的第一个例子。由dGuo的N-氨基在C-1上顺式和反式打开B[c]Ph Des的四个光学活性异构体得到的八个加合物在下划线的位置被结合到5‘-TTCGAATCCTTCCCCC(上下文III)和5’-GGGGTTCCCGAGCGGC(上下文IV)。将这些修饰的寡核苷酸和未修饰的对照连接到单链M13mp7L2中，然后将其转化到SOS诱导的大肠杆菌中，在两种序列背景下复制病变后，通过差异杂交对后代进行突变分析。对于16个加合物，突变频率变化超过2个数量级，分布合理均匀(3个加合物的突变频率为0.4−1%，6个加合物的突变频率为1−2%，5个加合物的突变频率为3−7.4%，11和39%各有1个加合物)。除了这最后一个加合物外，所有B[c]Ph DE加合物的突变频率都低于相同序列中具有相同立体化学的B[a]P类似物的突变频率。在烃与dGuo碱基结合部位含有S构型加合物的载体，其主要碱基替换是G→T，其次是G→A。相反，对于含有R构型加合物的载体，主要碱基替换是G→A。提出了这种差异的可能的结构基础。
Although there have been numerous studies of site-specific mutagenesis by dGuo adducts of benzo[a]pyrene diol epoxides (B[a]P DEs), the present study represents the first example of site-specific mutagenesis by dGuo adducts of the highly carcinogenic benzo[c]phenanthrene 3,4-diol 1,2-epoxides (B[c]Ph DEs). The eight adducts that would result from cis- and trans-opening at C-1 of four optically active isomers of B[c]Ph DEs by theN2-amino group of dGuo were incorporated into 5‘-TTCGAATCCTTCCCCC (context III) and 5‘-GGGGTTCCCGAGCGGC (context IV) at the underlined site. These modified oligonucleotides along with unmodified controls were ligated into single-stranded M13mp7L2, which were then used to transfect SOS-inducedEscherichia coli.Upon replication of the lesions in each of the two sequence contexts, mutational analysis of the progeny was performed by differential hybridization. For the 16 adducts, the mutation frequencies varied over 2 orders of magnitude with a reasonably even distribution (0.4−1% for three adducts, 1−2% for six adducts, 3−7.4% for five adducts, and one adduct each at 11 and 39%). For all but this last adduct, the mutation frequency for a given B[c]Ph DE adduct was less than for its B[a]P analogue with the same stereochemistry in the same sequence. For the vectors containing adducts withSconfiguration at the site of attachment of the hydrocarbon to the dGuo base, the main base substitution was G → T followed by G → A. In contrast, for the vectors containing adducts withRconfiguration, the main base substitution was G → A. The most notable observation in the present study is the low frequency of mutations induced by the B[c]Ph DE-dGuo adducts relative to their B[a]P counterparts. A possible structural basis for this difference is proposed.