Janion Celina
Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 5A Pawińskiego St., 02-106 Warszawa, Poland.
Postepy Biochem. 2006;52(3):239-46.
Methylating agents belong to mutagens occurring most frequently in our environment. They methylate mainly the nitrogen bases in DNA and RNA, affecting their functions. In E. coli the alkylated bases are repaired by proteins and enzymes either permanently present in the cells (Ogt, Ada) or produced transiently (Ada, AlkB, AlkA, Aid), after induction of the Ada defence system. Alkylating agents induce also the SOS system, which enhances the synthesis of about 40 proteins, including those participating in recombination, replication and mutagenesis of DNA. All DNA interactions, modifications and repairs constitute an amazing and highly efficiently functioning cellular system. Among the repair proteins there are some which affect the alkylated bases in a non-conventional way, very rarely occurring in nature. Especially amazing is the mechanism of action of dioxogenase AlkB, which combines the repair of methyl-, ethyl- and etheno-base derivatives with oxidation and dissociation of the modified groups, leading to direct recovery of natural bases. This review attempts to elucidate the role of the individual proteins involved in the repair processes.
甲基化剂属于我们环境中最常见的诱变剂。它们主要使DNA和RNA中的氮碱基甲基化，从而影响其功能。在大肠杆菌中，烷基化碱基由细胞中永久存在的蛋白质和酶（Ogt、Ada）或在诱导Ada防御系统后瞬时产生的蛋白质和酶（Ada、AlkB、AlkA、Aid）进行修复。烷基化剂还会诱导SOS系统，该系统会增强约40种蛋白质的合成，包括参与DNA重组、复制和诱变的蛋白质。所有的DNA相互作用、修饰和修复构成了一个惊人且高效运作的细胞系统。在修复蛋白中，有些以非传统方式影响烷基化碱基，这种方式在自然界中很少见。特别令人惊奇的是双加氧酶AlkB的作用机制，它将甲基、乙基和乙烯基碱基衍生物的修复与修饰基团的氧化和解离相结合，直接恢复天然碱基。这篇综述试图阐明参与修复过程的各个蛋白质的作用。
