Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA.
Arch Biochem Biophys. 2011 Sep 15;513(2):81-6. doi: 10.1016/j.abb.2011.07.004. Epub 2011 Jul 18.
Microorganisms are exposed to a wide variety of exogenous and endogenous chemical agents that alkylate DNA. Escherichia coli cells exhibit an adaptive response that recognizes and repairs alkylated DNA lesions using Ada, AlkA, and AlkB enzymes. Another alkylation response protein, the DNA-binding flavoprotein AidB, was proposed to repair DNA or protect it from chemical alkylating agents, but direct evidence for its role is lacking. Here, AidB was shown to form tight complexes with both flavodoxin and acyl carrier protein. In addition, electron transfer between 1-electron and 2-electron reduced flavodoxin to oxidized AidB was observed, although with very small rate constants. AidB was found to bind to RNA, raising the prospect that the protein may have a role in protection of RNA from chemical alkylation. Finally, the reagent N-methyl-N'-nitro-N-nitrosoguanidine was eliminated as a direct substrate of the enzyme.
微生物暴露于多种外源和内源性化学试剂中，这些化学试剂会使 DNA 烷基化。大肠杆菌细胞表现出一种适应性反应，利用 Ada、AlkA 和 AlkB 酶识别和修复烷基化的 DNA 损伤。另一种烷基化反应蛋白，DNA 结合黄素蛋白 AidB，被提议用于修复 DNA 或保护其免受化学烷化剂的侵害，但缺乏其作用的直接证据。在这里，AidB 被证明与黄素蛋白和酰基辅酶 A 形成紧密的复合物。此外，观察到单电子和双电子还原的黄素蛋白与氧化 AidB 之间的电子转移，尽管速率常数非常小。发现 AidB 与 RNA 结合，这增加了该蛋白可能在保护 RNA 免受化学烷化作用方面发挥作用的可能性。最后，试剂 N-甲基-N'-硝基-N-亚硝基胍被排除为该酶的直接底物。
