Krüger D H, Schroeder C, Santibanez-Koref M, Reuter M
Institute of Medical Virology, Humboldt University School of Medicine, Charité, Berlin, German Democratic Republic.
Cell Biophys. 1989 Aug-Oct;15(1-2):87-95. doi: 10.1007/BF02991582.
The ocr+ gene of bacterial virus T7 codes for the first protein recognized to inhibit a specific group of DNA methylases. The recognition sequences of several other DNA methylases, not susceptible to Ocr inhibition, are significantly suppressed in the virus genome. The bacterial virus T3 encodes an Ado-Met hydrolase, destroying the methyl donor and causing T3 DNA to be totally unmethylated. These observations could stimulate analogous investigations into the regulation of DNA methylation patterns of eukaryotic viruses and cells. For instance, an underrepresentation of methylation sites (5'-CG) is also true for animal DNA viruses. Moreover, we were able to disclose some novel properties of DNA restriction-modification enzymes concerning the protection of DNA recognition sequences in which only one strand can be methylated (e.g., type III enzyme EcoP15) and the primary resistance of (unmethylated) DNA recognition sites towards type II restriction endonuclease EcoRII.
细菌病毒T7的ocr+基因编码了首个被确认可抑制特定DNA甲基化酶组的蛋白质。病毒基因组中，几种不受Ocr抑制的其他DNA甲基化酶的识别序列受到显著抑制。细菌病毒T3编码一种腺苷甲硫氨酸水解酶，该酶会破坏甲基供体，使T3 DNA完全未甲基化。这些观察结果可能会激发对真核病毒和细胞DNA甲基化模式调控的类似研究。例如，动物DNA病毒的甲基化位点（5'-CG）也存在低表达情况。此外，我们能够揭示DNA限制修饰酶的一些新特性，这些特性涉及对DNA识别序列的保护，其中只有一条链可以被甲基化（例如III型酶EcoP15），以及（未甲基化的）DNA识别位点对II型限制性内切酶EcoRII的主要抗性。
