Absence of methylation at HpaII sites in three human genomic tRNA sequences.
Absence of methylation at HpaII sites in three human genomic tRNA sequences.
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三个人类基因组 tRNA 序列中 HpaII 位点不存在甲基化。
DOI：
10.1093/nar/18.23.6965
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发表时间：
1990
影响因子：
14.9
通讯作者：
Gartler,SM
中科院分区：
文献类型：
--
作者：
Schorderet,DF;Gartler,SM
自从最近邻分析的发展以来，人们已经知道二核苷酸CpG的频率在脊椎动物DNA中被显著抑制（即小于%C × ×G）。这种抑制似乎是异质性的，因为几年前显示三种脊椎动物tRNA基因没有表现出CpG抑制。我们分析了13种不同的人类tRNA基因，发现它们也不表现出CpG抑制。由于CpG抑制至少在某种程度上与甲基化脱氨基过程有关，甲基化的CpG通过该过程突变为TpG，因此我们研究了tRNA中CpG抑制的缺乏是否源于甲基化的缺乏。（赖氨酸、脯氨酸和苯丙氨酸），并通过聚合酶链反应（PCR）和Southern印迹分析检查Hpall位点的甲基化。观察到的模式是一致的甲基化的情况下，在7个Hpall网站分析和周围的tRNA基因，我们预测，在这些基因中的剩余的CpG将是未甲基化。由于富含GC的启动子区域也逃脱CpG抑制，并且由于它们通常是未甲基化的，因此避免甲基化可能是脊椎动物基因组的选定区域中不存在CpG抑制的一般解释。
It has been known since the development of nearest neighbor analysis that the frequency of the dinucleotide CpG is markedly suppressed in vertebrate DNA (i.e. less than %C × ×G). This suppression appears to be heterogeneous since it was shown some years ago that three vertebrate tRNA genes did not exhibit CpG suppression. We have analyzed 13 different human tRNA genes and found that they also do not exhibit CpG suppression. Because CpG suppression has been linked, to some extent at least, to the methylationdeamination process by which a methylated CpG is mutated to TpG, we investigated whether the lack of suppression of CpG in tRNAs could originate from anabsence of methylation.Three human tRNA genes were selected from Genbank (Lysine, Proline, and Phenylalanine) and examined for methylation at Hpall sites by polymerase chain reaction (PCR) and Southern blot analysis. The observed patterns were consistent with the absence of methylation at the seven Hpall sites analyzed in and around the tRNA genes, and we predict that the remaining CpGs in these genes will be unmethylated. Since GC-rich promoter regions also escape CpG suppression and since they are generally unmethylated, avoidance of methylation may be a general explanation for the absence of CpG suppression in selected regions of vertebrate genomes.