PREDICTIVE MOTIFS DERIVED FROM CYTOSINE METHYLTRANSFERASES
PREDICTIVE MOTIFS DERIVED FROM CYTOSINE METHYLTRANSFERASES
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DOI：
10.1093/nar/17.7.2421
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发表时间：
1989-04-11
影响因子：
14.9
通讯作者：
ROBERTS, RJ
中科院分区：
文献类型：
--
作者：
POSFAI, J;BHAGWAT, AS;ROBERTS, RJ
13种细菌DNA甲基转移酶在特定DNA序列中催化5-甲基胞嘧啶的形成，具有相关的结构。相似的构建块（图案），包含不变的位置，可以在所有13个序列中以相同的顺序找到。其中5个块是高度保守的，另外5个块具有较弱的相似性。一个具有最不变残基的区块包含了所提议的催化位点的脯氨酸-半胱氨酸二肽。每个序列后半部分的一个区域在长度和序列组成上都异常多变。这些甲基转移酶在该区域表现出显著的同源性，在DNA识别中具有共同的特异性。这五个高度保守的基序可以用来区分已知的5-甲基胞嘧啶形成甲基转移酶与所有已知序列的其他甲基转移酶，以及PIR、GenBank和EMBL数据库中所有其他已鉴定的蛋白质。这五个基序发生在哺乳动物甲基转移酶中，负责在CG二肽中形成5-甲基胞嘧啶。通过搜索GenBank和EMBL数据库中未识别的开放阅读框，发现了两种可能形成5-甲基胞嘧啶的甲基转移酶。
Thirteen bacterial DNA methyltransferases that catalyze the formation of 5-methylcytosine within specific DNA sequences posses related structures. Similar building blocks (motifs), containing invariant positions, can be found in the same order in all thirteen sequences. Five of these blocks are highly conserved while a further five contain weaker similarities. One block, which has the most invariant residues, contains the proline-cysteine dipeptide of the proposed catalytic site. A region in the second half of each sequence is unusually variable both in length and sequence composition. Those methyltransferases that exhibit significant homology in this region share common specificity in DNA recognition. The five highly conesrved motifs can be used to discriminate the known 5-methylcytosine forming methyltransferases from all other methyltransferases of known sequence, and from all other identified proteins in the PIR, GenBank and EMBL databases. These five motifs occur in a mammalian methyltransferase responsible for the formationof 5-methylcytosine within CG dinulceotides. By searching the unidentified open reading frames present in the GenBank and EMBL databases, two potential 5-methylcytosine forming methyltransferases have been found.