Behrens B, Noyer-Weidner M, Pawlek B, Lauster R, Balganesh T S, Trautner T A
EMBO J. 1987 Apr;6(4):1137-42. doi: 10.1002/j.1460-2075.1987.tb04869.x.
B. subtilis phage rho 11s codes for a multispecific DNA methyltransferase (Mtase) which methylates cytosine within the sequences GGCC and GAGCTC. The Mtase gene of rho 11s was isolated and sequenced. It has 1509 bp, corresponding to 503 amino acids (aa). The enzyme's Mr of 57.2 kd predicted from the nucleotide sequence was verified by direct Mr determinations of the Mtase. A comparison of the aa sequence of the rho 11s Mtase with those of related phages SPR and phi 3%, which differ in their methylation potential, revealed generalities in the building plan of such enzymes. At least 70% of the aa of each enzyme are contained in two regions of 243 and 109 aa at the N and C termini respectively, which are highly conserved among the three enzymes. In each enzyme, variable sequences separate the conserved regions. Variability is generated through the single or multiple use of related and unrelated sequence motifs. We propose that the recognition of those DNA target sequences, which are unique for each of the three enzymes, is determined by these variable regions. Evolutionary relationships between the three enzymes are discussed.
枯草芽孢杆菌噬菌体rho 11s编码一种多特异性DNA甲基转移酶（Mtase），该酶可使GGCC和GAGCTC序列中的胞嘧啶甲基化。rho 11s的Mtase基因被分离并测序。它有1509个碱基对，对应503个氨基酸（aa）。通过对Mtase的直接分子量测定，验证了根据核苷酸序列预测的该酶57.2 kd的分子量。对rho 11s Mtase与相关噬菌体SPR和phi 3%的氨基酸序列进行比较，这两种噬菌体在甲基化潜力上有所不同，结果揭示了此类酶构建模式的共性。每种酶至少70%的氨基酸分别包含在N端和C端的两个区域，即243个氨基酸和109个氨基酸的区域，这三个酶之间高度保守。在每种酶中，可变序列分隔了保守区域。变异性是通过相关和不相关序列基序的单次或多次使用产生的。我们认为，这三种酶各自特有的那些DNA靶序列的识别是由这些可变区域决定的。讨论了这三种酶之间的进化关系。
