van Buul C P, van Knippenberg P H
Gene. 1985;38(1-3):65-72. doi: 10.1016/0378-1119(85)90204-5.
The ksgA gene of Escherichia coli encodes a methyltransferase (MeT) that specifically dimethylates two adjacent adenosines near the 3' end of 16S RNA in the 30S particle. Its inactivation leads to kasugamycin (Ksg) resistance. Several plasmids were constructed with inserts which complemented chromosomal ksgA mutations. One of these inserts was sequenced and found to contain an open reading frame (ORF) sufficient to code for the previously identified 30-kDal MeT. We have compared the amino acid (aa) sequence of the ksgA-encoded enzyme with three published sequences of MeT involved in dimethylation of an adenosine residue in 23S RNA and rendering the organisms resistant to the MLS antibiotics. The homologous patches in the sequences of all four enzymes suggest that those might correspond to contact points for the common substrates, e.g., for the adenosine residue(s) and S-adenosylmethionine (SAM).
大肠杆菌的ksgA基因编码一种甲基转移酶（MeT），该酶能特异性地使30S颗粒中16S RNA 3'端附近的两个相邻腺苷二甲基化。其失活会导致对春日霉素（Ksg）产生抗性。构建了几个含有能互补染色体ksgA突变的插入片段的质粒。对其中一个插入片段进行测序，发现其包含一个足以编码先前鉴定的30-kDal MeT的开放阅读框（ORF）。我们将ksgA编码酶的氨基酸（aa）序列与参与23S RNA中腺苷残基二甲基化并使生物体对MLS抗生素产生抗性的三种已发表的MeT序列进行了比较。所有四种酶序列中的同源区域表明，这些区域可能对应于常见底物的接触点，例如腺苷残基和S-腺苷甲硫氨酸（SAM）。
