Crystal structure of RImAI:: Implications for understanding the 23S rRNA G745/G748-methylation at the macrolide antibiotic-binding site
Crystal structure of RImAI:: Implications for understanding the 23S rRNA G745/G748-methylation at the macrolide antibiotic-binding site
复制标题
DOI：
10.1073/pnas.0400189101
复制
发表时间：
2004-03-23
影响因子：
11.1
通讯作者：
Montelione, GT
中科院分区：
文献类型：
--
作者：
Das, K;Acton, T;Montelione, GT
RImA类酶（RImA（I）和RImA（II））催化23 S rRNA的发夹35的鸟嘌呤碱基（革兰氏阴性细菌中的G745和革兰氏阳性细菌中的G748）的N1-甲基化。我们已经确定了大肠杆菌RIMA（I）的晶体结构在2.8埃分辨率，提供了三维结构信息的RIMA类的RNA甲基转移酶。二聚体蛋白质结构的特点，提供了新的见解，其分子功能。每个RIMA（I）分子具有负责其rRNA底物的特异性识别和结合的Zn结合结构域和甲基转移酶结构域。在晶体结构中观察到的不对称RIMA（I）二聚体具有明确的W形RNA结合裂缝。两个S-腺苷-L-甲硫氨酸底物分子位于W形RNA结合裂缝的两个山谷处。与已知的RNA结合蛋白不同，RNA结合裂缝的独特形状是高度特异性的，并且在结构上补充了细菌23 S rRNA的发夹35的3D结构。除了发夹35之外，发夹33和34的部分也与RIMA（I）二聚体相互作用。
The RImA class of enzymes (RImA(I) and RImA(II)) catalyzes N1-methylation of a guanine base (G745 in Gram-negative and G748 in Gram-positive bacteria) of hairpin 35 of 23S rRNA. We have determined the crystal structure of Escherichia coli RImA(I) at 2.8-Angstrom resolution, providing 3D structure information for the RImA class of RNA methyltransferases. The dimeric protein structure exhibits features that provide new insights into its molecular function. Each RImA(I) molecule has a Zn-binding domain, responsible for specific recognition and binding of its rRNA substrate, and a methyltransferase domain. The asymmetric RImA(I) dimer observed in the crystal structure has a well defined W-shaped RNA-binding cleft. Two S-adenosyl-L-methionine substrate molecules are located at the two valleys of the W-shaped RNA-binding cleft. The unique shape of the RNA-binding cleft, different from that of known RNA-binding proteins, is highly specific and structurally complements the 3D structure of hairpin 35 of bacterial 23S rRNA. Apart from the hairpin 35, parts of hairpins 33 and 34 also interact with the RImA(I) dimer.