Structural basis for hypermodification of the wobble uridine in tRNA by bifunctional enzyme MnmC.
Structural basis for hypermodification of the wobble uridine in tRNA by bifunctional enzyme MnmC.
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DOI：
10.1186/1472-6807-13-5
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发表时间：
2013-04-24
影响因子：
--
通讯作者：
Almo SC
中科院分区：
文献类型：
--
作者：
Kim J;Almo SC
在大肠杆菌中观察到对谷氨酸、赖氨酸和精氨酸特异性的tRNA的摆动位置处的尿苷或2-硫代尿苷（mnm 5 U34或mnm 5s 2U 34）的甲基氨基甲基修饰，并且允许特异性识别以A或G结尾的密码子。在负责这种转录后修饰的生物合成途径中，双功能酶MnmC催化其高度修饰的底物羧甲基氨基甲基尿苷（cmnm 5 U34）转化为mnm 5 U34。MnmC催化黄素腺嘌呤二核苷酸（FAD）依赖性的羧甲基基团从cmnm 5 U34经由亚胺中间体的氧化裂解以生成氨甲基尿苷（nm 5 U34），其随后被S-腺苷-L-甲硫氨酸（SAM）甲基化以生成甲基氨甲基尿苷（mnm 5 U34）。SAM/FAD结合的双功能MnmC从大肠杆菌和鼠疫耶尔森氏菌，和FAD结合的双功能MnmC从鼠疫耶尔森氏菌的X-射线晶体结构进行了测定，并在体外试验中验证的催化功能。来自两种革兰氏阴性细菌的MnmC的晶体结构揭示了酶的整体结构和两个独立催化结构域的相对配置：含有SAM结合位点的Rossmann折叠结构域和含有结构上与来自枯草芽孢杆菌的甘氨酸氧化酶同源的结构域的FAD。MnmC的结构也揭示了详细的原子相互作用在域间界面，并提供相关的整体催化机制的空间限制。
Methylaminomethyl modification of uridine or 2-thiouridine (mnm5U34 or mnm5s2U34) at the wobble position of tRNAs specific for glutamate, lysine and arginine are observed in Escherichia coli and allow for specific recognition of codons ending in A or G. In the biosynthetic pathway responsible for this post-transcriptional modification, the bifunctional enzyme MnmC catalyzes the conversion of its hypermodified substrate carboxymethylaminomethyl uridine (cmnm5U34) to mnm5U34. MnmC catalyzes the flavin adenine dinucleotide (FAD)-dependent oxidative cleavage of carboxymethyl group from cmnm5U34 via an imine intermediate to generate aminomethyl uridine (nm5U34), which is subsequently methylated by S-adenosyl-L-methionine (SAM) to yield methylaminomethyl uridine (mnm5U34). The X-ray crystal structures of SAM/FAD-bound bifunctional MnmC from Escherichia coli and Yersinia pestis, and FAD-bound bifunctional MnmC from Yersinia pestis were determined and the catalytic functions verified in an in vitro assay. The crystal structures of MnmC from two Gram negative bacteria reveal the overall architecture of the enzyme and the relative disposition of the two independent catalytic domains: a Rossmann-fold domain containing the SAM binding site and an FAD containing domain structurally homologous to glycine oxidase from Bacillus subtilis. The structures of MnmC also reveal the detailed atomic interactions at the interdomain interface and provide spatial restraints relevant to the overall catalytic mechanism.
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DOI：
10.1107/s0907444904019158
发表时间：
2004-12-01
影响因子：
2.2
作者：
Emsley, P;Cowtan, K
通讯作者：
Cowtan, K
影响因子：
2.9
作者：
Jamil, Farrukh;Gardner, Qurra-tul-Ann Afza;Akhtar, Muhammad
通讯作者：
Akhtar, Muhammad
影响因子：
14.9
作者：
Jühling F;Mörl M;Hartmann RK;Sprinzl M;Stadler PF;Pütz J
通讯作者：
Pütz J
影响因子：
2.9
作者：
Kambampati, R;Lauhon, CT
通讯作者：
Lauhon, CT
影响因子：
4.8
作者：
Boehme, Sabine;Meyer, Simon;Klare, Johann P.
通讯作者：
Klare, Johann P.