RlmN and Cfr are radical SAM enzymes involved in methylation of ribosomal RNA.
RlmN and Cfr are radical SAM enzymes involved in methylation of ribosomal RNA.
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DOI：
10.1021/ja910850y
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发表时间：
2010-03-24
影响因子：
15
通讯作者：
Fujimori DG
中科院分区：
文献类型：
--
作者：
Yan F;LaMarre JM;Röhrich R;Wiesner J;Jomaa H;Mankin AS;Fujimori DG
核糖体RNA（rRNA）核苷酸的转录后修饰是调节核糖体功能和赋予细菌对核糖体靶向抗生素抗性的常见机制。一种这样的修饰是由固有甲基转移酶RlmN及其进化相关的抗性酶Cfr介导的核糖体的肽基转移酶中心内的腺苷核苷酸的甲基化。这些甲基转移酶催化甲基转移到复杂的23 S rRNA底物内的腺苷的芳族碳原子上，形成2，8-二甲基化产物。RlmN和Cfr是自由基SAM超家族的成员，并且含有特征性的富含半胱氨酸的CX 3CX 2C基序。我们证明，这两种酶都能够容纳所需的[4Fe-4S]簇。S-腺苷甲硫氨酸（SAM）既是甲基供体，也是5′-脱氧腺苷自由基的来源，5′-脱氧腺苷自由基激活底物进行甲基化。对rRNA需求的详细分析表明，这些酶可以利用无蛋白质的23 S rRNA作为底物，但不能利用完全组装的核糖体大亚基，这表明甲基化发生在核糖体组装过程中。23 S rRNA中的关键识别元件是螺旋90-92和包含A2503的相邻单链RNA。据我们所知，这项研究代表了自由基SAM超家族成员催化的甲基转移的第一个体外描述，它扩展了这个不同的酶类的催化库。此外，通过提供有关甲基化时间及其底物要求的信息，我们的研究结果对Cfr介导的rRNA修饰在获得抗生素抗性中的功能后果具有重要意义。
Posttranscriptional modifications of ribosomal RNA (rRNA) nucleotides are a common mechanism of modulating the ribosome’s function and conferring bacterial resistance to ribosome-targeting antibiotics. One such modification is methylation of an adenosine nucleotide within the peptidyl transferase center of the ribosome mediated by the indigenous methyltransferase RlmN and its evolutionary-related resistance enzyme Cfr. These methyltransferases catalyze methyl transfer to aromatic carbon atoms of the adenosine within a complex 23S rRNA substrate to form the 2,8-dimethylated product. RlmN and Cfr are members of the Radical SAM superfamily, and contain the characteristic cysteine rich CX3CX2C motif. We demonstrate that both enzymes are capable of accommodating the requisite [4Fe-4S] cluster. S-adenosylmethionine (SAM) is both the methyl donor and the source of a 5′-deoxyadenosyl radical, which activates the substrate for methylation. Detailed analyses of the rRNA requirements show that the enzymes can utilize protein-free 23S rRNA as a substrate, but not the fully-assembled large ribosomal subunit, suggesting that the methylations take place during the assembly of the ribosome. The key recognition elements in the 23S rRNA are helices 90–92 and the adjacent single stranded RNA that encompasses A2503. To our knowledge, this study represents the first in vitro description of a methyl transfer catalyzed by a member of Radical SAM superfamily, and it expands the catalytic repertoire of this diverse enzyme class. Furthermore, by providing information on both the timing of methylation and its substrate requirements, our findings have important implications for the functional consequences of Cfr-mediated modification of rRNA in acquisition of antibiotic resistance.
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影响因子：
7.8
作者：
Booker, Squire J.
通讯作者：
Booker, Squire J.
影响因子：
14.8
作者：
Chatterjee, Abhishek;Li, Yue;Zhang, Yang;Grove, Tyler L.;Lee, Michael;Krebs, Carsten;Booker, Squire J.;Begley, Tadhg P.;Ealick, Steven E.
通讯作者：
Ealick, Steven E.
影响因子：
4.8
作者：
Cicchillo, RM;Baker, MA;Booker, SJ
通讯作者：
Booker, SJ
影响因子：
15
作者：
Barckholtz, C;Barckholtz, TA;Hadad, CM
通讯作者：
Hadad, CM
DOI：
10.1073/pnas.0708608105
发表时间：
2008-02-12
影响因子：
11.1
作者：
Anton, Brian P.;Saleh, Lana;Roberts, Richard J.
通讯作者：
Roberts, Richard J.