Reduced misreading of asparagine codons by Escherichia coli tRNALys with hypomodified derivatives of 5-methylaminomethyl-2-thiouridine in the wobble position
Reduced misreading of asparagine codons by Escherichia coli tRNALys with hypomodified derivatives of 5-methylaminomethyl-2-thiouridine in the wobble position
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DOI：
10.1006/jmbi.1998.2162
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发表时间：
1998-11-20
影响因子：
5.6
通讯作者：
McCloskey, JA
中科院分区：
文献类型：
--
作者：
Hagervall, TG;Pomerantz, SC;McCloskey, JA
有人提出，xm（5）（s（2））U（m）34型修饰的核苷限制了碱基的摆动能力，它们的功能是防止编码两种不同氨基酸的混合密码子家族盒中密码子第三位的误读。在这项研究中，在大肠杆菌中，在体内的天冬酰胺密码子在噬菌体MS 2 mRNA的不同的低修饰衍生物的tRNA（赖氨酸），通常含有5-甲基氨基甲基-2-硫代尿苷（mnm（5）s（2）U34）的摆动位置，已被误读进行了分析。与mnm（5）s（2）U功能的一般假设所预测的相反，发现tRNA（Lys）对天冬酰胺密码子的误读在mnmA（以前称为asuE或trmU）和mnmE（以前称为trmE）突变体中大大减少，它们分别含有低修饰的mnm（5）U 34和s（2）U 34，而不是完全修饰的mnm 5s 2U 34。此外，发现在所采用的生长条件下，这些低修饰的tRNA在体内有效地装载赖氨酸。后一结果与体外获得的结果不一致。结果进行了讨论，有关的xm（5）s（2）U型修饰核苷的假设功能。(C)北京：科学出版社.
It has been suggested that modified nucleosides of the xm(5)(s(2))U(m)34-type restrict the wobble capacity of the base, and that their function is to prevent misreading in the third position of the codon in mixed codon family boxes that encode two different amino acids. In this study in Escherichia coli, the misreading in vivo of asparagine codons in bacteriophage MS2 mRNA by different hypomodified derivatives of tRNA(Lys), normally containing 5-methylaminomethyl-2-thiouridine (mnm(5)s(2)U34) in the wobble position, has been analysed. Contrary to what would be predicted from the general hypothesis for the function of mnm(5)s(2)U, it was found that the misreading of asparagine codons by tRNA(Lys) was greatly reduced in the mnmA (formerly asuE or trmU) and mnmE (formerly trmE) mutants which contain the hypomodified mnm(5)U34 and s(2)U34, respectively, instead of the fully modified mnm5s2U34. In addition, it was found that these hypomodified tRNAs were efficiently charged with lysine in vivo, under the growth conditions employed. The latter result is at variance with results obtained in vitro. The results are discussed in relation to the postulated function for modified nucleosides of the xm(5)s(2)U type. (C) 1998 Academic Press.