Features of 80S mammalian ribosome and its subunits
Features of 80S mammalian ribosome and its subunits
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DOI：
10.1093/nar/gkn424
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发表时间：
2008-08-01
影响因子：
14.9
通讯作者：
Nierhaus, Knud H.
中科院分区：
文献类型：
--
作者：
Budkevich, Tatyana V.;El'skaya, Anna V.;Nierhaus, Knud H.
一般认为核糖体功能的基本特征是普遍有效的，但系统的测试仍然突出了更高真核80S核糖体。在这里，我们报告：(i)真核生物和细菌核糖体及其亚基的tRNA和mRNA结合能力的差异。真核生物的40S亚基仅在同源tRNA存在时结合mRNA，而细菌的30S在tRNA不存在时也结合mRNA。80S核糖体在缺乏tRNA的情况下能有效结合mRNA。相比之下，细菌70S在tRNA存在时比在tRNA不存在时更有效地与mRNA相互作用。（ii）检查核糖体的起始（P-i），前易位（PRE）和后易位（POST）状态，包括A和E位点之间的互连锁，与原核对应体没有明显的功能差异。（iii）真核核糖体结合四环素的亲和力比细菌核糖体低15倍（K-d分别为30 μ M和1-2 μ M）。与非酶促tRNA结合a位点相比，该药不影响80S核糖体酶促a位点的占据。这两个观察结果都解释了真核核糖体对这种抗生素的相对抗性。
It is generally believed that basic features of ribosomal functions are universally valid, but a systematic test still stands out for higher eukaryotic 80S ribosomes. Here we report: (i) differences in tRNA and mRNA binding capabilities of eukaryotic and bacterial ribosomes and their subunits. Eukaryotic 40S subunits bind mRNA exclusively in the presence of cognate tRNA, whereas bacterial 30S do bind mRNA already in the absence of tRNA. 80S ribosomes bind mRNA efficiently in the absence of tRNA. In contrast, bacterial 70S interact with mRNA more productively in the presence rather than in the absence of tRNA. (ii) States of initiation (P-i), pre-translocation (PRE) and post-translocation (POST) of the ribosome were checked and no significant functional differences to the prokaryotic counterpart were observed including the reciprocal linkage between A and E sites. (iii) Eukaryotic ribosomes bind tetracycline with an affinity 15 times lower than that of bacterial ribosomes (K-d 30 mu M and 1-2 mu M, respectively). The drug does not effect enzymatic A-site occupation of 80S ribosomes in contrast to non-enzymatic tRNA binding to the A-site. Both observations explain the relative resistance of eukaryotic ribosomes to this antibiotic.