A cytotoxic ribonuclease which specifically cleaves four isoaccepting arginine tRNAs at their anticodon loops
A cytotoxic ribonuclease which specifically cleaves four isoaccepting arginine tRNAs at their anticodon loops
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DOI：
10.1073/pnas.140213797
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发表时间：
2000-07-18
影响因子：
11.1
通讯作者：
Masaki, H
中科院分区：
文献类型：
--
作者：
Tomita, K;Ogawa, T;Masaki, H
通过灭活核糖体感染大肠杆菌细胞，就像大肠杆菌素E3一样。在这里，我们表明，大肠杆菌素D特异性地切割tRNA（精氨酸），包括四个isoconepting分子在体内和体外。在体外，切割发生在反密码子环的38和39位之间，具有2 '.3'-环磷酸末端，并被特异性免疫蛋白抑制。与tRNA（Arg）的切割一致，大肠杆菌素处理的细胞的RNA部分仅对精氨酸显著降低了氨基酸接受活性。此外。我们在C-末端可能的催化结构域中产生了组氨酸的单一突变，其导致体内杀伤活性以及体内和体外tRNA（Arg）切割活性的丧失。这些发现表明，大肠杆菌素D直接切割细胞质tRNA（Arg），导致蛋白质合成受损和细胞死亡。最近我们发现大肠杆菌素E5通过切割Tyr的特异性tRNA的反密码子来停止蛋白质合成。他的，Asn。和Asp.尽管对tRNA和细胞的作用明显相似，但大肠杆菌素D和E5不仅没有序列同源性，而且在底物识别和催化反应方面具有不同的分子机制。
infected Escherichia coli cells by inactivating ribosomes, just like colicin E3. Here, we show that colicin D specifically cleaves tRNAs(Arg) including four isoaccepting molecules both in vivo and in vitro. The cleavage occurs in vitro between positions 38 and 39 in an anticodon loop with a 2'.3'-cyclic phosphate end, and is inhibited by a specific immunity protein. Consistent with the cleavage of tRNAs(Arg) the RNA fraction of colicin-treated cells significantly reduced the amino acid-accepting activity only for arginine. Furthermore. we generated a single mutation of histidine in the C-terminal possible catalytic domain, which caused the loss of the killing activity in vivo together with the tRNA(Arg)-cleaving activity both in vivo and in vitro. These findings show that colicin D directly cleaves cytoplasmic tRNAs(Arg), which leads to impairment of protein synthesis and cell death. Recently. we found that colicin E5 stops protein synthesis by cleaving the anticodons of specific tRNAs for Tyr. His, Asn. and Asp. Despite these apparently similar actions on tRNAs and cells, colicins D and E5 not only exhibit no sequence homology but also have different molecular mechanisms as to both substrate recognition and catalytic reaction.