CONSERVED MECHANISM OF TRANSFER-RNA SPLICING IN EUKARYOTES
CONSERVED MECHANISM OF TRANSFER-RNA SPLICING IN EUKARYOTES
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DOI：
10.1128/mcb.11.11.5410
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发表时间：
1991-11-01
影响因子：
5.3
通讯作者：
PHIZICKY, EM
中科院分区：
文献类型：
--
作者：
ZILLMANN, M;GOROVSKY, MA;PHIZICKY, EM
酵母和脊椎动物细胞中tRNA剪接的连接步骤被认为是通过根本不同的机制进行的。酵母细胞的连接是通过将来自ATP的外源磷酸掺入到剪接连接中而发生的，伴随着在5‘连接核苷酸处形成2’磷酸。这种磷酸盐在随后的步骤中被去除，在体外，该步骤由依赖于NAD的去磷酸化活性催化。相比之下，脊椎动物中的tRNA连接被报道在没有掺入外源磷酸或形成2‘磷酸的情况下发生。我们在这项研究中证明了在HeLa细胞中存在酵母tRNA连接酶样活性。此外，在这些细胞的提取物中，整个酵母样的tRNA剪接机制是完整的，包括切割、连接和以NAD依赖的方式去除2‘磷酸以获得成熟的tRNA。这些结果表明，tRNA剪接的机制在真核生物中是保守的。
The ligation steps of tRNA splicing in yeast and vertebrate cells have been thought to proceed by fundamentally different mechanisms. Ligation in yeast cells occurs by incorporation of an exogenous phosphate from ATP into the splice junction, with concomitant formation of a 2' phosphate at the 5' junction nucleotide. This phosphate is removed in a subsequent step which, in vitro, is catalyzed by an NAD-dependent dephosphorylating activity. In contrast, tRNA ligation in vertebrates has been reported to occur without incorporation of exogenous phosphate or formation of a 2' phosphate. We demonstrate in this study the existence of a yeast tRNA ligase-like activity in HeLa cells. Furthermore, in extracts from these cells, the entire yeastlike tRNA splicing machinery is intact, including that for cleavage, ligation, and removal of the 2' phosphate in an NAD-dependent fashion to give mature tRNA. These results argue that the mechanism of tRNA splicing is conserved among eukaryotes.