Rat1p and Xrn1p are functionally interchangeable exoribonucleases that are restricted to and required in the nucleus and cytoplasm, respectively
Rat1p and Xrn1p are functionally interchangeable exoribonucleases that are restricted to and required in the nucleus and cytoplasm, respectively
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DOI：
10.1128/mcb.17.10.6122
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发表时间：
1997-10-01
影响因子：
5.3
通讯作者：
Johnson, AW
中科院分区：
文献类型：
--
作者：
Johnson, AW
XRN 1编码丰富的胞质核糖核酸外切酶Xrn 1 p，负责酵母中的mRNA周转。筛选旁路抑制剂的活力的xrn 1 SKI 2双突变体确定显性等位基因的RAT 1，编码与Xrn 1 p同源的核糖核酸外切酶。这些RAT 1等位基因恢复了XRN 1样功能，包括细胞质RNA周转，野生型对微管不稳定药物苯菌灵的敏感性和孢子形成。突变定位于编码推定的二分核定位序列（NLS）的RAT 1基因的区域。与绿色荧光蛋白的融合用于证明野生型Rat 1 p定位于核，并且突变等位基因导致Rat 1 p错误定位于细胞质。相反，通过加入猿猴病毒40大T抗原NLS将Xrn 1 p靶向细胞核导致大鼠1 -1株的温度敏感性的互补，这些结果表明，Xrn 1 p和Rat 1 p是功能上可互换的核糖核酸外切酶，分别在细胞质和细胞核中起作用并仅限于细胞质和细胞核。这些蛋白质的高等真核同源物可能在细胞质和细胞核中具有相似的功能。
XRN1 encodes an abundant cytoplasmic exoribonuclease, Xrn1p, responsible for mRNA turnover in yeast. A screen for bypass suppressors of the inviability of xrn1 ski2 double mutants identified dominant alleles of RAT1, encoding an exoribonuclease homologous with Xrn1p. These RAT1 alleles restored XRN1-like functions, including cytoplasmic RNA turnover, wild-type sensitivity to the microtubule-destabilizing drug benomyl, and sporulation. The mutations were localized to a region of the RAT1 gene encoding a putative bipartite nuclear localization sequence (NLS), Fusions to green fluorescent protein were used to demonstrate that wild-type Rat1p is localized to the nucleus and that the mutant alleles result in mislocalization of Rat1p to the cytoplasm, Conversely, targeting Xrn1p to the nucleus by the addition of the simian virus 40 large-T-antigen NLS resulted in complementation of the temperature sensitivity of a rat1-1 strain, These results indicate that Xrn1p and Rat1p are functionally interchangeable exoribonucleases that function in and are restricted to the cytoplasm and nucleus, respectively. It is likely that the higher eukaryotic homologs of these proteins will function similarly in the cytoplasm and nucleus.