Nuclear recycling of the pre-60S ribosomal subunit-associated factor Arx1 depends on Rei1 in Saccharomyces cerevisiae
Nuclear recycling of the pre-60S ribosomal subunit-associated factor Arx1 depends on Rei1 in Saccharomyces cerevisiae
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DOI：
10.1128/mcb.26.10.3718-3727.2006
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发表时间：
2006-05-01
影响因子：
5.3
通讯作者：
Johnson, Arlen W.
中科院分区：
文献类型：
--
作者：
Hung, Nai-Jung;Johnson, Arlen W.
Arx 1和雷尔存在于晚期前60 S核糖体颗粒上，含有输出接头Nmd 3-Arx 1与甲硫氨酸氨基肽酶（MetAP）相关，而雷尔是一种C2 H2锌指蛋白，其在核糖体生物发生中的功能以前尚未被表征。Arx 1和Rei 1。主要定位于细胞核和细胞质，分别，但可以共免疫沉淀，表明它们是短暂的在同一个60 S复合物。arx 1 Delta突变体在细胞核中显示出60 S亚基的适度积累，表明Arx 1增强60 S输出。REI 1的缺失导致冷敏感性和Arx 1重新分布到细胞质中，在那里它仍然与游离的60 S亚基结合。然而，ARX 1的缺失或增强的GFP（eGFP）与Rpl 25的融合抑制了reA突变体的冷敏感性。Rp 125或其邻近蛋白Rp 135上的eGFP的存在减少了Arx 1与60 S亚基的结合，表明Arx 1在出口通道附近与60 S亚基结合。Arx 1的突变破坏了其与60 S的结合，也抑制了rei 1 Delta突变体，并恢复了Arx 1的正常核定位。这些结果表明，rei 1 Delta细胞的冷敏感性是由于Arx 1在细胞质中的60 S亚基上的持续存在。此外，这些结果表明，雷尔是需要从新生的60 S亚基Arx 1输出到细胞质后释放，但不为随后的Arx 1的核输入。
Arx1 and Reil are found on late pre-60S ribosomal particles containing the export adaptor Nmd3- Arx1 is related to methionine aminopeptidases (MetAPs), and Reil is a C2H2 zinc finger protein whose function in ribosome biogenesis has not been previously characterized. Arx1 and Rei1. localized predominately to the nucleus and cytoplasm, respectively, but could be coimmunoprecipitated, suggesting that they are transiently in the same 60S complex. arx1 Delta mutants showed a modest accumulation of 60S subunits in the nucleus, suggesting that Arx1 enhances 60S export. Deletion of REI1 led to cold sensitivity and redistribution of Arx1 to the cytoplasm, where it remained bound to free 60S subunits. However, deletion of ARX1 or the fusion of enhanced GFP (eGFP) to Rp125 suppressed the cold sensitivity of an rei]A mutant. The presence of eGFP on Rp125 or its neighboring protein Rp135 reduced the binding of Arx1 to 60S subunits, suggesting that Arx1 binds to 60S subunits in the vicinity of the exit tunnel. Mutations in Arx1 that disrupted its binding to 60S also suppressed an rei1 Delta mutant and restored the normal nuclear localization of Arx1. These results indicate that the cold sensitivity of rei1 Delta cells is due to the persistence of Arx1 on 60S subunits in the cytoplasm. Furthermore, these results suggest that Reil is needed for release of Arx1 from nascent 60S subunits after export to the cytoplasm but not for the subsequent nuclear import of Arx1.