Cytoplasmic recycling of 60S preribosomal factors depends on the AAA protein drg1
Cytoplasmic recycling of 60S preribosomal factors depends on the AAA protein drg1
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DOI：
10.1128/mcb.00668-07
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发表时间：
2007-10-01
影响因子：
5.3
通讯作者：
Bergler, Helmut
中科院分区：
文献类型：
--
作者：
Pertschy, Brigitte;Saveanu, Cosmin;Bergler, Helmut
DRG1/AFG2 的等位基因形式赋予对药物重氮硼啉（一种酿酒酵母核糖体生物合成抑制剂）的抗性。我们的结果表明 AAA-ATPase Drg1 对于 60S 成熟至关重要，并与细胞质中的 60S 前体颗粒相关。 Drg1 的功能失活导致穿梭 60S 前成熟因子（如 Rlp24、Arx1 和 Tif6）的细胞质定位增加。令人惊讶的是，Nog1（一种核前 60S 因子）在这些条件下也重新定位到细胞质，这表明它是一种以前未曾怀疑的穿梭前核糖体因子，与前体颗粒一起输出并非常快速地重新输入。在 drg1 突变条件下变成细胞质的蛋白质在 Reil（一种后期作用的前核糖体因子）结合之前的一个步骤中被阻断在 pre-60S 颗粒上。在 D2 ATPase 结构域中突变的显性失活 Drg1 变体过度表达后，可以看到类似的前 60S 结合形式的 Nog1 和 Rlp24 在细胞质中的积累。我们得出的结论是，Drg1 的 ATP 酶活性是 60S 前颗粒核输出后不久释放穿梭蛋白所必需的。这种早期细胞质释放反应定义了真核核糖体成熟的新步骤。
Allelic forms of DRG1/AFG2 confer resistance to the drug diazaborine, an inhibitor of ribosome biogenesis in Saccharomyces cerevisiae. Our results show that the AAA-ATPase Drg1 is essential for 60S maturation and associates with 60S precursor particles in the cytoplasm. Functional inactivation of Drg1 leads to an increased cytoplasmic localization of shuttling pre-60S maturation factors like Rlp24, Arx1, and Tif6. Surprisingly, Nog1, a nuclear pre-60S factor, was also relocalized to the cytoplasm under these conditions, suggesting that it is a previously unsuspected shuttling preribosomal factor that is exported with the precursor particles and very rapidly reimported. Proteins that became cytoplasmic under drg1 mutant conditions were blocked on pre-60S particles at a step that precedes the association of Reil, a later-acting preribosomal factor. A similar cytoplasmic accumulation of Nog1 and Rlp24 in pre-60S-bound form could be seen after overexpression of a dominant-negative Drg1 variant mutated in the D2 ATPase domain. We conclude that the ATPase activity of Drg1 is required for the release of shuttling proteins from the pre-60S particles shortly after their nuclear export. This early cytoplasmic release reaction defines a novel step in eukaryotic ribosome maturation.