Department of Agricultural Chemistry, National Taiwan University, Taipei 10617, Taiwan.
Int J Mol Sci. 2019 Nov 26;20(23):5941. doi: 10.3390/ijms20235941.
Ribosomal proteins are highly expressed, and the quality of ribosomal proteins must be rigorously controlled to build up a functional ribosome. Rpl43, ribosomal protein large subunit 43, is located nearby the E-site of ribosomes. In our previous study, we found that Puf6, Loc1, and Rpl43 form a trimeric complex in . Rpl43 protein levels are under-accumulated in the absence of or . However, why the loss of Puf6 or Loc1 decreased the protein levels of Rpl43 remained unclear. In the present study, we further dissected the connections among these three proteins and found that the processing defects of pre-ribosomal RNA in Δ and Δ are similar to those of the mutant with depletion of Rpl43. The stability of newly synthesized Rpl43 protein decreased slightly in Δ and significantly in Δ. We also found that Puf6 and Loc1 could interact with nascent Rpl43 co-translationally via the N-terminus of Rpl43. While the association and dissociation of Rpl43 with karyopherins did not depend on Puf6 and Loc1, Puf6 and Loc1 interacted with nascent Rpl43 in collaboration. While the N-terminus of Puf6 contained nuclear localization signals for transport, the PUF (Pumilio) domain was essential to interaction with Loc1, Rpl43, and 60S subunits. The C-terminus of Loc1 is more important for interaction with Puf6 and Rpl43. In this study, we found that Puf6 and Loc1 are the dedicated chaperones of ribosomal protein Rpl43 and also analyzed the potential interaction domains among the three proteins. Correct formation of the Puf6, Loc1, and Rpl43 ternary complex is required to properly proceed to the next step in 60S biogenesis.
核糖体蛋白表达水平很高，核糖体蛋白的质量必须严格控制，以构建具有功能的核糖体。核糖体蛋白 L43 （Rpl43）位于核糖体的 E 位附近。在我们之前的研究中，我们发现 Puf6、Loc1 和 Rpl43 形成一个三聚体复合物。在没有 或 时，Rpl43 蛋白水平积累不足。然而，为什么 Puf6 或 Loc1 的缺失会降低 Rpl43 的蛋白水平仍不清楚。在本研究中，我们进一步剖析了这三种蛋白之间的联系，发现 pre-rRNA 在Δ 和 Δ 中的加工缺陷与 Rpl43 耗竭突变体的缺陷相似。新合成的 Rpl43 蛋白在Δ 和Δ 中的稳定性略有下降，而在Δ 中显著下降。我们还发现 Puf6 和 Loc1 可以通过 Rpl43 的 N 端与新生 Rpl43 共翻译相互作用。虽然 Rpl43 与核孔蛋白的结合和解离不依赖于 Puf6 和 Loc1，但 Puf6 和 Loc1 以协作方式与新生 Rpl43 相互作用。虽然 Puf6 的 N 端包含核定位信号以进行运输，但 PUF（Pumilio）结构域对于与 Loc1、Rpl43 和 60S 亚基的相互作用是必不可少的。Loc1 的 C 端对于与 Puf6 和 Rpl43 的相互作用更为重要。在这项研究中，我们发现 Puf6 和 Loc1 是核糖体蛋白 Rpl43 的专用伴侣，并分析了这三种蛋白质之间的潜在相互作用域。正确形成 Puf6、Loc1 和 Rpl43 三元复合物是 60S 生物发生的下一步顺利进行所必需的。
