INTERDEPENDENCE OF YEAST RIBOSOME ASSEMBLY FACTORS

这个子项目是许多利用 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 Ytm 1、Nop 7和Erb 1是60 S核糖体亚基组装所必需的重要的、保守的核仁蛋白。 这三种蛋白质中的每一种都依赖于另一种蛋白质组装成前核糖体并与前核糖体稳定结合。在它们不存在的情况下，27 SA 3 pre-rRNA到27 SB pre-rRNA的加工被阻断。Nop 7的中心结构域与Erb 1的保守氨基末端中间之间的相互作用是它们被募集到前rRNP中所必需的。然后Ytm 1的WD 40基序与Erb 1的Nop 7结合位点的氨基末端结合。 与这些相互作用的结构域相一致，仅含有这些相互作用结构域的截短的Ytm 1或Erb 1构建体的表达使蛋白质能够彼此缔合，组装成前核糖体，并对核糖体生物合成产生显性负效应。Ytm 1保守的氨基端的一半或Erb 1保守的C端的WD 40基序的功能是什么，它们在这些显性负截短中缺失？ Erb 1也可能在细胞生长和增殖中起作用; Erb 1的过表达干扰有丝分裂染色体分离。Erb 1是如何参与这一过程的？ 为了解决这些问题，我们正在使用Ytm 1的氨基末端一半，Erb 1的C末端一半和全长Erb 1进行全基因组双杂交筛选。Erb 1和Ytm 1的这些部分与其他分子在组装核糖体的相互作用可能是至关重要的，以建立适当的动力学的核糖体生物合成。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Ytm1, Nop7, and Erb1 are essential, conserved nucleolar proteins necessary for assembly of 60S ribosomal subunits. Each of these three proteins is dependent on the other for their assembly into and stable association with preribosomes. In their absence, processing of 27SA3 pre-rRNA to 27SB pre-rRNA is blocked. Interaction between the central domain of Nop7 with the conserved amino-terminal middle of Erb1 is required for their recruitment into pre-rRNPs. The WD40 motif of Ytm1 then binds to Erb1 amino-terminal to the Nop7 binding site. Consistent with these domains of interaction, expression of truncated Ytm1 or Erb1 constructs containing only these interaction domains enables the proteins to associate with each other, assemble into preribosomes, and cause a dominant negative effect on ribosome biogenesis. What are the functions of the conserved amino-terminal half of Ytm1 or the conserved WD40 motif in the C-terminal half of Erb1, which are missing in these dominant-negative truncations? Erb1 also may function in cell growth and proliferation; overexpression of Erb1 interferes with mitotic chromosome segregation. How does Erb1 participate in this pathway? To address these questions, we are carrying out genome-wide two-hybrid screens using the amino-terminal half of Ytm1, the C-terminal half of Erb1 and full-length Erb1. Interactions of these portions of Erb1 and Ytm1 with other molecules in assembling ribosomes may be critical to establish proper dynamics of ribosome biogenesis.