Pérez-Fernández Jorge, Román Angel, De Las Rivas Javier, Bustelo Xosé R, Dosil Mercedes
Centro de Investigación del Cáncer and Instituto de Biología Molecular y Celular del Cáncer, CSIC-University of Salamanca, Campus Unamuno, E-37007 Salamanca, Spain.
Mol Cell Biol. 2007 Aug;27(15):5414-29. doi: 10.1128/MCB.00380-07. Epub 2007 May 21.
The 90S preribosomal particle is required for the production of the 18S rRNA from a pre-rRNA precursor. Despite the identification of the protein components of this particle, its mechanism of assembly and structural design remain unknown. In this work, we have combined biochemical studies, proteomic techniques, and bioinformatic analyses to shed light into the rules of assembly of the yeast 90S preribosome. Our results indicate that several protein subcomplexes work as discrete assembly subunits that bind in defined steps to the 35S pre-rRNA. The assembly of the t-UTP subunit is an essential step for the engagement of at least five additional subunits in two separate, and mutually independent, assembling routes. One of these routes leads to the formation of an assembly intermediate composed of the U3 snoRNP, the Pwp2p/UTP-B, subunit and the Mpp10p complex. The other assembly route involves the stepwise binding of Rrp5p and the UTP-C subunit. We also report the use of a bioinformatic approach that provides a model for the topological arrangement of protein components within the fully assembled particle. Together, our data identify the mechanism of assembly of the 90S preribosome and offer novel information about its internal architecture.
90S前核糖体颗粒是从rRNA前体产生18S rRNA所必需的。尽管已经鉴定出该颗粒的蛋白质成分，但其组装机制和结构设计仍然未知。在这项工作中，我们结合了生化研究、蛋白质组学技术和生物信息学分析，以阐明酵母90S前核糖体的组装规则。我们的结果表明，几个蛋白质亚复合物作为离散的组装亚基，以确定的步骤与35S前rRNA结合。t-UTP亚基的组装是至少五个额外亚基在两条独立且相互独立的组装途径中参与组装的关键步骤。其中一条途径导致形成由U3 snoRNP、Pwp2p/UTP-B亚基和Mpp10p复合物组成的组装中间体。另一条组装途径涉及Rrp5p和UTP-C亚基的逐步结合。我们还报告了一种生物信息学方法的应用，该方法为完全组装颗粒内蛋白质成分的拓扑排列提供了一个模型。总之，我们的数据确定了90S前核糖体的组装机制，并提供了有关其内部结构的新信息。
