RRP17P IS A EXONUCLEASE REQUIRED FOR 5' END PROCESSING OF PRE-60S RIBOSOMAL RNA

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 核糖体的加工需要一系列的核内和核外溶解步骤来生产成熟的核糖体，其中大多数已经被描述过。为了确保核糖体的合成，rRNA的3‘端形成使用多个核酸酶并行作用；然而，对于5’端成熟还没有描述类似的并行机制。在这里，我们确定Rrp17p是一个先前未知的核糖体生物发生所必需的5‘-3’外切酶，与Rat1p以类似于3‘端形成的平行处理途径发挥作用。Rrp17P是有效消化5.8S(S)和25S rRNA成熟5‘端的核酸外切酶所必需的，在其N端附近含有一个催化结构域，在高等真核生物中高度保守，是核酸外切酶家族的成员。我们发现Rrp17p结合了60年代末的前核糖体，伴随着它们从核仁到核周，并为60年代末亚单位加工和出口之间的物理和功能联系提供了证据。已经发表了一篇描述这项工作的论文(M.Oeffinger，D.Zenkulusen，A.Ferguson，K.E.wei，A.El Hage，D.Tollervey，B.T.Chait，R.H.Singer，M.P.Rout，Rrp17p是一种真核外切酶，用于60年代前核糖体RNA分子细胞的50端加工，36(2009)768-781)。

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. Ribosomal processing requires a series of endo- and exonucleolytic steps for the production of mature ribosomes, of which most have been described. To ensure ribosome synthesis, 3' end formation of rRNA uses multiple nucleases acting in parallel; however, a similar parallel mechanism had not been described for 5' end maturation. Here, we identify Rrp17p as a previously unidentified 5'-3' exonuclease essential for ribosome biogenesis, functioning with Rat1p in a parallel processing pathway analogous to that of 3' end formation. Rrp17p is required for efficient exonuclease digestion of the mature 5' ends of 5.8S(S) and 25S rRNAs, contains a catalytic domain close to its N terminus, and is highly conserved among higher eukaryotes, being a member of a family of exonucleases. We show that Rrp17p binds late pre-60S ribosomes, accompanying them from the nucleolus to the nuclear periphery, and provide evidence for physical and functional links between late 60S subunit processing and export. A paper describing this work has been published (M. Oeffinger, D. Zenklusen, A. Ferguson, K.E. Wei, A. El Hage, D. Tollervey, B.T. Chait, R.H. Singer, M.P. Rout "Rrp17p Is a Eukaryotic Exonuclease Required for 50 End Processing of Pre-60S Ribosomal RNA" Molecular Cell, 36 (2009) 768-781).