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

这个子项目是许多利用资源的研究子项目之一 由NIH/NCRR资助的中心拨款提供。子项目的主要支持 而子项目的主要调查员可能是由其他来源提供的， 包括其它NIH来源。 列出的子项目总成本可能 代表子项目使用的中心基础设施的估计数量， 而不是由NCRR赠款提供给子项目或子项目工作人员的直接资金。 核糖体加工需要一系列的内切和外切核酸裂解步骤来产生成熟的核糖体，其中大部分已经描述。为了确保核糖体合成，rRNA的3'端形成使用多个平行作用的核酸酶;然而，类似的平行机制尚未被描述用于5'端成熟。在这里，我们确定Rrp 17 p作为一个以前未确定的5 '-3'核酸外切酶的核糖体生物合成所必需的，功能与Rat 1 p在一个平行的加工途径类似的3'端形成。Rrp 17 p是5.8S（S）和25 S rRNA成熟5'端的有效外切核酸酶消化所必需的，在其N端附近含有催化结构域，并且在高等真核生物中高度保守，是外切核酸酶家族的成员。我们发现，Rrp 17 p结合晚期前60 S核糖体，伴随着他们从核仁到核周边，并提供证据晚60 S亚基加工和出口之间的物理和功能联系。描述这项工作的论文已经发表（M。Oeffinger，D. Zenklusen，A.弗格森，K.E. Wei，A. El Hage，D. Tollervey，B.T. Chait，R.H. Singer，M.P. Rout“Rrpl7p Is a Eukaryotic Exonuclease Required for 50 End Processing of Pre-60S Ribosomal RNA”Molecular Cell，36（2009）768-781）。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. 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).