Sekiguchi Takeshi, Hayano Toshiya, Yanagida Mitsuaki, Takahashi Nobuhiro, Nishimoto Takeharu
Department of Molecular Biology, Graduate School of Medical Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
Nucleic Acids Res. 2006;34(16):4593-608. doi: 10.1093/nar/gkl603. Epub 2006 Sep 8.
Previously, we described a novel nucleolar protein, NOP132, which interacts with the small GTP binding protein RRAG A. To elucidate the function of NOP132 in the nucleolus, we identified proteins that interact with NOP132 using mass spectrometric methods. NOP132 associated mainly with proteins involved in ribosome biogenesis and RNA metabolism, including the DEAD-box RNA helicase protein, DDX47, whose yeast homolog is Rrp3, which has roles in pre-rRNA processing. Immunoprecipitation of FLAG-tagged DDX47 co-precipitated rRNA precursors, as well as a number of proteins that are probably involved in ribosome biogenesis, implying that DDX47 plays a role in pre-rRNA processing. Introduction of NOP132 small interfering RNAs induced a ring-like localization of DDX47 in the nucleolus, suggesting that NOP132 is required for the appropriate localization of DDX47 within the nucleolus. We propose that NOP132 functions in the recruitment of pre-rRNA processing proteins, including DDX47, to the region where rRNA is transcribed within the nucleolus.
此前，我们描述了一种新型核仁蛋白NOP132，它与小GTP结合蛋白RRAG A相互作用。为了阐明NOP132在核仁中的功能，我们使用质谱方法鉴定了与NOP132相互作用的蛋白质。NOP132主要与参与核糖体生物合成和RNA代谢的蛋白质相关，包括DEAD-box RNA解旋酶蛋白DDX47，其酵母同源物是Rrp3，在rRNA前体加工中发挥作用。FLAG标签的DDX47免疫沉淀共沉淀了rRNA前体以及一些可能参与核糖体生物合成的蛋白质，这意味着DDX47在rRNA前体加工中发挥作用。引入NOP132小干扰RNA诱导DDX47在核仁中呈环状定位，表明NOP132是DDX47在核仁内正确定位所必需的。我们提出，NOP132在将包括DDX47在内的rRNA前体加工蛋白募集到核仁内rRNA转录区域中发挥作用。
