Atomic modeling of the ITS2 ribosome assembly subcomplex from cryo-EM together with mass spectrometry-identified protein-protein crosslinks

作者：Wu, Shan; Tan, Dan; Woolford, John L., Jr.; Dong, Meng-Qiu; Gao, Ning^*

来源：Protein Science, 2017, 26(1): 103-112.

DOI：10.1002/pro.3045

• cryo-EM
• CXMS
• ITS2
• ribosome assembly
• Cic1
• Nop7
• RIp7
• Nop15
• Nop53
• crosslinking

The assembly of ribosomal subunits starts in the nucleus, initiated by co-transcriptional folding of nascent ribosomal RNA (rRNA) transcripts and binding of ribosomal proteins and assembly factors. The internal transcribed spacer 2 (ITS2) is a precursor sequence to be processed from the intermediate 27S rRNA in the nucleoplasm; its removal is required for nuclear export of pre-60S particles. The proper processing of the ITS2 depends on multiple associated assembly factors and RNases. However, none of the structures of the known ITS2-binding factors is available. Here, we describe the modeling of the ITS2 subcomplex, including five assembly factors Cic1, Nop7, Nop15, Nop53, and RIp7, using a combination of cryo-electron microscopy and cross-linking of proteins coupled with mass spectrometry approaches. The resulting atomic models provide structural insights into their function in ribosome assembly, and establish a framework for further dissection of their molecular roles in ITS2 processing.

• 出版日期2017-1
• 单位清华大学; 北京生命科学研究所