Publication Date:
2016-01-09
Description:
Splicing of precursor messenger RNA is accomplished by a dynamic megacomplex known as the spliceosome. Assembly of a functional spliceosome requires a preassembled U4/U6.U5 tri-snRNP complex, which comprises the U5 small nuclear ribonucleoprotein (snRNP), the U4 and U6 small nuclear RNA (snRNA) duplex, and a number of protein factors. Here we report the three-dimensional structure of a Saccharomyces cerevisiae U4/U6.U5 tri-snRNP at an overall resolution of 3.8 angstroms by single-particle electron cryomicroscopy. The local resolution for the core regions of the tri-snRNP reaches 3.0 to 3.5 angstroms, allowing construction of a refined atomic model. Our structure contains U5 snRNA, the extensively base-paired U4/U6 snRNA, and 30 proteins including Prp8 and Snu114, which amount to 8495 amino acids and 263 nucleotides with a combined molecular mass of ~1 megadalton. The catalytic nucleotide U80 from U6 snRNA exists in an inactive conformation, stabilized by its base-pairing interactions with U4 snRNA and protected by Prp3. Pre-messenger RNA is bound in the tri-snRNP through base-pairing interactions with U6 snRNA and loop I of U5 snRNA. This structure, together with that of the spliceosome, reveals the molecular choreography of the snRNAs in the activation process of the spliceosomal ribozyme.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wan, Ruixue -- Yan, Chuangye -- Bai, Rui -- Wang, Lin -- Huang, Min -- Wong, Catherine C L -- Shi, Yigong -- New York, N.Y. -- Science. 2016 Jan 29;351(6272):466-75. doi: 10.1126/science.aad6466. Epub 2016 Jan 7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China. ; National Center for Protein Science Shanghai, Institute of Biochemistry and Cell Biology, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26743623" target="_blank"〉PubMed〈/a〉
Keywords:
Catalysis
;
Cryoelectron Microscopy
;
Nucleic Acid Conformation
;
Protein Conformation
;
RNA Precursors/chemistry
;
*RNA Splicing
;
RNA, Messenger/chemistry
;
RNA, Small Nuclear/*chemistry/ultrastructure
;
Ribonucleoprotein, U4-U6 Small Nuclear/*chemistry/ultrastructure
;
Ribonucleoprotein, U5 Small Nuclear/*chemistry/ultrastructure
;
Saccharomyces cerevisiae/*metabolism
;
Saccharomyces cerevisiae Proteins/*chemistry/ultrastructure
;
Spliceosomes/*chemistry/ultrastructure
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
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