한빛사 논문
Abstract
Jeongsik Yong,1,2 Mumtaz Kasim,1,2 Jennifer L. Bachorik,1 Lili Wan,1 and Gideon Dreyfuss1,*
1Howard Hughes Medical Institute and Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6148, USA
2These authors contributed equally to this work
*Correspondence
DOI 10.1016/j.molcel.2010.03.014
SUMMARY
The SMN complex assembles Sm cores on snRNAs, a key step in the biogenesis of snRNPs, the spliceosome’s major components. Here, using SMN complex inhibitors identified by high-throughput screening and a ribo-proteomic strategy on formaldehyde crosslinked RNPs, we dissected this pathway in cells.Weshow that protein synthesis inhibition impairs the SMN complex, revealing discrete SMN and Gemin subunits and accumulating an snRNA precursor (pre-snRNA)-Gemin5 intermediate. By high-throughput sequencing of this transient intermediate’s RNAs, we discovered the previously undetectable precursors of all the snRNAs and identified their Gemin5-binding sites. We demonstrate that pre-snRNA 30 sequences function to enhance snRNP biogenesis. The SMN complex is also inhibited by oxidation, and we show that it stalls an inventory-complete SMN complex containing presnRNAs. We propose a stepwise pathway of SMN complex formation and snRNP biogenesis, highlighting Gemin5’s function in delivering pre-snRNAs as substrates for Sm core assembly and processing.
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