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Xenopus LSm proteins bind U8 snoRNA via an internal evolutionarily conserved octamer sequence
Nenad Tomasevic1, Brenda A Peculis
1Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-1766, USA.
Molecular and Cellular Biology
|May 25, 2002
Summary
Researchers identified a specific protein complex that binds U8 small nucleolar RNA (snoRNA), crucial for ribosome biogenesis. This LSm complex specifically recognizes U8 RNA, revealing new insights into its essential role.
Area of Science:
- Molecular Biology
- RNA Biology
- Biochemistry
Background:
- U8 small nucleolar RNA (snoRNA) is essential for the maturation of 5.8S and 28S ribosomal RNAs, which form the large ribosomal subunit.
- The precise in vivo mechanisms governing U8 snoRNA's function remain incompletely understood.
Purpose of the Study:
- To identify and characterize proteins that form a specific complex with U8 snoRNA.
- To elucidate the molecular interactions underlying U8 snoRNA's role in ribosome biogenesis.
Main Methods:
- Purification and biochemical characterization of an U8 RNA-binding protein complex.
- Protein identification using Xenopus homologues of LSm proteins.
- In vitro binding assays with U6, U3, and U14 snoRNAs.
- In vivo association studies of the complex with U8 RNA.
Main Results:
- A stable 75-kDa U8 RNA-binding complex was purified, requiring a conserved octamer sequence in U8 RNA for high-affinity binding.
- The complex contains Xenopus LSm2, -3, -4, -6, -7, and -8 proteins and associates with U8 RNA in vivo.
- The purified complex specifically binds U8 and U6 snoRNAs in vitro, but not U3 or U14 snoRNAs.
Conclusions:
- The LSm complex specifically recognizes and binds U8 snoRNA, suggesting a key role in U8 RNA metabolism and function.
- This finding provides mechanistic insights into the essential role of U8 snoRNA in large ribosomal subunit biogenesis.