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Structure and function of archaeal box C/D sRNP core proteins.
Mohamed Aittaleb1, Rumana Rashid, Qiong Chen
1Department of Chemistry and Biochemistry, Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida 32306, USA.
Nature Structural Biology
|February 25, 2003
Summary
Nop5p and fibrillarin form a complex crucial for box C/D small nucleolar ribonucleoprotein (snoRNP) assembly. This structure reveals how Nop5p anchors fibrillarin and binds RNA, aiding enzyme function.
Area of Science:
- Biochemistry
- Structural Biology
- Molecular Biology
Background:
- Box C/D small nucleolar ribonucleoproteins (snoRNPs) are essential for rRNA modification.
- Nop56p and Nop58p are core proteins involved in snoRNP assembly and catalysis.
- Fibrillarin is a key component interacting with Nop56p/Nop58p and snoRNAs.
Purpose of the Study:
- To elucidate the structural basis of box C/D snoRNP assembly.
- To understand the interaction between Nop5p, fibrillarin, and S-adenosyl-L-methionine.
- To reveal the mechanism of RNA binding by Nop5p.
Main Methods:
- Co-crystallization of archaeal Nop5p and fibrillarin from Archaeoglobus fulgidus.
- X-ray crystallography at 2.9 A resolution.
- Biochemical assays to confirm RNA binding.
Main Results:
- The co-crystal structure reveals the N-terminal domain of Nop5p anchors fibrillarin and stabilizes cofactor binding.
- A coiled coil in Nop5p mediates dimerization of fibrillarin-Nop5p heterodimers for RNA interaction.
- The C-terminal domain of Nop5p contains RNA-binding sites.
Conclusions:
- A structural model for box C/D snoRNP assembly is proposed.
- Nop5p plays a critical role in both catalytic subunit anchoring and RNA binding.
- The findings provide insights into the mechanism of snoRNP biogenesis.