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Nat Struct Biol. 2003 Apr;10(4):256-63.

Structure and function of archaeal box C/D sRNP core proteins.

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Department of Chemistry and Biochemistry, Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida 32306, USA.


Nop56p and Nop58p are two core proteins of the box C/D snoRNPs that interact concurrently with fibrillarin and snoRNAs to function in enzyme assembly and catalysis. Here we report the 2.9 A resolution co-crystal structure of an archaeal homolog of Nop56p/Nop58p, Nop5p, in complex with fibrillarin from Archaeoglobus fulgidus (AF) and the methyl donor S-adenosyl-L-methionine. The N-terminal domain of Nop5p forms a complementary surface to fibrillarin that serves to anchor the catalytic subunit and to stabilize cofactor binding. A coiled coil in Nop5p mediates dimerization of two fibrillarin-Nop5p heterodimers for optimal interactions with bipartite box C/D RNAs. Structural analysis and complementary biochemical data demonstrate that the conserved C-terminal domain of Nop5p harbors RNA-binding sites. A model of box C/D snoRNP assembly is proposed based on the presented structural and biochemical data.

[Indexed for MEDLINE]

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