An intact Box C sequence in the U3 snRNA is required for binding of fibrillarin, the protein common to the major family of nucleolar snRNPs. EMBO J

Department of Molecular Biophysics and Biochemistry, Howard Hughes Medical Institute, Yale School of Medicine, New Haven, CT 06511.
The EMBO Journal (Impact Factor: 10.43). 10/1991; 10(9):2645-51.
Source: PubMed


The mammalian U3 snRNP is one member of a recently described family of nucleolar snRNPs which also includes U8, U13, U14, X and Y. All of these snRNPs are immunoprecipitable by anti-fibrillarin autoantibodies, suggesting the existence of a common binding site for the 34 kDa fibrillarin (Fb) protein. Two short nucleotide sequences, called Boxes C and D, present in each of these RNAs are the most likely sites for fibrillarin binding. We have developed a HeLa in vitro assembly system for binding of fibrillarin to human U3 snRNA. Reconstitution of the input RNA is specific in our assay since four of the other nucleolar small RNAs (U8, U13, X and Y) which have Boxes C and D become immunoprecipitable by anti-fibrillarin whereas two RNAs which lack these sequences (5S and 5.8S) do not. Deletion analyses of the U3 snRNA demonstrate that the presence of Box C but not Box D is required for fibrillarin binding. Moreover, seven single or double site-specific mutations in the U3 Box C abolish binding. The role of the Box C-fibrillarin interaction in the biogenesis of the Fb snRNPs is discussed.

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    • "If true for sporadic cases, Snord3A levels may be used to identify at risk individuals of all etiologies, and in the future, as a marker of treatment success. Snord3A, or in its other denomination U3 small nucleolar RNA, was shown to be part of the complex comprising fibrillarin and the survival motor neuron gene (SMN1) [41], [42], implicated in ALS pathogenesis via oxidative pathways [36]. On another note, other SnoRnas were recently recognized as mediators of oxidative and ER stress [25]. "
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    • "In 1985, anti-U3-RNP antibodies were isolated by IP techniques [94]. More recently it was shown that the mammalian U3 small nuclear RNP (snRNP) is one member of a family of nucleolar snRNPs that are immunoprecipitable by anti-fibrillarin autoantibodies [95]. AFA are present in about 4% of patients with SSc and are mutually exclusive with ACA, anti-Scl-70, and anti-RNAP [96]. "
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    • "Fibrillarin is highly conserved in sequence, structure, and function in eukaryotes (Schimmang et al. 1989; Henriquez et al. 1990; Lapeyre et al. 1990; Aris and Blobel 1991; Jansen et al. 1991; Girard et al. 1993; Turley et al. 1993; Cappai et al. 1994; David et al. 1997). Fibrillarin, named Nop1p in yeast, is an essential component of box C/D snoRNPs (Tyc and Steitz 1989; Aris and Blobel 1991; Baserga et al. 1991) that function in site-specific 2′-O-methylation of pre-rRNA (Kiss-Laszlo et al. 1996; Tycowski et al. 1996; Dunbar and Baserga 1998). Fibrillarin is directly involved in many posttranscriptional processes including pre-rRNA processing, pre-rRNA methylation, and ribosome assembly (Tollervey et al. 1993). "
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