2nnw | pdb_00002nnw
Alternative conformations of Nop56/58-fibrillarin complex and implication for induced-fit assenly of box C/D RNPs
Structural highlights
Function[FLPA_PYRFU] Involved in pre-rRNA and tRNA processing. Utilizes the methyl donor S-adenosyl-L-methionine to catalyze the site-specific 2'-hydroxyl methylation of ribose moieties in rRNA and tRNA. Site specificity is provided by a guide RNA that base pairs with the substrate. Methylation occurs at a characteristic distance from the sequence involved in base pairing with the guide RNA (By similarity).[HAMAP-Rule:MF_00351] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe Nop56/58-fibrillarin heterocomplex is a core protein complex of the box C/D ribonucleoprotein particles that modify and process ribosomal RNAs. The previous crystal structure of the Archaeoglobus fulgidus complex revealed a symmetric dimer of two Nop56/58-fibrillarin complexes linked by the coiled-coil domains of the Nop56/68 proteins. However, because the A. fulgidus Nop56/58 protein lacks some domains found in most other species, it was thought that the bipartite architecture of the heterocomplex was not likely a general phenomenon. Here we report the crystal structure of the Nop56/58-fibrillarin complex bound with methylation cofactor, S-adenosyl-L-methionine from Pyrococcus furiosus, at 2.7 A. The new complex confirms the generality of the previously observed bipartite arrangement. In addition however, the conformation of Nop56/58 in the new structure differs substantially from that in the earlier structure. The distinct conformations of Nop56/58 suggest potential flexibility in Nop56/58. Computational normal mode analysis supports this view. Importantly, fibrillarin is repositioned within the two complexes. We propose that hinge motion within Nop56/58 has important implications for the possibility of simultaneously positioning two catalytic sites at the two target sites of a bipartite box C/D guide RNA. Alternative conformations of the archaeal Nop56/58-fibrillarin complex imply flexibility in box C/D RNPs.,Oruganti S, Zhang Y, Li H, Robinson H, Terns MP, Terns RM, Yang W, Li H J Mol Biol. 2007 Aug 31;371(5):1141-50. Epub 2007 Jun 15. PMID:17617422[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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