Download MendeleyStructurally Conserved Nop56/58 N-terminal Domain Facilitates Archaeal Box C/D Ribonucleoprotein-guided Methyltransferase Activity.
Gagnon, K.T., Biswas, S., Zhang, X., Brown, B.A., Wollenzien, P., Mattos, C., Maxwell, E.S.(2012) J Biol Chem 287: 19418-19428
- PubMed: 22496443
- DOI: https://doi.org/10.1074/jbc.M111.323253
- Primary Citation of Related Structures:
3T7Z - PubMed Abstract:
Box C/D RNA-protein complexes (RNPs) guide the 2'-O-methylation of nucleotides in both archaeal and eukaryotic ribosomal RNAs. The archaeal box C/D and C'/D' RNP subcomplexes are each assembled with three sRNP core proteins. The archaeal Nop56/58 core protein mediates crucial protein-protein interactions required for both sRNP assembly and the methyltransferase reaction by bridging the L7Ae and fibrillarin core proteins. The interaction of Methanocaldococcus jannaschii (Mj) Nop56/58 with the methyltransferase fibrillarin has been investigated using site-directed mutagenesis of specific amino acids in the N-terminal domain of Nop56/58 that interacts with fibrillarin. Extensive mutagenesis revealed an unusually strong Nop56/58-fibrillarin interaction. Only deletion of the NTD itself prevented dimerization with fibrillarin. The extreme stability of the Nop56/58-fibrillarin heterodimer was confirmed in both chemical and thermal denaturation analyses. However, mutations that did not affect Nop56/58 binding to fibrillarin or sRNP assembly nevertheless disrupted sRNP-guided nucleotide modification, revealing a role for Nop56/58 in methyltransferase activity. This conclusion was supported with the cross-linking of Nop56/58 to the target RNA substrate. The Mj Nop56/58 NTD was further characterized by solving its three-dimensional crystal structure to a resolution of 1.7 Å. Despite low primary sequence conservation among the archaeal Nop56/58 homologs, the overall structure of the archaeal NTD domain is very well conserved. In conclusion, the archaeal Nop56/58 NTD exhibits a conserved domain structure whose exceptionally stable interaction with fibrillarin plays a role in both RNP assembly and methyltransferase activity.
Organizational Affiliation:
Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, North Carolina 27695, USA.
