2lbx
From Proteopedia
Solution structure of the S. cerevisiae H/ACA RNP protein Nhp2p
Structural highlights
FunctionNHP2_YEAST Required for ribosome biogenesis. Part of a complex which catalyzes pseudouridylation of rRNA. This involves the isomerization of uridine such that the ribose is subsequently attached to C5, instead of the normal N1. Pseudouridine ("psi") residues may serve to stabilize the conformation of rRNAs. Essential for growth. Directly binds H/ACA snoRNAs.[1] [2] [3] Publication Abstract from PubMedH/ACA small nucleolar and Cajal body ribonucleoproteins (RNPs) function in site-specific pseudouridylation of eukaryotic rRNA and snRNA, rRNA processing, and vertebrate telomerase biogenesis. Nhp2, one of four essential protein components of eukaryotic H/ACA RNPs, forms a core trimer with the pseudouridylase Cbf5 and Nop10 that binds to H/ACA RNAs specifically. Crystal structures of archaeal H/ACA RNPs have revealed how the protein components interact with each other and with the H/ACA RNA. However, in place of Nhp2p, archaeal H/ACA RNPs contain L7Ae, which binds specifically to an RNA K-loop motif absent from eukaryotic H/ACA RNPs, while Nhp2 binds a broader range of RNA structures. We report solution NMR studies of Saccharomyces cerevisiae Nhp2 (Nhp2p), which reveal that Nhp2p exhibits two major conformations in solution due to cis/trans isomerization of the evolutionarily conserved Pro83. The equivalent proline is in the cis conformation in all reported structures of L7Ae and other homologous proteins. Nhp2p has the expected alpha-beta-alpha fold, but the solution structures of the major conformation of Nhp2p with trans Pro83 and of Nhp2p-S82W with cis Pro83 reveal that Pro83 cis/trans isomerization affects the positions of numerous residues at the Nop10 and RNA binding interface. An S82W substitution, which stabilizes the cis conformation, also stabilizes the association of Nhp2p with H/ACA snoRNPs expressed in vivo. We propose that Pro83 plays a key role in the assembly of the eukaryotic H/ACA RNP, with the cis conformation locking in a stable Cbf5-Nop10-Nhp2 ternary complex and positioning the protein backbone to interact with the H/ACA RNA. Structure of H/ACA RNP Protein Nhp2p Reveals Cis/Trans Isomerization of a Conserved Proline at the RNA and Nop10 Binding Interface.,Koo BK, Park CJ, Fernandez CF, Chim N, Ding Y, Chanfreau G, Feigon J J Mol Biol. 2011 Sep 2;411(5):927-42. Epub 2011 Jun 25. PMID:21708174[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
| ||||||||||||||||||
Categories: Large Structures | Saccharomyces cerevisiae | Chanfreau G | Chim N | Ding Y | Feigon J | Fernandez CF | Koo B | Park C
