Modomics - A Database of RNA Modifications

ID Card:

Full name: H/ACA ribonucleoprotein complex subunit 2
Synonym: 15.5kD
GI: 59799862
Orf: YDL208W
COG: COG1358
UniProt: P32495
Structures: | 2LBW | 2LBX |
Complex: H/ACA RNP

PDB Structures:


Structure Description:


Abstract of the PDB Structure's related Publication:

H/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 α-β-α 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.

Download RCSB-PDB Structures:

Pdb Files   2LBW.pdb   2LBX.pdb  
Pdbx/mmCIF Files   2LBW.cif   2LBX.cif  

Protein sequence:



Nhp2 (15.5kD) protein is a homologue of yeast Snu13 and Archaea L7Ae. Binds to a common kink-turn motif of snoRNA. One of the essential subunits of H/ACA RNP complex catalysing pseudouridine formation in various RNAs and also mediating telomerase maintenance. Is is also a part of the eukaryotic pre-mRNA splicesomal RNP apparatus complex.


Title Authors Journal Details PubMed Id DOI
Sequence and genetic analysis of NHP2: a moderately abundant high mobility group-like nuclear protein with an essential function in Saccharomyces cerevisiae. Kolodrubetz D, Burgum A Yeast [details] 2063628 -
Reconstitution and structural analysis of the yeast box H/ACA RNA-guided pseudouridine synthase. Li S, Duan J, Li D, Yang B, Dong M, Ye K Genes Dev [details] 22085967 -
Cbf5p, the putative pseudouridine synthase of H/ACA-type snoRNPs, can form a complex with Gar1p and Nop10p in absence of Nhp2p and box H/ACA snoRNAs. Henras AK, Capeyrou R, Henry Y, Caizergues-Ferrer M RNA [details] 15388873 -
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 [details] 21708174 -


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