3u28
Crystal structure of a Cbf5-Nop10-Gar1 complex from Saccharomyces cerevisiae
Structural highlights
FunctionCBF5_YEAST Plays a central role in ribosomal RNA processing. Probable catalytic subunit of H/ACA small nucleolar ribonucleoprotein (H/ACA snoRNP) 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. May function as a pseudouridine synthase. Binds in vitro to centromeres and microtubules. It is a centromeric DNA-CBF3-binding factor which is involved in mitotic chromosome segregation. Essential for cell growth.[1] [2] [3] [4] [5] Publication Abstract from PubMedBox H/ACA ribonucleoprotein particles (RNPs) mediate pseudouridine synthesis, ribosome formation, and telomere maintenance. The structure of eukaryotic H/ACA RNPs remains poorly understood. We reconstituted functional Saccharomyces cerevisiae H/ACA RNPs with recombinant proteins Cbf5, Nop10, Gar1, and Nhp2 and a two-hairpin H/ACA RNA; determined the crystal structure of a Cbf5, Nop10, and Gar1 ternary complex at 1.9 A resolution; and analyzed the structure-function relationship of the yeast complex. Although eukaryotic H/ACA RNAs have a conserved two-hairpin structure, isolated single-hairpin RNAs are also active in guiding pseudouridylation. Nhp2, unlike its archaeal counterpart, is largely dispensable for the activity, reflecting a functional adaptation of eukaryotic H/ACA RNPs to the variable RNA structure that Nhp2 binds. The N-terminal extension of Cbf5, a hot spot for dyskeratosis congenita mutation, forms an extra structural layer on the PUA domain. Gar1 is distinguished from the assembly factor Naf1 by containing a C-terminal extension that controls substrate turnover and the Gar1-Naf1 exchange during H/ACA RNP maturation. Our results reveal significant novel features of eukaryotic H/ACA RNPs. 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. 2011 Nov 15;25(22):2409-21. PMID:22085967[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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