Box H/ACA Small Ribonucleoproteins Tamás Kiss, Eléonore Fayet-Lebaron, Beáta E. Jády  Molecular Cell  Volume 37, Issue 5, Pages 597-606 (March 2010) DOI: 10.1016/j.molcel.2010.01.032 Copyright © 2010 Elsevier Inc. Terms and Conditions

Figure 1 Structure and Function of H/ACA RNAs (A) Isomerization of uridine to pseudouridine. After breakage of the N1-C1 bond of uridine, the free uracil is rotated 180° around the N3-C6 axis and reattached to the ribose through a C1-C5 bond. The resulting pseudouridine possesses an additional potential hydrogen bond donor (N1, indicated in yellow). (B) Schematic structure of archaeal and eukaryotic H/ACA RNAs. The conserved H, ACA, CAB, and k-turn motifs are shown. The target recognition sequences in the pseudouridylation loop (Ψ pocket) are in brown. (C) Selection of target uridines by H/ACA pseudouridylation guides RNAs. Molecular Cell 2010 37, 597-606DOI: (10.1016/j.molcel.2010.01.032) Copyright © 2010 Elsevier Inc. Terms and Conditions

Figure 2 Structure and Function of Archaeal H/ACA RNPs (A) Organization of archaeal H/ACA pseudouridylation-guide RNPs. The H/ACA RNP proteins and the RNA structural elements are indicated by color code. (B) Crystal structure of archaeal H/ACA RNP. The front (left) and side (right) views are shown. The star indicates the catalytic center of Cbf5. Reproduced with permission from Li and Ye (2006). (C) Positioning of the recruited substrate RNA in an H/ACA RNP in the absence of Gar1. The substrate RNA bound to the pseudouridylation pocket forms a U-shaped structure that is aligned vertically to the active surface of Cbf5. Reproduced with permission from Duan et al. (2009). (D) Substrate-induced conformational switch of the thump loop of Cbf5. The Gar1-associated open (gray) and the substrate RNA-bound closed (green) conformations of the thumb loop are shown. The residues involved in protein-protein interactions are highlighted. Reproduced with permission from Duan et al. (2009). Molecular Cell 2010 37, 597-606DOI: (10.1016/j.molcel.2010.01.032) Copyright © 2010 Elsevier Inc. Terms and Conditions

Figure 3 Biogenesis of Eukaryotic H/ACA RNPs Is Promoted by Multiple Trans-Acting Factors For simplicity reasons, only one H/ACA hairpin is shown. The known interactions of H/ACA core proteins and H/ACA assembly factors are shown. The precise molecular role of most assembly factors remains to be elucidated. For details, see the text. Molecular Cell 2010 37, 597-606DOI: (10.1016/j.molcel.2010.01.032) Copyright © 2010 Elsevier Inc. Terms and Conditions

Figure 4 The 3′-Hairpin of snR30/U17 snoRNA Forms a Complex Interaction with 18S rRNA Sequences The invariant rRNA (rm1 and rm2) and snoRNA (m1 and m2) sequences are shown in red and brown, respectively. The terminal stem-loop region interacts with putative rRNA processing factor(s) (PRPF). The box H/ACA core proteins are not shown. Molecular Cell 2010 37, 597-606DOI: (10.1016/j.molcel.2010.01.032) Copyright © 2010 Elsevier Inc. Terms and Conditions

Figure 5 Synthesis of Human Telomeric DNA by Telomerase Schematic structure of the human telomerase RNA (hTR) with the functionally important sequence elements is shown. The template sequence of hTR (purple) recognizes the terminal nucleotides of the telomeric G-rich strand and dictates its elongation by the associated telomerase reverse transcriptase (hTERT). The nascent telomeric DNA is in green. The CAB box (blue) and 3′ end-processing signal (orange) of hTR are indicated. Molecular Cell 2010 37, 597-606DOI: (10.1016/j.molcel.2010.01.032) Copyright © 2010 Elsevier Inc. Terms and Conditions