3zv0
From Proteopedia
Structure of the SHQ1P-CBF5P complex
Structural highlights
Function[SHQ1_YEAST] Involved in the early biogenesis steps of box H/ACA snoRNP assembly.[1] [CBF5_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.[2] [3] [4] [5] [6] Publication Abstract from PubMedSHQ1 is an essential assembly factor for H/ACA ribonucleoproteins (RNPs) required for ribosome biogenesis, pre-mRNA splicing, and telomere maintenance. SHQ1 binds dyskerin/NAP57, the catalytic subunit of human H/ACA RNPs, and this interaction is modulated by mutations causing X-linked dyskeratosis congenita. We report the crystal structure of the C-terminal domain of yeast SHQ1, Shq1p, and its complex with yeast dyskerin/NAP57, Cbf5p, lacking its catalytic domain. The C-terminal domain of Shq1p interacts with the RNA-binding domain of Cbf5p and, through structural mimicry, uses the RNA-protein-binding sites to achieve a specific protein-protein interface. We propose that Shq1p operates as a Cbf5p chaperone during RNP assembly by acting as an RNA placeholder, thereby preventing Cbf5p from nonspecific RNA binding before association with an H/ACA RNA and the other core RNP proteins. The H/ACA RNP assembly factor SHQ1 functions as an RNA mimic.,Walbott H, Machado-Pinilla R, Liger D, Blaud M, Rety S, Grozdanov PN, Godin K, van Tilbeurgh H, Varani G, Meier UT, Leulliot N Genes Dev. 2011 Nov 15;25(22):2398-408. PMID:22085966[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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