Cbf5p, a potential pseudouridine synthase, and Nhp2p, a putative RNA-binding protein, are present together with Gar1p in all H BOX/ACA-motif snoRNPs and constitute a common bipartite structure

Watkins, Nicholas J.; Gottschalk, Alexander; Neubauer, Gitte; Kastner, Berthold; Fabrizio, Patrizia; Mann, Matthias; Lührmann, Reinhard

doi:10.1017/s1355838298980761

Cited by 200 publications

(202 citation statements)

References 58 publications

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“…If this were the case, we would expect Shq1p and Naf1p to associate strongly and specifically with box H/ACA snoRNAs, as described previously for core proteins of box H/ACA snoRNPs (11)(12)(13)(14). To test this hypothesis, we generated chromosomal TAP-tagged versions of Shq1p and Naf1p.…”

Section: Resultsmentioning

confidence: 86%

“…The protein core of the box C/D snoRNP is composed of Nop1p, Nop58p, Nop56p, and Snu13p (9, 10) with Nop1p as the candidate methyltransferase (2). The core of the box H/ACA snoRNP contains four proteins, Gar1p, Nhp2p, Nop10p, and Cbf5p, which is presumably responsible for the pseudouridyl synthetase activity (4,(11)(12)(13)(14)(15). Although the RNA motifs required for the association of the snoRNP proteins with the box H/ACA snoRNAs have been investigated (16,17), little is known about the mechanisms by which the RNA and the protein components become assembled into mature snoRNPs.…”

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confidence: 99%

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The Shq1p·Naf1p Complex Is Required for Box H/ACA Small Nucleolar Ribonucleoprotein Particle Biogenesis

Yang¹,

Rotondo²,

Porras³

et al. 2002

Journal of Biological Chemistry

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Small nucleolar ribonucleoprotein particles (snoRNPs) are essential cofactors in ribosomal RNA metabolism. Although snoRNP composition has been thoroughly characterized, the biogenesis process of these particles is poorly understood. We have identified two proteins from the yeast Saccharomyces cerevisiae, Yil104c/Shq1p and Ynl124w/Naf1p, which are essential and required for the stability of box H/ACA snoRNPs. Depletion of either Shq1p or Naf1p leads to a dramatic and specific decrease in box H/ACA snoRNA levels in vivo. A severe concomitant defect in ribosomal RNA processing is observed, consistent with the depletion of this family of snoRNAs. Shq1p and Naf1p show nuclear localization and interact with Nhp2p and Cbf5p, two core proteins of mature box H/ACA snoRNPs. Shq1p and Naf1p form a complex, but they are not strongly associated with box H/ACA snoRNPs. We propose that Shq1p and Naf1p are involved in the early biogenesis steps of box H/ACA snoRNP assembly.

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Section: Resultsmentioning

confidence: 86%

mentioning

confidence: 99%

The Shq1p·Naf1p Complex Is Required for Box H/ACA Small Nucleolar Ribonucleoprotein Particle Biogenesis

Yang¹,

Rotondo²,

Porras³

et al. 2002

Journal of Biological Chemistry

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“…These proteins were ®rst identi®ed in budding yeast as Gar1p, Cbf5p, Nhp2p and Nop10p (Girard et al, 1992;Balakin et al, 1996;Ganot et al, 1997;Lafontaine et al, 1998;Watkins et al, 1998;Henras et al, 1998). Loss of expression of any one of these proteins results in growth arrest with aberrant rRNA, and loss of any one except Gar1p prevents the accumulation of H/ACA snoRNAs.…”

Section: Rna Accumulationmentioning

confidence: 99%

Telomerase in the human organism

2002

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The intent of this review is to describe what is known and unknown about telomerase in somatic cells of the human organism. First, we consider the telomerase enzyme. Human telomerase ribonucleoproteins undergo at least three stages of cellular biogenesis: accumulation, catalytic activation and recruitment to the telomere. Next, we describe the patterns of telomerase regulation in the human soma. Telomerase activation in some cell types appears to o set proliferation-dependent telomere shortening, delaying but not defeating the inherent mitotic clock. Finally, we elaborate the connection between telomerase misregulation and human disease, in the contexts of inappropriate telomerase activation and telomerase de®ciency. We discuss how our current perspectives on telomerase function could be applied to improving human health.

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“…Similar to other H/ACA RNAs, human telomerase RNA is stabilized by the H/ACA core proteins (Mitchell et al 1999;Dragon et al 2000;Dez et al 2001). Genetic depletion studies in yeast demonstrated that all H/ACA core proteins, except GAR1, are essential for the stability of H/ACA RNAs (BousquetAntonelli et al 1997;Henras et al 1998;Lafontaine et al 1998;Watkins et al 1998). Nevertheless, X-DC mutations have only been identified in NAP57 but none of the other core proteins (Marrone and Mason 2003).…”

Section: Protein Dynamics Of H/aca Rnpsmentioning

confidence: 99%

“…This is based on the following three observations. First, all core proteins, except GAR1, are essential for the stabilization of all H/ACA RNAs (Bousquet-Antonelli et al 1997;Henras et al 1998;Lafontaine et al 1998;Watkins et al 1998;Dez et al 2001). Second, all H/ACA RNPs can be precipitated with antibodies directed against any of the core proteins, including GAR1 (Balakin et al 1996;Ganot et al 1997).…”

Section: Introductionmentioning

confidence: 99%

Dynamic association and localization of human H/ACA RNP proteins

Kittur¹,

Darzacq²,

Roy³

et al. 2006

RNA

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Mammalian H/ACA RNPs are essential for ribosome biogenesis, pre-mRNA splicing, and telomere maintenance. To form mature RNA-protein complexes, one H/ACA RNA associates with four core proteins. In the cell, this process is assisted by at least one nuclear assembly factor, NAF1. Here we report several unanticipated dynamic aspects of H/ACA RNP proteins. First, when overexpressed, NAF1 delocalizes to the cytoplasm. However, its nucleocytoplasmic shuttling properties remain unaffected. These observations demonstrate a subtle equilibrium between NAF1 expression levels and the availability of NAF1 nuclear binding sites. Second, although NAF1 is excluded from mature RNPs in nucleoli and Cajal bodies, NAF1 associates with mature H/ACA RNA in cell lysates. This association occurs post-lysis because it is observed even when NAF1 and the H/ACA RNA are expressed in separate cells. This documents a protein-RNP association in cell lysates that is absent from intact cells. Third, in similar experiments, all H/ACA core proteins, except NAP57, exchange with their exogenous counterparts, portraying an unexpected dynamic picture of H/ACA RNPs. Finally, the irreversible association of only NAP57 with H/ACA RNA and the conundrum that only NAP57 is mutated in X-linked dyskeratosis congenita (even though most core proteins are required for maintaining H/ACA RNAs) may be more than a coincidence.

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Cbf5p, a potential pseudouridine synthase, and Nhp2p, a putative RNA-binding protein, are present together with Gar1p in all H BOX/ACA-motif snoRNPs and constitute a common bipartite structure

Abstract: Electron microscopy of purified snR42 and snR30 particles revealed that these two snoRNPs possess a similar bipartite structure that we propose to be a major structural determining principle for all H/ACA snoRNPs.

Cited by 200 publications

References 58 publications

The Shq1p·Naf1p Complex Is Required for Box H/ACA Small Nucleolar Ribonucleoprotein Particle Biogenesis

The Shq1p·Naf1p Complex Is Required for Box H/ACA Small Nucleolar Ribonucleoprotein Particle Biogenesis

Telomerase in the human organism

Dynamic association and localization of human H/ACA RNP proteins

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