The Role of the<i>Schizosaccharomyces pombe</i>gar2 Protein in Nucleolar Structure and Function Depends on the Concerted Action of its Highly Charged N Terminus and its RNA-binding Domains

Sicard, Hélène; Faubladier, Marlène; Noaillac-Depeyre, Jacqueline; Léger-Silvestre, Isabelle; Gas, Nicole; Caizergues‐Ferrer, Michèle

doi:10.1091/mbc.9.8.2011

Cited by 22 publications

(11 citation statements)

References 73 publications

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“…The nucleolus is the site of ribosome biogenesis, and, in wild-type conditions, its size and morphology directly correlates with ribosome production activity (92,93). In genetically altered background, increase in nucleolus size can be a direct consequence of pre-ribosomal RNA processing or ribosome assembly alteration (89,94,95), or can indirectly result in the alteration of other cellular processes interconnected with nucleolar functions (96,97) as this is probably the case in titan and plz mutants which display, in addition to nucleolar hypertrophy, cell cycle and cytokinesis defects (90,91,98,99). In this case, however, we know that the La protein is likely to be important for ribosome biogenesis.…”

Section: Discussionmentioning

confidence: 99%

A bona fide La protein is required for embryogenesis in Arabidopsis thaliana

Fleurdépine¹,

Deragon²,

Devic³

et al. 2007

Nucleic Acids Research

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Searches in the Arabidopsis thaliana genome using the La motif as query revealed the presence of eight La or La-like proteins. Using structural and phylogenetic criteria, we identified two putative genuine La proteins (At32 and At79) and showed that both are expressed throughout plant development but at different levels and under different regulatory conditions. At32, but not At79, restores Saccharomyces cerevisiae La nuclear functions in non-coding RNAs biogenesis and is able to bind to plant 3′-UUU-OH RNAs. We conclude that these La nuclear functions are conserved in Arabidopsis and supported by At32, which we renamed as AtLa1. Consistently, AtLa1 is predominantly localized to the plant nucleoplasm and was also detected in the nucleolar cavity. The inactivation of AtLa1 in Arabidopsis leads to an embryonic-lethal phenotype with deficient embryos arrested at early globular stage of development. In addition, mutant embryonic cells display a nucleolar hypertrophy suggesting that AtLa1 is required for normal ribosome biogenesis. The identification of two distantly related proteins with all structural characteristics of genuine La proteins suggests that these factors evolved to a certain level of specialization in plants. This unprecedented situation provides a unique opportunity to dissect the very different aspects of this crucial cellular activity.

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Section: Discussionmentioning

confidence: 99%

A bona fide La protein is required for embryogenesis in Arabidopsis thaliana

Fleurdépine¹,

Deragon²,

Devic³

et al. 2007

Nucleic Acids Research

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“…Fluorescein isothiocyanate-conjugated anti-mouse Nop1p antibodies were diluted 1/200 in phosphate-buffered saline containing 1% bovine serum albumin (3). For Gar1p, the experimental and wild-type cells were transformed with a plasmid expressing a Gar1-GFP fusion protein (62). Transformants were processed as described above, except that growth was in medium lacking histidine and uracil.…”

Section: Methodsmentioning

confidence: 99%

A Well-Connected and Conserved Nucleoplasmic Helicase Is Required for Production of Box C/D and H/ACA snoRNAs and Localization of snoRNP Proteins

King

Decatur

Bertrand

et al. 2001

Molecular and Cellular Biology

102

107

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Synthesis of small nucleolar RNA protein complexes (snoRNPs) occurs in several stages, which are almost certainly overlapping (for recent summaries, see references 66 and 81). The major phases include (i) synthesis of the snoRNA and protein components, (ii) assembly of the snoRNP, and (iii) movement of the particle to the nucleolar complex, perhaps by way of Cajal bodies (22,45,54,58). In metazoans, most snoRNAs are derived from introns of protein genes, and all of the assembly steps are believed to occur in the nucleoplasm. In Saccharomyces cerevisiae, most snoRNAs are transcribed from independent genes; however, a few are encoded in introns (81). Processing of the pre-snoRNAs in yeast is coupled to mRNA splicing (50, 53), and this situation likely pertains to metazoans as well.Successful progression of the snoRNA transcript through each biosynthetic stage depends on the box C/D and H/ACA sequences used to classify the two large families of snoRNPs (see, e.g., references 8, 13, 14, 19, 27, 38, 39, 44, 45, 58, 64, and 79). In vivo function studies have shown that the binding of proteins to the motifs defined by the box elements is essential for proper processing of the snoRNA (end formation) and its localization to the nucleolus, presumably as a nascent snoRNP (reviewed in references 35, 66, and 81). Current models propose that protein binding to these motifs may be the first step in snoRNP assembly. Notably, the box elements are also intimately involved in the two types of nucleotide modification reaction mediated by the snoRNPs, i.e., ribose methylation by the C/D snoRNPs and pseudouridine formation by the H/ACA snoRNPs (4-6, 18, 34, 47, 66).The final list of factors involved in snoRNP synthesis and function will probably be quite extensive. For example snoRNA processing involves several nucleases, some of which also participate in the processing of rRNA, other small RNAs, and pre-mRNA (72; see also references 2, 15, 16, and 71).

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“…For this mutant, there is a correlation between large nucleoli and the enhanced ribosome formation. On the contrary, deletion of the RNA‐binding domain of the GAR2 gene in S. pombe causes strong inhibition of 18S RNA accumulation and an hypertrophy of the nucleolus (Sicard et al. , 1998).…”

Section: Mutation In Domino1 Affects Nucleolar Functionsmentioning

confidence: 99%

DOMINO1, a member of a small plant‐specific gene family, encodes a protein essential for nuclear and nucleolar functions

et al. 2004

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). † Present address: MEDICAGO -Usine de molé cules recombinantes, 1020 route de l'Eglise, Sainte Foy, Quebec, Canada. SummaryArabidopsis embryos carrying the domino1 mutation grow slowly in comparison with wild type embryos and as a consequence reach only the globular stage at desiccation. The primary defect of the mutation at the cellular level is the large size of the nucleolus that can be observed soon after fertilization in the nuclei of both the embryo and the endosperm. The ultrastructure of mutant nucleoli is drastically different from wild type and points to a fault in ribosome biogenesis. DOMINO1 encodes a protein, which belongs to a plant-specific gene family sharing a common motif of unknown function, present in the tomato DEFECTIVE CHLOROPLASTS AND LEAVES (LeDCL) protein. Using a GFP protein fusion, we show that DOMINO1 is targeted to the nucleus. We propose that inactivation of DOMINO1 has a negative effect on ribosome biogenesis and on the rate of cell division.

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The Role of theSchizosaccharomyces pombegar2 Protein in Nucleolar Structure and Function Depends on the Concerted Action of its Highly Charged N Terminus and its RNA-binding Domains

Cited by 22 publications

References 73 publications

A bona fide La protein is required for embryogenesis in Arabidopsis thaliana

A bona fide La protein is required for embryogenesis in Arabidopsis thaliana

A Well-Connected and Conserved Nucleoplasmic Helicase Is Required for Production of Box C/D and H/ACA snoRNAs and Localization of snoRNP Proteins

DOMINO1, a member of a small plant‐specific gene family, encodes a protein essential for nuclear and nucleolar functions

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