Hypermethylation of the Cap Structure of Both Yeast snRNAs and snoRNAs Requires a Conserved Methyltransferase that Is Localized to the Nucleolus

Mouaikel, John; Verheggen, Céline; Bertrand, Édouard; Tazi, Jamal; Bordonne, Rémy

doi:10.1016/s1097-2765(02)00484-7

Cited by 221 publications

(368 citation statements)

References 44 publications

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“…The hypothesis that Giardia caps its RNAs is also consistent with an early study identifying several small RNAs in Giardia that reacted with antibody to the 2,2,7-trimethylguanosine (TMG) cap; the TMG-capped species were tentatively identified as Giardia snRNAs with possible roles in RNA processing (26). Available evidence suggests that TMG caps are formed by post-transcriptional N2-methylation of the standard m 7 GpppN cap (27). In this light, it is noteworthy that Giardia encodes a putative homolog of the yeast TMG cap synthase, Tgs1 (data not shown).…”

Section: Fig 7 5-race Analysis Of Giardia Transcriptssupporting

confidence: 72%

Yeast-like mRNA Capping Apparatus in Giardia lamblia

Hausmann

Altura

Witmer

et al. 2005

Journal of Biological Chemistry

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A scheme of eukaryotic phylogeny has been suggested based on the structure and physical linkage of the RNA triphosphatase and RNA guanylyltransferase enzymes that catalyze mRNA cap formation. Here we show that the unicellular pathogen Giardia lamblia encodes an mRNA capping apparatus consisting of separate triphosphatase and guanylyltransferase components, which we characterize biochemically. We also show that native Giardia mRNAs have blocked 5-ends and that 7-methylguanosine caps promote translation of transfected mRNAs in Giardia in vivo. The Giardia triphosphatase belongs to the tunnel family of metal-dependent phosphohydrolases that includes the RNA triphosphatases of fungi, microsporidia, and protozoa such as Plasmodium and Trypanosoma. The tunnel enzymes adopt a unique active-site fold and are structurally and mechanistically unrelated to the cysteine-phosphatase-type RNA triphosphatases found in metazoans and plants, which comprise part of a bifunctional triphosphataseguanylyltransferase fusion protein. All available evidence now points to the separate tunnel-type triphosphatase and guanylyltransferase as the aboriginal state of the capping apparatus. We identify a putative tunneltype triphosphatase and a separate guanylyltransferase encoded by the red alga Cyanidioschyzon merolae. These findings place fungi, protozoa, and red algae in a common lineage distinct from that of metazoa and plants. The m7 GpppN cap is a defining feature of eukaryotic mRNA that is formed via three enzymatic reactions: (i) the 5Ј-triphosphate end of the pre-mRNA is hydrolyzed to a diphosphate by RNA triphosphatase; (ii) the diphosphate RNA end is capped with GMP by RNA guanylyltransferase; and (iii) the GpppN cap is methylated by RNA (guanine-N7) methyltransferase (1). Capping enzymes are a good focal point for considering eukaryotic evolution, because the cap structure is thought to be ubiquitous in eukaryotic organisms but absent from the bacterial and archaeal domains of life. Thus, any differences in the capping apparatus between eukaryal taxa would reflect events that post-date the emergence of ancestral nucleated cells. Previously, we proposed a scheme of eukaryotic phylogeny based on two features of the mRNA capping apparatus: the structure and mechanism of the triphosphatase component (metal-dependent fungal-type versus metal-independent cysteine-phosphatase type) and whether the triphosphatase is covalently fused to the guanylyltransferase component (2, 3).Metazoans and plants have a two-component capping system consisting of a bifunctional triphosphatase-guanylyltransferase polypeptide and a separate methyltransferase polypeptide, whereas fungi, microsporidia, and protozoa (e.g. Plasmodium falciparum and Trypanosoma brucei) have a three-component system consisting of separate triphosphatase, guanylyltransferase, and methyltransferase polypeptides (2, 4, 5). The primary structures and biochemical mechanisms of the fungal and mammalian guanylyltransferases and cap methyltransferases are conserved. However, the atomic st...

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Section: Fig 7 5-race Analysis Of Giardia Transcriptssupporting

confidence: 72%

Yeast-like mRNA Capping Apparatus in Giardia lamblia

Hausmann

Altura

Witmer

et al. 2005

Journal of Biological Chemistry

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“…These include a rat homologue of human MORF, which is a histone acetyltransferase (32), DNA Mtase, a DNA (cytosine-5) methyltransferase (47), TAF II 140 (48), CTIP͞RB-8 (a retinoblastoma-binding protein) (49), PIMT, an RNA methyltransferase (15,24,50), PRIC215, and PRIC177 (Fig. 1).…”

Section: Discussionmentioning

confidence: 99%

Identification of a transcriptionally active peroxisome proliferator-activated receptor α-interacting cofactor complex in rat liver and characterization of PRIC285 as a coactivator

Surapureddi

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

126

120

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Peroxisome proliferator-activated receptor ␣ (PPAR␣) plays a central role in the cell-specific pleiotropic responses induced by structurally diverse synthetic chemicals designated as peroxisome proliferators. Transcriptional regulation by liganded nuclear receptors involves the participation of cofactors that form multiprotein complexes to achieve cell-and gene-specific transcription. Here we report the identification of such a transcriptionally active PPAR␣-interacting cofactor (PRIC) complex from rat liver nuclear extracts that interacts with full-length PPAR␣ in the presence of ciprofibrate, a synthetic ligand, and leukotriene B 4, a natural ligand. The liganded PPAR␣-PRIC complex enhanced transcription from a peroxisomal enoyl-CoA hydratase͞L-3-hydroxyacyl-CoA dehydrogenase bifunctional enzyme gene promoter template that contains peroxisome proliferator response elements. Rat liver PRIC complex comprises some 25 polypeptides, and their identities were established by mass spectrometry and limited sequence analysis. Eighteen of these peptides contain one or more LXXLL motifs necessary for interacting with nuclear receptors. PRIC complex includes known coactivators or coactivator-binding proteins (CBP, SRC-1, PBP, PRIP, PIMT, TRAP100, SUR-2, and PGC-1), other proteins that have not previously been described in association with transcription complexes (CHD5, TOG, and MORF), and a few novel polypeptides designated PRIC300, -285, -215, -177, and -145. We describe the cDNA for PRIC285, which contains five LXXLL motifs. It interacts with PPAR␣ and acts as a coactivator by moderately stimulating PPAR␣-mediated transcription in transfected cells. We conclude that liganded PPAR␣ recruits a distinctive multiprotein complex from rat liver nuclear extracts. The composition of this complex may provide insight into the basis of tissue and species sensitivity to peroxisome proliferators.

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“…53 A properly assembled Sm core is required for cap hypermethylation and 3 0 -end maturation. [54][55][56] Tgs1 directly interacts with SMN both in vivo and in vitro.…”

Section: Smn and Cytoplasmic Snrnp Assemblymentioning

confidence: 99%

SMN - A chaperone for nuclear RNP social occasions?

2016

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Survival Motor Neuron (SMN) protein localizes to both the nucleus and the cytoplasm. Cytoplasmic SMN is diffusely localized in large oligomeric complexes with core member proteins, called Gemins. Biochemical and cell biological studies have demonstrated that the SMN complex is required for the cytoplasmic assembly and nuclear transport of Sm-class ribonucleoproteins (RNPs). Nuclear SMN accumulates with spliceosomal small nuclear (sn)RNPs in Cajal bodies, sub-domains involved in multiple facets of snRNP maturation. Thus, the SMN complex forms stable associations with both nuclear and cytoplasmic snRNPs, and plays a critical role in their biogenesis. In this review, we focus on potential functions of the nuclear SMN complex, with particular emphasis on its role within the Cajal body.

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Hypermethylation of the Cap Structure of Both Yeast snRNAs and snoRNAs Requires a Conserved Methyltransferase that Is Localized to the Nucleolus

Cited by 221 publications

References 44 publications

Yeast-like mRNA Capping Apparatus in Giardia lamblia

Yeast-like mRNA Capping Apparatus in Giardia lamblia

Identification of a transcriptionally active peroxisome proliferator-activated receptor α-interacting cofactor complex in rat liver and characterization of PRIC285 as a coactivator

SMN - A chaperone for nuclear RNP social occasions?

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