Biochemical and genetic analysis of RNA cap guanine-N2 methyltransferases from Giardia lamblia and Schizosaccharomyces pombe

Hausmann, Stéphane; Ramı́rez, Alejandro F.; Schneider, Susanne A.; Schwer, Beate; Shuman, Stewart

doi:10.1093/nar/gkl1150

Cited by 29 publications

(54 citation statements)

References 41 publications

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“…The enzyme Tgs1 is responsible for TMG capping (Mouaikel et al 2002;Komonyi et al 2005;Lemm et al 2006;Hausmann et al 2007). Purified yeast and human Tgs1 catalyze two successive methyltransfer reactions from AdoMet to the N2 atom of guanosine nucleotides via a distributive mechanism (Hausmann and Shuman 2005a;Hausmann et al 2008;Benarroch et al 2010).…”

Section: Introductionmentioning

confidence: 99%

“…Mutational studies of several Tgs enzymes identified a suite of essential amino acid side chains that were predicted to form the binding pockets for the AdoMet donor and m 7 G acceptor (Mouaikel et al 2003;Hausmann and Shuman 2005b;Hausmann et al 2007Hausmann et al , 2008Simoes-Barbosa et al 2008;Benarroch et al 2009). Most of the substrate interactions inferred from mutational studies and modeling exercises were confirmed by the crystal structure of human Tgs1 (hTgs1) in a ternary complex with m to the triphosphate moiety of m 7 GTP ( Fig.…”

Section: Introductionmentioning

confidence: 99%

“…A genetic assessment of Tgs1 activity is complicated by the fact that Tgs1 and TMG caps are dispensable for vegetative growth of budding and fission yeast (Mouaikel et al 2002;Hausmann et al 2007). Moreover, silencing of hTgs1 by RNA i has little or no effect on the growth of HeLa cells in culture (Lemm et al 2006).…”

Section: Introductionmentioning

confidence: 99%

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Mutational analyses of trimethylguanosine synthase (Tgs1) and Mud2: Proteins implicated in pre-mRNA splicing

Chang¹,

Schwer²,

Shuman³

2010

RNA

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Yeast and human Tgs1 are orthologous RNA cap (guanine-N2) methyltransferases that convert m 7 G caps into the 2,2,7-trimethylguanosine (TMG) caps characteristic of spliceosomal snRNAs. TMG caps are dispensable for vegetative yeast growth, but are essential in the absence of Mud2, the putative yeast homolog of human splicing factor U2AF. Here we exploited the synthetic lethal interactions of tgs1D and mud2D mutations to identify essential structural features of the Tgs1 and Mud2 proteins. Thirty-two new mutations were introduced into human Tgs1 and surveyed for their effects on function in vivo in yeast and on the two sequential guanine-N2 methylation reactions in vitro. The structure-function data highlight a strictly essential p-cation interaction between Trp766 and the m 7 G base and a network of important enzymic contacts to the cap triphosphate via Lys646, Tyr771, Arg807, and Lys836. Mud2 is a 527-amino acid polypeptide composed of a hydrophilic N-terminal domain and a C-terminal RRM domain. We found that the RRM domain is necessary but not sufficient for Mud2 function in complementing growth of tgs1D mud2D and mud1D mud2D strains. Other changes in Mud2 elicited distinct phenotypes in tgs1D versus mud1D backgrounds. mud2D also caused a severe growth defect in cells lacking the Tgs1-binding protein encoded by the nonessential gene YNR004w (now renamed SWM2, synthetic with mud2D). Mud2 mutational effects in the swm2D background paralleled those for mud1D. The requirements for Mud2 function are apparently more stringent when yeast cells lack TMG caps than when they lack Mud1 or Swm2.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Mutational analyses of trimethylguanosine synthase (Tgs1) and Mud2: Proteins implicated in pre-mRNA splicing

Chang¹,

Schwer²,

Shuman³

2010

RNA

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“…In yeast, TGS1 hypermethylates the m7G RNA cap to a trimethylguanosine (TMG; m 2,2,7 guanosine) cap (28,(33)(34)(35)(36)(37). A nuclear isoform of human PIMT has been shown to have methyl transferase activity (30)(31)(32).…”

mentioning

confidence: 99%

Trimethylguanosine capping selectively promotes expression of Rev-dependent HIV-1 RNAs

Yedavalli

Jeang

2010

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

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5′-mRNA capping is an early modification that affects pre-mRNA synthesis/splicing, RNA cytoplasmic transport, and mRNA translation and turnover. In eukaryotes, a 7-methylguanosine (m7G) cap is added to newly transcribed RNA polymerase II (RNAP II) transcripts. A subset of RNAP II-transcribed cellular RNAs, including small nuclear RNA (snRNA), small nucleolar RNA (snoRNA), and telomerase RNA, is further hypermethylated at the exocyclic N2 of the guanosine to create a trimethylguanosine (TMG)-capped RNA. Some of these TMG-capped RNAs are transported within the nucleus and from the nucleus to the cytoplasm by the CRM-1 (required for chromosome region maintenance) protein. CRM-1 is also used to export Rev/RRE-dependent unspliced/ partially spliced HIV-1 RNAs. Here we report that like snRNAs and snoRNAs, some Rev/RRE-dependent HIV-1 RNAs are TMG-capped. The methyltransferase responsible for TMG modification of HIV-1 RNAs is the human PIMT (peroxisome proliferator-activated receptor-interacting protein with methyltransferase) protein. TMG capping of unspliced/partially spliced HIV-1 RNAs represents a new regulatory mechanism for selective expression.required for chromosome region maintenance | RNA export | peroxisome proliferator-activated receptor-interacting protein with methyltransferase P osttranscriptional processing of RNA plays a critical role in gene expression (1-3). An early mRNA modification is the formation of a 7-methylguanosine (m7G) cap (4-6). In mammals, the acquisition of an m7G cap requires two enzymes (7-9), a capping enzyme (triphosphatase and guanylyltransferase activity) and an RNA-(guanine 7)-methyltransferase. These proteins are essential for cell growth, and mutations in the triphosphatase, guanylyltransferase, or methyltransferase components of the capping apparatus are lethal in vivo (10).Cellular RNAP II transcripts are mostly m7G-capped (1-3, 11). An m7G cap facilitates the initiation of translation in mammalian cells, and a failure to cap premRNAs results in their accelerated decay by 5′ exoribonuclease degradation (2,(12)(13)(14). Capping of viral RNAs has been less extensively investigated. It has been generally assumed that like cellular RNAs, many viral RNAs have a 5′ m7G cap, and that viruses either use the cellular capping machinery (e.g., viruses that replicate in the nucleus) or encode their own capping enzymes (e.g., viruses that replicate in the cytoplasm) (15, 16). Interestingly, there is a surprisingly diverse range of cap modifications; for instance, Mimivirus, a large DNA virus of amoeba, encodes an RNA cap guanine-N2 methyltransferase that hypermethylates the viral RNA cap (17); influenza virus "snatches" caps from cellular mRNAs (18, 19); West Nile fever virus has two methyl additions on its RNA cap (20); Sindbis virus produces mRNAs that have dimethylguanosine and trimethylguanosine caps [hypermethylated caps/m 2,2,7 G caps (21)]; and Semliki forest virus late mRNAs also have hypermethylated caps (22). On the other hand, poliovirus, encephalomyelitis virus, foot and mouth...

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“…TGS1 hypermethylates the m7G RNA cap to a trimethylguanosine (TMG; m2,2,7 guanosine) cap. [28][29][30][31][32][33] A nuclear isoform of human PIMT has been shown to have methyl transferase activity. 28,34,35 In the new finding, PIMT was found to hypermethylate selectively the RNA-cap of unspliced and partially spliced HIV-1 transcripts and to increase their cytoplasmic distribution 23 ( Fig.…”

Section: What Does Pimt Do For Hiv-1 Rna?mentioning

confidence: 99%

Rev-ing up post-transcriptional HIV-1 RNA expression

Yedavalli

Jeang

2011

RNA Biology

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Biochemical and genetic analysis of RNA cap guanine-N2 methyltransferases from Giardia lamblia and Schizosaccharomyces pombe

Cited by 29 publications

References 41 publications

Mutational analyses of trimethylguanosine synthase (Tgs1) and Mud2: Proteins implicated in pre-mRNA splicing

Mutational analyses of trimethylguanosine synthase (Tgs1) and Mud2: Proteins implicated in pre-mRNA splicing

Trimethylguanosine capping selectively promotes expression of Rev-dependent HIV-1 RNAs

Rev-ing up post-transcriptional HIV-1 RNA expression

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