Genetic and biochemical analysis of yeast and human cap trimethylguanosine synthase: Functional overlap of 2,2,7-trimethylguanosine caps, small nuclear ribonucleoprotein components, PRE-mRNA splicing factors, and RNA decay pathways Journal Article

   

Authors:	Hausmann, S.; Zheng, S.; Costanzo, M.; Brost, R. L.; Garcin, D.; Boone, C.; Shuman, S.; Schwer, B.
Article Title:	Genetic and biochemical analysis of yeast and human cap trimethylguanosine synthase: Functional overlap of 2,2,7-trimethylguanosine caps, small nuclear ribonucleoprotein components, PRE-mRNA splicing factors, and RNA decay pathways
Abstract:	Trimethylguanosine synthase (Tgs1) is the enzyme that converts standard m7G caps to the 2,2,7-trimethylguanosine (TMG) caps characteristic of spliceosomal small nuclear RNAs. Fungi and mammalian somatic cells are able to grow in the absence of Tgs1 and TMG caps, suggesting that an essential function of the TMG cap might be obscured by functional redundancy. A systematic screen in budding yeast identified nonessential genes that, when deleted, caused synthetic growth defects with tgs1Δ. The Tgs1 interaction network embraced proteins implicated in small nuclear ribonucleoprotein function and spliceosome assembly, including Mud2, Nam8, Brr1, Lea1, Ist3, Isy1, Cwc21, and Bud13. Complementation of the synthetic lethality of mud2Δ tgs1Δ and nam8Δ tgs1Δ strains by wild-type TGS1, but not by catalytically defective mutants, indicated that the TMG cap is essential for mitotic growth when redundant splicing factors are missing. Our genetic analysis also highlighted synthetic interactions of Tgs1 with proteins implicated in RNA end processing and decay (Pat1, Lsm1, and Trf4) and regulation of polymerase II transcription (Rpn4, Spt3, Srb2, Soh1, Swr1, and Htz1). We find that the C-terminal domain of human Tgs1 can function in lieu of the yeast protein in vivo. We present a biochemical characterization of the human Tgs1 guanine-N 2 methyltransferase reaction and identify individual amino acids required for methyltransferase activity in vitro and in vivo. © 2008 by The American Society for Biochemistry and Molecular Biology, Inc.
Keywords:	unclassified drug; gene deletion; mutation; nonhuman; genetic analysis; protein domain; protein function; proteins; phenotype; mammalia; carboxy terminal sequence; protein; genetic transcription; protein interaction; enzyme activity; rna; methyltransferase; amines; methyltransferases; amino acid sequence; molecular sequence data; sequence homology, amino acid; saccharomyces cerevisiae; guanosine; sequence alignment; nucleic acids; substrate specificity; transcription; in-vivo; models, molecular; protein structure, tertiary; yeast; saccharomycetales; amino acids; organic acids; mammals; biochemistry; catalytic domain; small nuclear ribonucleoprotein; fungi; enzymes; rna splicing; in vitro; rna polymerase; genome, fungal; nuclear ribonucleoprotein; guanosine diphosphate; probability density function; synthetase; growth defects; synthase; interaction networks; biochemical phenomena; biochemical analysis; flow interactions; functions; growth (materials); biochemical characterizations; budding yeasts; complementation; functional redundancies; genetic analyses; methyl transferases; methyltransferase activities; mitotic growths; mrna splicing; rna decays; somatic cells; spliceosome assemblies; splicing factors; terminal domains; yeast proteins; 2,2,7 trimethylguanosine cap; cap trimethylguanosine synthase; guanine n 2 methyltransferase; htz1 protein; lsm1 protein; pat1 protein; rpn4 protein; soh1 protein; spt3 protein; srb2 protein; swr1 protein; telomeric repeat binding factor 4; ribonucleoproteins, small nuclear
Journal Title:	Journal of Biological Chemistry
Volume:	283
Issue:	46
ISSN:	0021-9258
Publisher:	American Society for Biochemistry and Molecular Biology
Date Published:	2008-11-14
Start Page:	31706
End Page:	31718
Language:	English
DOI:	10.1074/jbc.M806127200
PUBMED:	18775984
PROVIDER:	scopus
PMCID:	PMC2581544
DOI/URL:	http://www.scopus.com/inward/record.url?eid=2-s2.0-57649120781&partnerID=40&md5=f5e3edb35ccd6acfd184c7928152812d
Notes:	--- - "Cited By (since 1996): 18" - "Export Date: 17 November 2011" - "CODEN: JBCHA" - "Source: Scopus"

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