title: Self-association of Trimethylguanosine Synthase Tgs1 is required for efficient snRNA/snoRNA trimethylation and pre-rRNA processing.
abstract: Trimethylguanosine Synthase catalyses transfer of two methyl groups to the m(7)G cap of RNA polymerase II transcribed snRNAs, snoRNAs, and telomerase RNA TLC1 to form a 2,2,7-trimethylguanosine cap. While in vitro studies indicate that Tgs1 functions as a monomer and the dimethylation of m(7)G caps is not a processive reaction, partially methylated sn(o)RNAs are typically not detected in living cells. Here we show that both yeast and human Tgs1p possess a conserved self-association property located at the N-terminus. A disruption of Tgs1 self-association led to a strong reduction of sn(o)RNA trimethylation as well as reduced nucleolar enrichment of Tgs1. Self-association of Tgs1p and its catalytic activity were also prerequisite to bypass the requirement for its accessory factor Swm2p for efficient pre-rRNA processing and snRNA trimethylation. The ability to self-associate might enable Tgs1 to efficiently dimethylate the caps of the targeted RNAs in vivo.
authors.affiliation: 1] Biochemistry Center (BZH), University of Heidelberg, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany [2] Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Goettingen, Germany.
authors.forename: Kum-Loong
authors.initials: KL
authors.lastname: Boon
authors.affiliation: Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Goettingen, Germany.
authors.forename: Michael David
authors.initials: MD
authors.lastname: Pearson
authors.affiliation: Biochemistry Center (BZH), University of Heidelberg, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Koš
mesh_terms: D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D006151:Guanosine / Q000031:analogs & derivatives / Q000096:biosynthesis; D006801:Humans; D008745:Methylation; D008780:Methyltransferases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012322:RNA Precursors / Q000235:genetics* / Q000378:metabolism; D012326:RNA Splicing; D020537:RNA, Small Nucleolar / Q000235:genetics* / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D014158:Transcription, Genetic
chemical_list: D002352:Carrier Proteins; D012322:RNA Precursors; D020537:RNA, Small Nucleolar; D011994:Recombinant Proteins; C552114:SWM2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D006151:Guanosine; C017778:N(2),N(2),7-trimethylguanosine; D008780:Methyltransferases; C456271:trimethylguanosine synthase