title: Deletion of Swm2p selectively impairs trimethylation of snRNAs by trimethylguanosine synthase (Tgs1p).
abstract: The 5' cap trimethylation of small nuclear (snRNAs) and several nucleolar RNAs (snoRNAs) by trimethylguanosine synthase 1 (Tgs1p) is required for efficient pre-mRNA splicing. The previously uncharacterised protein Swm2p interacted with Tgs1p in yeast two-hybrid screens. In the present study we show that Swm2p interacts with the N-terminus of Tgs1p and its deletion impairs pre-mRNA splicing and pre-rRNA processing. The trimethylation of spliceosomal snRNAs and the U3 snoRNA, but not other snoRNAs, was abolished in the absence of Swm2p, indicating that Swm2p is required for a substrate-specific activity of Tgs1p.
authors.affiliation: Biochemistry Center (BZH), University of Heidelberg, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany. kum-loong.boon@bzh.uni-heidelberg.de
authors.forename: Kum-Loong
authors.initials: KL
authors.lastname: Boon
authors.forename: Martin
authors.initials: M
authors.lastname: Kos
mesh_terms: D002352:Carrier Proteins / Q000378:metabolism*; D002466:Cell Nucleolus / Q000378:metabolism; D017353:Gene Deletion; D008745:Methylation; D008780:Methyltransferases / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D026721:RNA 3' End Processing / Q000235:genetics; D012322:RNA Precursors / Q000235:genetics; D012326:RNA Splicing / Q000235:genetics; D012342:RNA, Small Nuclear / Q000378:metabolism*; D020537:RNA, Small Nucleolar / Q000378:metabolism; D054682:Ribosome Subunits, Small, Eukaryotic / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D002352:Carrier Proteins; D012322:RNA Precursors; D012342:RNA, Small Nuclear; D020537:RNA, Small Nucleolar; C552114:SWM2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D008780:Methyltransferases; C456271:trimethylguanosine synthase