title: Precursors of tRNAs are stabilized by methylguanosine cap structures.
abstract: Efficient maturation of transfer RNAs (tRNAs) is required for rapid cell growth. However, the precise timing of tRNA processing in coordination with the order of tRNA modifications has not been thoroughly elucidated. To analyze the modification status of tRNA precursors (pre-tRNAs) during maturation, we isolated pre-tRNAs at various stages from Saccharomyces cerevisiae and subjected them to MS analysis. We detected methylated guanosine cap structures at the 5' termini of pre-tRNAs bearing 5' leader sequences. These capped pre-tRNAs accumulated substantially after inhibition of RNase P activity. Upon depletion of the capping enzyme Ceg1p, the steady state level of capped pre-tRNA was markedly reduced. In addition, a population of capped pre-tRNAs accumulated in strains in which 5' exonucleases were inhibited, indicating that the 5' cap structures protect pre-tRNAs from 5'-exonucleolytic degradation during maturation.
authors.affiliation: Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, Tokyo, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Ohira
authors.affiliation: Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, Tokyo, Japan.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Suzuki
mesh_terms: D005092:Exonucleases / Q000037:antagonists & inhibitors / Q000378:metabolism; D006151:Guanosine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D009713:Nucleotidyltransferases / Q000172:deficiency / Q000235:genetics; D012315:RNA Caps / Q000737:chemistry* / Q000378:metabolism*; D012322:RNA Precursors / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D020871:RNA Stability; D012343:RNA, Transfer / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D043262:Ribonuclease P / Q000037:antagonists & inhibitors / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000201:enzymology / Q000235:genetics; D000098556:mRNA Guanylyltransferases
chemical_list: C116616:8-methylguanosine; D012315:RNA Caps; D012322:RNA Precursors; D006151:Guanosine; D012343:RNA, Transfer; D009713:Nucleotidyltransferases; D000098556:mRNA Guanylyltransferases; D005092:Exonucleases; D043262:Ribonuclease P