title: Rex1p deficiency leads to accumulation of precursor initiator tRNAMet and polyadenylation of substrate RNAs in Saccharomyces cerevisiae.
abstract: A synthetic genetic array was used to identify lethal and slow-growth phenotypes produced when a mutation in TRM6, which encodes a tRNA modification enzyme subunit, was combined with the deletion of any non-essential gene in Saccharomyces cerevisiae. We found that deletion of the REX1 gene resulted in a slow-growth phenotype in the trm6-504 strain. Previously, REX1 was shown to be involved in processing the 3' ends of 5S rRNA and the dimeric tRNA(Arg)-tRNA(Asp). In this study, we have discovered a requirement for Rex1p in processing the 3' end of tRNA(i)(Met) precursors and show that precursor tRNA(i)(Met) accumulates in a trm6-504 rex1Delta strain. Loss of Rex1p results in polyadenylation of its substrates, including tRNA(i)(Met), suggesting that defects in 3' end processing can activate the nuclear surveillance pathway. Finally, purified Rex1p displays Mg(2+)-dependent ribonuclease activity in vitro, and the enzyme is inactivated by mutation of two highly conserved amino acids.
authors.affiliation: Department of Biological Sciences, Marquette University, Milwaukee, WI, USA.
authors.forename: Sarah G
authors.initials: SG
authors.lastname: Ozanick
authors.forename: Xuying
authors.initials: X
authors.lastname: Wang
authors.forename: Michael
authors.initials: M
authors.lastname: Costanzo
authors.forename: Renee L
authors.initials: RL
authors.lastname: Brost
authors.forename: Charles
authors.initials: C
authors.lastname: Boone
authors.forename: James T
authors.initials: JT
authors.lastname: Anderson
mesh_terms: D039621:Eukaryotic Initiation Factor-3 / Q000235:genetics; D005095:Exoribonucleases / Q000235:genetics / Q000502:physiology*; D017353:Gene Deletion; D026723:Polyadenylation; D026721:RNA 3' End Processing; D012322:RNA Precursors / Q000737:chemistry / Q000378:metabolism*; D012341:RNA, Ribosomal, 5S / Q000737:chemistry / Q000378:metabolism; D012343:RNA, Transfer / Q000737:chemistry / Q000378:metabolism; D012347:RNA, Transfer, Arg / Q000737:chemistry / Q000378:metabolism; D012358:RNA, Transfer, Met / Q000737:chemistry / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000502:physiology*; D012359:tRNA Methyltransferases
chemical_list: D039621:Eukaryotic Initiation Factor-3; D012322:RNA Precursors; D012341:RNA, Ribosomal, 5S; D012347:RNA, Transfer, Arg; D012358:RNA, Transfer, Met; D029701:Saccharomyces cerevisiae Proteins; D012343:RNA, Transfer; C409023:Gcd10 protein, S cerevisiae; D012359:tRNA Methyltransferases; D005095:Exoribonucleases; C529500:Rex1 exonuclease, S cerevisiae