title: Nuclear pre-tRNA terminal structure and RNase P recognition.
abstract: Nuclear pre-tRNA transcripts often contain an extension of the aminoacyl stem formed by base pairing between the 5'-leader and 3'-trailing sequences, but the -1 position preceding the mature 5' end is usually left unpaired. Considering recently proposed tertiary structural models for RNase P RNAs, we hypothesize that the -1 mismatch prevents a strong, coaxially extended aminoacyl stem, which might otherwise sterically interfere with substrate positioning in the RNase P active site. This hypothesis is tested by creating uninterrupted aminoacyl stem extensions in four nuclear tRNA precursors that normally have a mismatched nucleotide at position -1, and comparing their cleavage rates with those of the normal precursors. Determinations of Km and kcat values for a normal and an altered pre-tRNA(SUP53), which exhibits the most subtle structural alteration immediately upstream of the cleavage site, indicate that the mismatch at position -1 is an important structural requirement for both substrate affinity and efficient catalysis (and/or product release) by nuclear RNase P. This conclusion is further supported in vivo, where the pre-tRNA(SUP53) mutant precursor lacking the -1 mismatch is shown to accumulate.
authors.affiliation: Department of Biological Chemistry, The University of Michigan, Ann Arbor 48109-0606, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Lee
authors.forename: D W
authors.initials: DW
authors.lastname: Kindelberger
authors.forename: J Y
authors.initials: JY
authors.lastname: Lee
authors.forename: S
authors.initials: S
authors.lastname: McClennen
authors.forename: J
authors.initials: J
authors.lastname: Chamberlain
authors.forename: D R
authors.initials: DR
authors.lastname: Engelke
mesh_terms: D004722:Endoribonucleases / Q000378:metabolism*; D006868:Hydrolysis; D009690:Nucleic Acid Conformation; D012322:RNA Precursors / Q000737:chemistry* / Q000378:metabolism; D016337:RNA, Catalytic / Q000378:metabolism*; D012331:RNA, Fungal / Q000737:chemistry* / Q000378:metabolism; D012343:RNA, Transfer / Q000737:chemistry* / Q000378:metabolism; D043262:Ribonuclease P; D012441:Saccharomyces cerevisiae / Q000235:genetics; D013379:Substrate Specificity
chemical_list: D012322:RNA Precursors; D016337:RNA, Catalytic; D012331:RNA, Fungal; D012343:RNA, Transfer; D004722:Endoribonucleases; D043262:Ribonuclease P