Biomaterial Database

A conditional lethal yeast phosphotransferase (tpt1) mutant accumulates tRNAs with a 2'-phosphate and an undermodified base at the splice junction. 1997

S L Spinelli, and S A Consaul, and E M Phizicky

Department of Biochemistry and Biophysics, University of Rochester School of Medicine, New York 14642, USA.

tRNA splicing is essential in yeast and humans and presumably all eukaryotes. The first two steps of yeast tRNA splicing, excision of the intron by endonuclease and joining of the exons by tRNA ligase, leave a splice junction bearing a 2'-phosphate. Biochemical analysis suggests that removal of this phosphate in yeast is catalyzed by a highly specific 2'-phosphotransferase that transfers the phosphate to NAD to form ADP-ribose 1"-2" cyclic phosphate. 2'-Phosphotransferase catalytic activity is encoded by a single essential gene, TPT1, in the yeast Saccharomyces cerevisiae. We show here that Tpt1 protein is responsible for the dephosphorylation step of tRNA splicing in vivo because, during nonpermissive growth, conditional lethal tpt1 mutants accumulate 2'-phosphorylated tRNAs from eight different tRNA species that are known to be spliced. We show also that several of these tRNAs are undermodified at the splice junction residue, which is always located at the hypermodified position one base 3' of the anticodon. This result is consistent with previous results indicating that modification of the hypermodified position occurs after intron excision in the tRNA processing pathway, and implies that modification normally follows the dephosphorylation step of tRNA splicing in vivo.

UI	MeSH Term	Description	Entries
D008956	Models, Chemical	Theoretical representations that simulate the behavior or activity of chemical processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment.	Chemical Models,Chemical Model,Model, Chemical
D009154	Mutation	Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.	Mutations
D005800	Genes, Fungal	The functional hereditary units of FUNGI.	Fungal Genes,Fungal Gene,Gene, Fungal
D005804	Genes, Lethal	Genes whose loss of function or gain of function MUTATION leads to the death of the carrier prior to maturity. They may be essential genes (GENES, ESSENTIAL) required for viability, or genes which cause a block of function of an essential gene at a time when the essential gene function is required for viability.	Alleles, Lethal,Allele, Lethal,Gene, Lethal,Lethal Allele,Lethal Alleles,Lethal Gene,Lethal Genes
D000090324	Tumor Protein, Translationally-Controlled 1	A highly expressed protein in tumor cells, encoded by Tpt1 gene. It's involved in various cellular activities including protein synthesis, calcium-binding, MICROTUBULE stabilization, growth, and cell survival. Also, Tpt1 identified as a direct target gene of P53 tumor suppression.	Histamine Releasing Factor,Histamine Releasing Factor, Lymphocyte-Dependent,Histamine-Releasing Factor (IgE-Dependent),Protein P23, Ehrlich Ascites Tumor,TPT1 Protein,Translationally-Controlled Tumor Protein,Factor, Histamine Releasing,Histamine Releasing Factor, Lymphocyte Dependent,Protein, TPT1,Protein, Translationally-Controlled Tumor,Translationally Controlled Tumor Protein,Tumor Protein, Translationally Controlled 1,Tumor Protein, Translationally-Controlled
D012265	Ribonucleotides	Nucleotides in which the purine or pyrimidine base is combined with ribose. (Dorland, 28th ed)	Ribonucleoside Phosphates,Ribonucleotide,Phosphates, Ribonucleoside
D012326	RNA Splicing	The ultimate exclusion of nonsense sequences or intervening sequences (introns) before the final RNA transcript is sent to the cytoplasm.	RNA, Messenger, Splicing,Splicing, RNA,RNA Splicings,Splicings, RNA
D012331	RNA, Fungal	Ribonucleic acid in fungi having regulatory and catalytic roles as well as involvement in protein synthesis.	Fungal RNA
D012343	RNA, Transfer	The small RNA molecules, 73-80 nucleotides long, that function during translation (TRANSLATION, GENETIC) to align AMINO ACIDS at the RIBOSOMES in a sequence determined by the mRNA (RNA, MESSENGER). There are about 30 different transfer RNAs. Each recognizes a specific CODON set on the mRNA through its own ANTICODON and as aminoacyl tRNAs (RNA, TRANSFER, AMINO ACYL), each carries a specific amino acid to the ribosome to add to the elongating peptide chains.	Suppressor Transfer RNA,Transfer RNA,tRNA,RNA, Transfer, Suppressor,Transfer RNA, Suppressor,RNA, Suppressor Transfer
D012356	RNA, Transfer, Leu	A transfer RNA which is specific for carrying leucine to sites on the ribosomes in preparation for protein synthesis.	Leucine-Specific tRNA,Transfer RNA, Leu,tRNALeu,tRNA(Leu),Leu Transfer RNA,Leucine Specific tRNA,RNA, Leu Transfer,tRNA, Leucine-Specific