SUMMARY PARAGRAPH for TPT1
TPT1 is an essential gene that encodes tRNA 2'-phosphotransferase, which catalyzes the final step of tRNA splicing (1). In tRNA processing, an intron is removed from the tRNA transcript by the multisubunit tRNA splicing endonuclease (comprising Sen2p, Sen15p, Sen34p, and Sen54p); the resulting half-molecules are joined by the tRNA ligase Trl1p (reviewed in reference 3). Tpt1p catalyzes the transfer of the splice junction 2'-phosphate from ligated tRNA to NAD to produce ADP-ribose 1"-2" cyclic phosphate (1). In a conditional lethal tpt1 mutant, 2'-phosphorylated tRNAs accumulate, and the tRNAs show altered posttranscriptional modification (4). Enzymes similar to Tpt1p are found in other eukaryotes; a predicted protein from S. pombe shows considerable sequence similarity to Tpt1p (1, 5). E. coli also contains a Tpt1p homolog, although it does not have the class of tRNA splicing found in eukaryotes (5).
Last updated: 2000-04-18