Cloning of a human tRNA isopentenyl transferase

Identification and functional characterization of the candidate tumor suppressor gene TRIT1 in human lung cancer

“…Previous analysis of conserved motifs in the reported human TRIT1 transcript identified an ATP/GTP motif A in the amino-terminal portion of the protein (residues 30-37) (Golovko et al, 2000). Although neither ATP nor GTP is a direct substrate of tRNA-IPT enzymes, an inhibitory effect of several di-and tri-nucleotides has been described in both E. coli (Leung et al, 1997) and A. thaliana (Sakakibara and Takei, 2002), thus pointing to a possible regulatory role of this domain for the enzymatic activity in vivo.…”

“…To explain unsuccessful attempts to amplify the TRIT1 gene from human lung cDNAs using primers including the start and stop codon of clone AF074918 isolated from embryo (Golovko et al, 2000), we screened a human lung cDNA library for possible differences in the sequence of the TRIT1 gene. PCR screening revealed nine positive clones, six of which were confirmed by direct sequencing to contain the TRIT1 gene.…”

“…Addition of i 6 A on residue 37 of tRNA molecules is catalysed by tRNA-IPTs using W2-dimethylallyl pyrophosphate as donor of the isopentenyl group. tRNA-IPT genes have been identified and cloned in several organisms, including miaA from Escherichia coli (Caillet and Droogmans, 1988), MOD5 from Saccharomyces cerevisiae (Dihanich et al, 1987), TRIT1 from Homo sapiens (Golovko et al, 2000), gro-1 from Caenorhabditis elegans (Lemieux et al, 2001), and AtIPT2 from Arabidopsis thaliana (Takei et al, 2001). Mutations in tRNA-IPT genes significantly influence several biological functions: mutations in the miaA gene affect bacterial growth rate (Diaz et al, 1987) and the rate of GC to TA spontaneous transversions (Connolly and Winkler, 1989); yeast strains with defective MOD5 activity suppress nonsense mutations less efficiently; and gro-1 mutants of C. elegans show a slower developmental rate and an increased lifespan.…”

Cytokinins - recent news and views of evolutionally old molecules

“…Certain tRNAs that bind to codons starting with an uracil contain, at position 37, an adenine residue modified by an isopentenyl moiety (Golovko et al 2000). Such prenylation of tRNA belongs to nucleotide hypermodifications that are important for the efficiency and fidelity of protein translation by the ribosome (reviewed by Persson et al 1994).…”

“…CKs and their functions are not unique to plants. CKs are involved in RNA translation in phyllogeneticaly distinct organisms from bacteria to humans (Persson et al 1994;Golovko et al 2000), and various plant-interacting organisms employ or manipulate CKs to sequester plant developmental programmes to their own ends (Schultz 2002).…”