Plant nuclear tRNAMet genes are ubiquitously interrupted by introns |
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Authors: | Kazuhito Akama Mika Kashihara |
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Institution: | (1) Department of Biology, Faculty of Science, Shimane University, 690 Matsue, Japan;(2) Present address: Graduate Department of Gene Sciences, Faculty of Sciences, Hiroshima University, 732 Higashi-Hiroshima, Japan |
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Abstract: | We have isolated three independent clones for nuclear elongator tRNAMet genes from an Arabidopsis DNA library using a tRNAMet-specific probe generated by PCR. Each of the coding sequences for tRNAMet in these clones is identical and is interrupted by an identical 11 bp long intervening sequence at the same position in the anticodon loop of the tRNA. Their sequences differ at two positions from the intron in a soybean counterpart. Southern analysis of Arabidopsis DNA demonstrates that a gene family coding for tRNAMet is dispersed at at least eight loci in the genome. The unspliced precursor tRNAMet intermediate was detected by RNA analysis using an oligonucleotide probe complementary to the putative intron sequence. In order to know whether introns commonly interrupt plant tRNAMet genes, their coding sequences were PCR-amplified from the DNAs of eight phylogenetically separate plant species. All 53 sequences determined contain 10 to 13 bp long intervening sequences, always positioned one base downstream from the anticodon. They can all be potentially folded into the secondary structure characteristic for plant intron-containing precursor tRNAs. Surprisingly, GC residues are always present at the 5-distal end of each intron. |
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Keywords: | Arabidopsis thaliana intron plant tRNAMet genes precursor tRNA splicing |
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