title: Euglena gracilis chloroplast transfer RNA transcription units. II. Nucleotide sequence analysis of a tRNAVal-tRNAAsn-tRNAArg-tRNALeu gene cluster.
abstract: The tRNA-coding locus of the 8.2-kilobase pair (kbp) Eco RI fragments Eco G of Euglena gracilis Klebs, strain Z Pringsheim chloroplast DNA was chosen for detailed analysis. Two recombinant plasmids, pPG14, containing Eco G and the vector pMB9, and pEZC23, containing the chloroplast DNA fragment HindIII B cloned in pBR322 were employed for the study. The tRNA locus was mapped to an 0.8-kbp region of Eco G also present in HindIII B. The DNA sequence of a 1.6 kbp from HindIII B, containing the entire tRNA gene locus was determined. Four tRNA genes were identified from the DNA sequence. The gene organization is tRNAVal-16 bp spacer-tRNAAsn-3 bp spacer-tRNAArg-45 bp spacer-tRNALeu. The tRNALeu gene is of the opposite polarity as the other three genes. This is the first evidence of such a tRNA cluster for a chloroplast genome. Also evident from the DNA sequence, 132 bp from the 5'-end of the tRNALeu gene, is a putative gene or pseudogene for a chloroplast protein.
mesh_terms: D001482:Base Composition; D001483:Base Sequence; D002736:Chloroplasts / Q000378:metabolism*; D004262:DNA Restriction Enzymes; D005056:Euglena gracilis / Q000235:genetics*; D005796:Genes; D009690:Nucleic Acid Conformation; D009693:Nucleic Acid Hybridization; D012343:RNA, Transfer / Q000235:genetics*; D012346:RNA, Transfer, Amino Acyl / Q000235:genetics; D014158:Transcription, Genetic
chemical_list: D012346:RNA, Transfer, Amino Acyl; D012343:RNA, Transfer; D004262:DNA Restriction Enzymes