title: Euglena gracilis chloroplast ribosomal RNA transcription units. II. Nucleotide sequence homology between the 16 S--23 S ribosomal RNA spacer and the 16 S ribosomal RNA leader regions.
abstract: The DNA sequences of two segments of the ribosomal RNA transcription units of Euglena gracilis Pringsheim strain Z chloroplast DNA have been determined. The first is from the 16 S to 23 S rRNA spacer region. The nucleotide sequence determined includes 64 bp from the 3'-end of the 16 S rRNA gene, the adjacent 87-bp spacer containing 68A-T base pairs, a tRNAIle gene, a 9-bp spacer, a tRNAAla gene, a spacer of approximately 15 bp, and the first 120 bp from the 5'-end of the 23 S rRNA gene. The gene organization of the 16 S to 23 S rRNA spacer, the identity of the tRNA genes, and the tRNA anticodons for the E. gracilis rRNA transcription units are identical with that of the rrnA, D, and X operons of Escherichia coli. The second DNA segment which was sequenced is from a region preceding the 5'-end of the 16 S rRNA gene. Within a continuous region of 189 bp in this 16 S rRNA leader sequence, 68% of the bases are homologous to the 16 S rRNA to 23 S rRNA spacer region. This homology includes the 3'-end of the 16 S rRNA gene, the adjacent spacer, and a complete "pseudo" tRNAIle gene. This leader sequence which has the same polarity as the rRNA transcripts, is flanked by nucleotide sequences resembling partial tRNA genes.
mesh_terms: D001483:Base Sequence; D002736:Chloroplasts / Q000378:metabolism*; D004247:DNA / Q000378:metabolism; D004262:DNA Restriction Enzymes; D005056:Euglena gracilis / Q000378:metabolism*; D008970:Molecular Weight; D009690:Nucleic Acid Conformation; D012335:RNA, Ribosomal / Q000096:biosynthesis*; D012343:RNA, Transfer / Q000096:biosynthesis*; D014158:Transcription, Genetic
chemical_list: D012335:RNA, Ribosomal; D004247:DNA; D012343:RNA, Transfer; D004262:DNA Restriction Enzymes