EUGLENA-GRACILIS CHLOROPLAST TRANSFER-RNA TRANSCRIPTION UNITS - NUCLEOTIDE-SEQUENCE ANALYSIS OF A TRANSFER RNA-THR TRANSFER-RNA-GLY TRANSFER-RNA-MET TRANSFER-RNA-SER TRANSFER-RNA-GLN GENE-CLUSTER

  • 1 January 1983
    • journal article
    • research article
    • Vol. 258  (9) , 5512-5518
Abstract
The arrangement and the nucleotide sequence of the tRNA genes in the 2.0-kilobase-pair EcoRI restriction fragment EcoQ of E. gracilis Klebs, strain Z Pringsheim chloroplast DNA were determined. This fragment, cloned in pBR325 to form the plasmid pEZC300, contains 5 tRNA genes. The DNA insert of this plasmid, a known tRNA gene locus was mapped by Southern gel analysis using a 32P-labeled oligodeoxynucleotide tRNA gene probe. The DNA sequence of 870 base pairs (bp) from EcoQ containing the entire tRNA gene locus was determined. The organization of this tRNA gene cluster on the E. gracilis chloroplast chromosome is .**GRAPHIC**. .**GRAPHIC**. .**GRAPHIC**. .**GRAPHIC**. .**GRAPHIC**. The .**GRAPHIC**. and .**GRAPHIC**. gene sequences are of the opposite polarity as the other 3 gene sequences, but of the same polarity as the rRNA genes. The tRNAMet gene is a putative initiator tRNA. The 5 tRNA genes are separated and flanked by A-T-rich spacer sequences. This gene arrangement is consistent with the model that E. gracilis chloroplast tRNA genes are transcribed into multicistronic tRNA precursors. The DNA sequences have been used to deduce the primary and secondary structures of the tRNAs.