Structure and cotranscription of tobacco chloroplast genes for tRNA^Glu(UUC), tRNA^Tyr(GUA) and tRNA^Asp(GUC)

Abstract

The location and nucleotide sequences of tobacco chloroplast genes for tRNAGlu(UUC), tRNATyr(GUA) and tRNAAsp(GUC) have been determined. These genes lie midway between the genes for alpha and beta/epsilon subunits of H+-ATPase on the large single-copy region of the chloroplast DNA. The gene organization is tRNAGlu - 59bp spacer - tRNATyr - 108bp spacer - tRNAAsp on the same DNA strand. Northern blot hybridization studies revealed that these three tRNA genes are cotranscribed. The transcription initiation site was localized at 24 bp upstream from the tRNAGlu coding region and its termination site at 90 bp downstream from the tRNAAsp coding region by S1 mapping. The tricistronic tRNA precursor is thus calculated to be 512 bases long. Its processing was also studied by S1 mapping.