Genes for tRNAIle and tRNAAla in the spacer between the 16S and 23S rRNA genes of a blue-green alga: strong homology to chloroplast tRNA genes and tRNA genes of the E. coli rrnD gene cluster.

A 6.3 kbp Eco RI-Bam HI fragment which carries most of one of the two rRNA gene clusters of the blue-green alga Anacystis nidulans was cloned into plasmid pBR322. Sequence analysis of the spacer region between the 16S and 23S rRNA genes reveals the presence of genes for tRNAIle and tRNAAla. The 16S rRNA gene is separated from the tRNAIle gene by a 162 bp spacer which shows significant homology to the comparable region in Zea mays plastids. The spacer between the two tRNA genes is 33 bp long and can be folded into a 9 bp stem and loop structure. The 5' portion of the tRNAIle gene is 60% homologous to a "pseudogene"-like sequence which maps beyond the 5S rRNA gene.