Organization and nucleotide sequence of the genes for spinach chloroplast tRNAGlu and tRNATyr

Abstract

The map location and nucleotide sequence of the genes and flanking regions for tRNA_UUC ^Glu (trnE) and tRNA_GUA ^Tyr (trnY) from spinach (Spinacia oleracea) chloroplast DNA have been determined. The genes lie approximately midway between the genes for tRNA_GGU ^Thr (trnT) and tRNA_GUC ^Asp (trnD) on BamH1 fragment 8b, the arrangement being trnT, 458 bp, trnE, 64 bp, trnY, 409 bp, trnD. trnE and trnY are encoded by the same DNA strand as trnD and the direction of their transcription is divergent with respect to the transcription of trnT. trnE and trnY are 89% and 74% homologous, respectively, with the corresponding Euglena gracilis chloroplast genes. The corresponding homologies between the spinach chloroplast and E. coli genes are 72% and 61%. trnE is unusual in that it has the sequence 5'ATTCNA rather than 5'GTTCNA in the TΨ arm. Northern hybridizations to chloroplast RNA with restriction fragments carrying trnE and trnY sequences indicated that both genes are transcribed in vivo.