The gene for a spinach chloroplast isoleucine tRNA has a methionine anticodon

The nucleotide sequence of the gene for spinach chloroplast tRNAIle1 has been determined. The gene is found in two copies located in the inverted repeat regions of spinach chloroplast DNA, but not within the ribosomal RNA spacer. Both copies of the tRNAIle1 gene have been sequenced and found to be identical. A very unusual characteristic of the tRNAIle1 gene is that the anticodon is CAT which is a methionine anticodon. In the tRNA the C residue in the anticodon is subsequently modified, presumably to prevent misreading of the genetic code. The spinach chloroplast tRNAIle1 gene is colinear with its RNA sequence and does not contain an intervening sequence as has been reported for maize chloroplast tRNAIle2 (Koch, W., Edwards, K., and Kossel, H. (1981) Cell 25, 203-213). The tRNAIle1 gene does not code for the 3'-terminal CCA end, nor do any other tRNA genes appear to be contiguous with this gene.