Hybridization of bean chloroplast transfer RNAs to chloroplast DNA.

Bean (Phaseolus vulgaris) chloroplast tRNAsLeu and tRNAsPhe hybridize to chloroplast DNA, whereas the corresponding cytoplasmic tRNA species do not, suggesting that chloroplast transfer RNAs are coded for by chloroplast DNA. The hybridization of the three chloroplast tRNAsLeu or of the two tRNAsPhe isoacceptors is not additive, and the isoacceptors compete with each other in the hybridization to chloroplast DNA, suggesting that these isoacceptors are coded for by the same gene(s) and differ only in the extent of post-transcriptional modification. Although hererologous aminoacylation reactions and comparisons of base composition suggest a resemblance between chloroplast and procaryotic tRNAs, only a slight cross hybridization reaction was observed between chloroplast and Escherichia coli leucyl- or phenylalanyl-tRNAs and DNAs.