The wheat chloroplast gene for CF sub(0) subunit I of ATP synthase contains a large intron

The gene for CF sub(0) subunit I of ATP synthase has been located in wheat chloroplast DNA, between the genes for CF sub(0) subunit III and alpha subunit of CF sub(1). Nucleotide sequencing and analysis of RNA-DNA hybrids indicated that the gene is interrupted by an 823-bp intron which has boundaries similar to those previously described for the introns in protein-coding chloroplast genes of Euglena gracilis). The deduced amino acid sequence of CF sub(0) subunit I indicates a polypeptide of 183 amino acid residues. However, N-terminal amino acid sequencing of the mature spinach CF sub(0) subunit I suggests that the protein is synthesised with a N-terminal extension of 17 amino acid residues and is processed to give a protein of mol. wt. 19,001 of 166 amino acids residues. The mature CF sub(0) subunit I shows similarities in primary and predicted secondary structure to F sub(0) subunit b of Escherichia coli) ATP synthase. A major transcript of 3.3 kb containing sequences from the genes for CF sub(0) subunit III, subunit I and CF sub(1) subunit alpha has been observed by RNA-DNA hybridisation.