Location, nucleotide sequence and expression of the proton-translocating subunit gene of theE. gracilis chloroplast ATP synthase.

A 1700 base pairHindIII restriction fragment from theE. gracilis chloroplast chromosome has been shown to contain the gene for the proton-translocating subunit of the ATP synthase (atpH). The gene was mapped by heterologous hybridization using internal sequences of the gene from wheat and spinach chloroplast DNA. Each chloroplast chromosome contains a single copy of atpH, which is located close to the gene for the alpha subunit of the ATP synthase (atpA). The nucleotide sequence of the gene is uninterrupted by introns. The predicted sequence of 77 amino acids is 70% homologous to that of the wheat and spinach polypeptides. The gene is expressedin vivo as shown by hybridization of atpH probes to cellulose nitrate filter blots of total chloroplast RNA. 5'-proximal to the atpH locus on the clonedHindIII fragment are 38 codons from the carboxy terminus of an open reading frame which may be another ATP synthase subunit. Transcription of the ORF and the atpH gene may be as part of a large polycistronic mRNA.