The gamma-subunit of spinach chloroplast ATP synthase: isolation and characterisation of cDNA and genomic clones

Abstract

cDNA and genomic clones encoding the complete precursor polypeptide of the gamma-subunit of spinach chloroplast ATP synthase have been isolated and characterised. The longest cDNA (1320 bp), selected from a lambda gt11 spinach cDNA library, encoded a 364 amino acid residue protein (Mr 40,028) that included a putative 41 residue N-terminal transit peptide. All the gamma-subunit cDNAs analysed were derived from the same gene and Southern blot analysis of Bam HI restricted spinach DNA showed only one hybridising band (ca. 15 kb). Analysis of the cloned 15 kb genomic fragment, selected from a lambda EMBL4 spinach DNA library with a cDNA probe, confirmed there was a single gene for the gamma-subunit. Sequencing, primer extension and northern blot analysis showed the gene contains two introns, 1066 and 665 bp in length, a 173 bp 5' untranslated region and a 213 bp 3' untranslated region. A 1450 nucleotide gamma-subunit transcript was detected in RNA from light-grown and dark-grown spinach.